ardupilot/Tools/ArduPPM/Libraries/PPM_Encoder_v3.h

1475 lines
48 KiB
C

// -------------------------------------------------------------
// PPM ENCODER V3.0.0 (12-10-2012)
// -------------------------------------------------------------
// By: John Arne Birkeland - 2012
// By Olivier ADLER : PPM redundancy mode - APM v1.x adaptation and "difficult" receiver testing - 2012
//
// -------------------------------------------------------------
// See changelog_v3 for a complete descrition of changes
// -------------------------------------------------------------
//
// 12-10-2012
// V3.0.0 - Added dual input PPM redundancy mode with auto switchover. This is mainly for dual PPM receivers setup.
//
// -------------------------------------------------------------
// Not for production - Work in progress
#pragma once
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/wdt.h>
#include <util/delay.h>
#ifndef F_CPU
#define F_CPU 16000000UL
#endif
#ifndef true
#define true 1
#endif
#ifndef false
#define false 0
#endif
#ifndef bool
#define bool _Bool
#endif
// -------------------------------------------------------------
// GLOBAL SETTINGS
// -------------------------------------------------------------
// Number of Timer1 ticks for 1 microsecond
#define TICKS_FOR_ONE_US F_CPU / 8 / 1000 / 1000
// -------------------------------------------------------------
// INPUT MODE (by jumper selection)
// -------------------------------------------------------------
#define JUMPER_SELECT_MODE 0 // Default - PPM passtrough mode selected if input pins 2&3 shorted. Normal servo input (pwm) if not shorted.
#define SERVO_PWM_MODE 1 // Normal 8 channel servo (pwm) input
#define PPM_PASSTROUGH_MODE 2 // PPM signal passtrough on channel 1 if input pins 2&3 shorted
#define PPM_REDUNDANCY_MODE 3 // PPM redundancy on channels 1 and 2 if input pins 3&4 shorted
#define SPEKTRUM_MODE 4 // Spektrum satelitte on channel 1 (reserved - not yet implemented)
volatile uint8_t servo_input_mode = JUMPER_SELECT_MODE;
// -------------------------------------------------------------
// PPM REDUNDANCY MODE SETTINGS
// -------------------------------------------------------------
#define SWITCHOVER_CHANNEL_A 9 // Receiver 1 PPM channel to force receiver 2. Use 0 for no switchover channel
// Must be choosed between 6 to 16. Preferabily from 9 to 16 so that APM can use
// channels 1 to 8.
#define SWITCHOVER_1_to_2_DELAY_MS 50 // Delay for switching to receiver 2
#define SWITCHOVER_2_to_1_DELAY_MS 200 // Delay for switching back to receiver 1
#define CHANNEL_COUNT_DETECTION_THRESHOLD 10 // Valid frames detected before channel count validation
// PPM input frame mode receiver 1
// -------------------------------------------------------------
#define PPM_CH1_STANDARD // Standard PPM : 1520 us +/- 600 us - 8 channels - 20 ms frame period
//#define PPM_CH1_STANDARD_EXTENDED // 9 channels : 1520 us +/- 600 us - 9 channels - 22.1 ms slower frame period
//#define PPM_CH1_V2 // PPMv2 : 760 us +/- 300 us - 16 Channels - normal 20 ms frame period
//#define PPM_CH1_V3 // PPMv3 16 channels with long sync symbol : 1050 us +/- 300 us - 25 ms frame period
// PPM input frame mode receiver 2
// -------------------------------------------------------------
#define PPM_CH2_STANDARD
//#define PPM_CH2_STANDARD_EXTENDED
//#define PPM_CH2_V2
//#define PPM_CH2_V3
// PPM1 input : frame formats definitions
// -------------------------------------------------------------
#if defined (PPM_CH1_STANDARD) || defined (PPM_CH1_STANDARD_EXTENDED)
#ifdef PPM_CH1_STANDARD_EXTENDED
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 9
// Frame period
#define PPM_CH1_FRAME_PERIOD 22500 // frame period (microseconds)
#else
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 8
// Frame period
#define PPM_CH1_FRAME_PERIOD 20000 // frame period (microseconds)
#endif
// PPM channels limits
#define PPM_CH1_VAL_MIN TICKS_FOR_ONE_US * 920
#define PPM_CH1_VAL_MAX TICKS_FOR_ONE_US * 2120
#define PPM_CH1_VAL_CENTER TICKS_FOR_ONE_US * 1520
#define PPM_CH1_FORCE_VAL_MIN 1800
// PPM channel pre pulse lenght
#define PPM_CH1_CHANNEL_PREPULSE_LENGHT 400
// PPM frame sync symbol limits
#define PPM_CH1_MIN_SYNC_LENGHT PPM_CH1_FRAME_PERIOD - ( PPM_CH1_MAX_CHANNELS * PPM_CH1_VAL_MAX ) - PPM_CH1_CHANNEL_PREPULSE_LENGHT // Sync symbol detection
#define PPM_CH1_MAX_SYNC_LENGHT PPM_CH1_FRAME_PERIOD - ( PPM_CH1_MIN_CHANNELS * PPM_CH1_VAL_MIN ) - PPM_CH1_CHANNEL_PREPULSE_LENGHT // Sync timeout
#endif
#ifdef PPM_CH1_V2 (PPMv2 is a 50 Hz 16 channels mode)
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 16
// Frame period
#define PPM_CH1_FRAME_PERIOD 20000 // frame period (microseconds)
// PPM channels limits
#define PPM_CH1_VAL_MIN TICKS_FOR_ONE_US * 460
#define PPM_CH1_VAL_MAX TICKS_FOR_ONE_US * 1060
#define PPM_CH1_VAL_CENTER TICKS_FOR_ONE_US * 760
#define PPM_CH1_FORCE_VAL_MIN 900
// PPM channel pre pulse lenght
#define PPM_CH1_CHANNEL_PREPULSE_LENGHT 200
// PPM frame sync symbol limits
#define PPM_CH1_MIN_SYNC_LENGHT PPM_CH1_FRAME_PERIOD - ( PPM_CH1_MAX_CHANNELS * PPM_CH1_VAL_MAX ) - PPM_CH1_CHANNEL_PREPULSE_LENGHT // Sync symbol detection
#define PPM_CH1_MAX_SYNC_LENGHT PPM_CH1_FRAME_PERIOD - ( PPM_CH1_MIN_CHANNELS * PPM_CH1_VAL_MIN ) - PPM_CH1_CHANNEL_PREPULSE_LENGHT // Sync timeout
#endif
#ifdef PPM_CH1_V3 (PPMv3 is a 40 Hz slower refresh rate 16 channels mode)
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 16
// Frame period
#define PPM_CH1_FRAME_PERIOD 25000 // frame period (microseconds)
// PPM channels limits
#define PPM_CH1_VAL_MIN TICKS_FOR_ONE_US * 750
#define PPM_CH1_VAL_MAX TICKS_FOR_ONE_US * 1350
#define PPM_CH1_VAL_CENTER TICKS_FOR_ONE_US * 1050
#define PPM_CH1_FORCE_VAL_MIN 1260
// PPM channel pre pulse lenght
#define PPM_CH1_CHANNEL_PREPULSE_LENGHT 400
// PPM frame sync symbol limits
#define PPM_CH1_MIN_SYNC_LENGHT PPM_CH1_FRAME_PERIOD - ( PPM_CH1_MAX_CHANNELS * PPM_CH1_VAL_MAX ) - PPM_CH1_CHANNEL_PREPULSE_LENGHT // Sync symbol detection
#define PPM_CH1_MAX_SYNC_LENGHT PPM_CH1_FRAME_PERIOD - ( PPM_CH1_MIN_CHANNELS * PPM_CH1_VAL_MIN ) - PPM_CH1_CHANNEL_PREPULSE_LENGHT // Sync timeout
#endif
// PPM2 input : frame format definitions
// -------------------------------------------------------------
#if defined (PPM_CH2_STANDARD) || defined (PPM_CH2_STANDARD_EXTENDED)
#ifdef PPM_CH2_STANDARD_EXTENDED
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 9
// Frame period
#define PPM_CH2_FRAME_PERIOD 22500 // frame period (microseconds)
#else
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 8
// Frame period
#define PPM_CH2_FRAME_PERIOD 20000 // frame period (microseconds)
#endif
// PPM channels limits
#define PPM_CH2_VAL_MIN TICKS_FOR_ONE_US * 920
#define PPM_CH2_VAL_MAX TICKS_FOR_ONE_US * 2120
#define PPM_CH2_VAL_CENTER TICKS_FOR_ONE_US * 1520
// PPM channel pre pulse lenght
#define PPM_CH1_CHANNEL_PREPULSE_LENGHT 400
// PPM frame sync symbol limits
#define PPM_CH2_MIN_SYNC_LENGHT PPM_CH2_FRAME_PERIOD - ( PPM_CH2_MAX_CHANNELS * PPM_CH2_VAL_MAX ) - PPM_CH2_CHANNEL_PREPULSE_LENGHT // Sync symbol detection
#define PPM_CH2_MAX_SYNC_LENGHT PPM_CH2_FRAME_PERIOD - ( PPM_CH2_MIN_CHANNELS * PPM_CH2_VAL_MIN ) - PPM_CH2_CHANNEL_PREPULSE_LENGHT // Sync timeout
#endif
#ifdef PPM_CH2_V2 (PPMv2 is a 50 Hz 16 channels mode)
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 16
// Frame period
#define PPM_CH2_FRAME_PERIOD 20000 // frame period (microseconds)
// PPM channels limits
#define PPM_CH2_VAL_MIN TICKS_FOR_ONE_US * 460
#define PPM_CH2_VAL_MAX TICKS_FOR_ONE_US * 1060
#define PPM_CH2_VAL_CENTER TICKS_FOR_ONE_US * 760
// PPM channel pre pulse lenght
#define PPM_CH1_CHANNEL_PREPULSE_LENGHT 200
// PPM sync symbol limits
#define PPM_CH2_MIN_SYNC_LENGHT PPM_CH2_FRAME_PERIOD - ( PPM_CH2_MAX_CHANNELS * PPM_CH2_VAL_MAX ) - PPM_CH2_CHANNEL_PREPULSE_LENGHT // Sync symbol detection
#define PPM_CH2_MAX_SYNC_LENGHT PPM_CH2_FRAME_PERIOD - ( PPM_CH2_MIN_CHANNELS * PPM_CH2_VAL_MIN ) - PPM_CH2_CHANNEL_PREPULSE_LENGHT // Sync timeout
#endif
#ifdef PPM_CH2_V3 (PPMv3 is a 40 Hz slower refresh rate 16 channels mode)
// PPM channel count limits
#define PPM_CH1_MIN_CHANNELS 4
#define PPM_CH1_MAX_CHANNELS 16
// Frame period
#define PPM_CH2_FRAME_PERIOD 25000 // frame period (microseconds)
// PPM channels limits
#define PPM_CH2_VAL_MIN TICKS_FOR_ONE_US * 750
#define PPM_CH2_VAL_MAX TICKS_FOR_ONE_US * 1350
#define PPM_CH2_VAL_CENTER TICKS_FOR_ONE_US * 1050
// PPM channel pre pulse lenght
#define PPM_CH1_CHANNEL_PREPULSE_LENGHT 400
// PPM sync symbol limits
#define PPM_CH2_MIN_SYNC_LENGHT PPM_CH2_FRAME_PERIOD - ( PPM_CH2_MAX_CHANNELS * PPM_CH2_VAL_MAX ) - PPM_CH2_CHANNEL_PREPULSE_LENGHT // Sync symbol detection
#define PPM_CH2_MAX_SYNC_LENGHT PPM_CH2_FRAME_PERIOD - ( PPM_CH2_MIN_CHANNELS * PPM_CH2_VAL_MIN ) - PPM_CH2_CHANNEL_PREPULSE_LENGHT // Sync timeout
#endif
// -------------------------------------------------------------
// SERVO PWM MODE input settings
// -------------------------------------------------------------
// Number of input PWM channels
#define PWM_CHANNELS 8
// PWM channels minimum values
#define PWM_VAL_MIN TICKS_FOR_ONE_US * 920 - PPM_PRE_PULSE
// PWM channels maximum values
#define PWM_VAL_MAX TICKS_FOR_ONE_US * 2120 - PPM_PRE_PULSE
// PWM input filters
// Using both filters is not recommended and may reduce servo input resolution
// #define _AVERAGE_FILTER_ // Average filter to smooth servo input capture jitter
// #define _JITTER_FILTER_ // Cut filter to remove 0,5us servo input capture jitter
// -------------------------------------------------------------
// PPM output frame format
// -------------------------------------------------------------
// Number of output PPM channels
#define PPM_CHANNELS 8
// 400us PPM pre pulse
#define PPM_PRE_PULSE TICKS_FOR_ONE_US * 400
// PPM channels center positions
#define PPM_VAL_CENTER TICKS_FOR_ONE_US * 1520 - PPM_PRE_PULSE
// PPM period 18.5ms - 26.5ms (54hz - 37Hz)
#define PPM_PERIOD TICKS_FOR_ONE_US * ( 22500 - ( PPM_CHANNELS * 1520 ) )
// Size of ppm[..] data array
#define PPM_ARRAY_MAX PPM_CHANNELS * 2 + 2
// -------------------------------------------------------------
// PPM output default values
// -------------------------------------------------------------
// Throttle default at power on
#define PPM_THROTTLE_DEFAULT TICKS_FOR_ONE_US * 1100 - PPM_PRE_PULSE
// Throttle during failsafe
#define PPM_THROTTLE_FAILSAFE TICKS_FOR_ONE_US * 920 - PPM_PRE_PULSE
// CH5 power on values (mode selection channel)
#define PPM_CH5_MODE_4 TICKS_FOR_ONE_US * 1555 - PPM_PRE_PULSE
// -------------------------------------------------------------
// PPM output frame variables
// -------------------------------------------------------------
// Data array for storing output PPM (8 channels) pulse widths.
volatile uint16_t ppm[ PPM_ARRAY_MAX ] =
{
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 1
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 2
PPM_PRE_PULSE,
PPM_THROTTLE_DEFAULT, // Channel 3 (throttle)
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 4
PPM_PRE_PULSE,
PPM_CH5_MODE_4, // Channel 5 (flight mode)
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 6
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 7
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 8
PPM_PRE_PULSE,
PPM_PERIOD
};
// Output PPM FAILSAFE values
const uint16_t failsafe_ppm[ PPM_ARRAY_MAX ] =
{
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 1
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 2
PPM_PRE_PULSE,
PPM_THROTTLE_FAILSAFE, // Channel 3 (throttle)
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 4
PPM_PRE_PULSE,
PPM_CH5_MODE_4, // Channel 5
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 6
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 7
PPM_PRE_PULSE,
PPM_VAL_CENTER, // Channel 8
PPM_PRE_PULSE,
PPM_PERIOD
};
// -------------------------------------------------------------
// AVR parameters for PhoneDrone and APM2 boards using ATmega32u2
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
#define SERVO_DDR DDRB
#define SERVO_PORT PORTB
#define SERVO_INPUT PINB
#define SERVO_INT_VECTOR PCINT0_vect
#define SERVO_INT_MASK PCMSK0
#define SERVO_INT_CLEAR_FLAG PCIF0
#define SERVO_INT_ENABLE PCIE0
#define SERVO_TIMER_CNT TCNT1
#define PPM_DDR DDRC
#define PPM_PORT PORTC
#define PPM_OUTPUT_PIN PC6
#define PPM_INT_VECTOR TIMER1_COMPA_vect
#define PPM_COMPARE OCR1A
#define PPM_COMPARE_FLAG COM1A0
#define PPM_COMPARE_ENABLE OCIE1A
#define USB_DDR DDRC
#define USB_PORT PORTC
#define USB_PIN PC2
// true if we have received a USB device connect event
static bool usb_connected;
// USB connected event
void EVENT_USB_Device_Connect(void)
{
// Toggle USB pin high if USB is connected
USB_PORT |= (1 << USB_PIN);
usb_connected = true;
// this unsets the pin connected to PA1 on the 2560
// when the bit is clear, USB is connected
PORTD &= ~1;
}
// USB disconnect event
void EVENT_USB_Device_Disconnect(void)
{
// toggle USB pin low if USB is disconnected
USB_PORT &= ~(1 << USB_PIN);
usb_connected = false;
// this sets the pin connected to PA1 on the 2560
// when the bit is clear, USB is connected
PORTD |= 1;
}
// AVR parameters for ArduPilot MEGA v1.4 PPM Encoder (ATmega328P)
#elif defined (__AVR_ATmega328P__) || defined (__AVR_ATmega328__)
#define SERVO_DDR DDRD
#define SERVO_PORT PORTD
#define SERVO_INPUT PIND
#define SERVO_INT_VECTOR PCINT2_vect
#define SERVO_INT_MASK PCMSK2
#define SERVO_INT_CLEAR_FLAG PCIF2
#define SERVO_INT_ENABLE PCIE2
#define SERVO_TIMER_CNT TCNT1
#define PPM_DDR DDRB
#define PPM_PORT PORTB
#define PPM_OUTPUT_PIN PB2
#define PPM_INT_VECTOR TIMER1_COMPB_vect
#define PPM_COMPARE OCR1B
#define PPM_COMPARE_FLAG COM1B0
#define PPM_COMPARE_ENABLE OCIE1B
#else
#error NO SUPPORTED DEVICE FOUND! (ATmega16u2 / ATmega32u2 / ATmega328p)
#endif
// Invalid SERVO input signals count
volatile uint8_t servo_input_errors = 0;
// Missing SERVO input signals flag
volatile bool servo_input_missing = true;
// PPM generator active flag
volatile bool ppm_generator_active = false;
// Brownout restart flag
volatile bool brownout_reset = false;
// ------------------------------------------------------------------------------
// PPM GENERATOR START - TOGGLE ON COMPARE INTERRUPT ENABLE
// ------------------------------------------------------------------------------
void ppm_start( void )
{
// Prevent reenabling an already active PPM generator
if( ppm_generator_active ) return;
// Store interrupt status and register flags
uint8_t SREG_tmp = SREG;
// Stop interrupts
cli();
// Make sure initial output state is low
PPM_PORT &= ~(1 << PPM_OUTPUT_PIN);
// Wait for output pin to settle
//_delay_us( 1 );
// Set initial compare toggle to maximum (32ms) to give other parts of the system time to start
SERVO_TIMER_CNT = 0;
PPM_COMPARE = 0xFFFF;
// Set toggle on compare output
TCCR1A = (1 << PPM_COMPARE_FLAG);
// Set TIMER1 8x prescaler
TCCR1B = ( 1 << CS11 );
// Enable output compare interrupt
TIMSK1 |= (1 << PPM_COMPARE_ENABLE);
// Indicate that PPM generator is active
ppm_generator_active = true;
// Restore interrupt status and register flags
SREG = SREG_tmp;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Turn on TX led if PPM generator is active
PORTD &= ~( 1<< PD5 );
#endif
}
// ------------------------------------------------------------------------------
// PPM GENERATOR STOP - TOGGLE ON COMPARE INTERRUPT DISABLE
// ------------------------------------------------------------------------------
void ppm_stop( void )
{
// Store interrupt status and register flags
uint8_t SREG_tmp = SREG;
// Stop interrupts
cli();
// Disable output compare interrupt
TIMSK1 &= ~(1 << PPM_COMPARE_ENABLE);
// Reset TIMER1 registers
TCCR1A = 0;
TCCR1B = 0;
// Indicate that PPM generator is not active
ppm_generator_active = false;
// Restore interrupt status and register flags
SREG = SREG_tmp;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Turn off TX led if PPM generator is off
PORTD |= ( 1<< PD5 );
#endif
}
// ------------------------------------------------------------------------------
// Watchdog Interrupt (interrupt only mode, no reboot)
// ------------------------------------------------------------------------------
ISR( WDT_vect ) // If watchdog is triggered then enable missing signal flag and copy failsafe values
{
// Use failsafe values if PPM generator is active or if chip has been reset from a brown-out
if ( ppm_generator_active || brownout_reset )
{
// Copy failsafe values to ppm[..]
for ( uint8_t i = 0; i < PPM_ARRAY_MAX; i++ )
{
ppm[ i ] = failsafe_ppm[ i ];
}
}
// If we are in PPM passtrough mode and a input signal has been detected, or if chip has been reset from a brown_out then start the PPM generator.
if( ( servo_input_mode == PPM_PASSTROUGH_MODE && servo_input_missing == false ) || brownout_reset )
{
// Start PPM generator
ppm_start();
brownout_reset = false;
}
// Set missing receiver signal flag
servo_input_missing = true;
// Reset servo input error flag
servo_input_errors = 0;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Turn on RX led if failsafe has triggered after ppm generator i active
if( ppm_generator_active ) PORTD &= ~( 1<< PD4 );
#endif
}
// ------------------------------------------------------------------------------
// ------------------------------------------------------------------------------
// SERVO/PPM INPUT - PIN CHANGE INTERRUPT
// ------------------------------------------------------------------------------
ISR( SERVO_INT_VECTOR )
{
// To store current servo input pins
uint8_t servo_pins;
// Servo input pin storage
static uint8_t servo_pins_old = 0;
// PWM Mode pulse start time
static uint16_t servo_start[ servo_channel ] = { 0, 0, 0, 0, 0, 0, 0, 0 };
// Missing throttle signal failsafe
static uint8_t throttle_timeout = 0;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Toggle LED delay
static uint8_t led_delay = 0;
#endif
// Read current servo timer
uint16_t servo_time = SERVO_TIMER_CNT;
// ------------------------------------------------------------------------------
// PPM redundancy mode
// ------------------------------------------------------------------------------
//---------------------------------------------------------------------
// Todo : Refine sync symbol limits after channel count detection
// Todo : Conversion to PPM output format (would be better if the main APM could follow format changes)
// Todo : sync between PPM input and output after switchover
// Todo : rework code from line 950 to end of redundancy mode
// Todo : Add optional delay inside switchover algo
// Todo : Add LED code for APM 1.4
//-------------------------------------------------------------------------
if( servo_input_mode == PPM_REDUNDANCY_MODE )
{
// -------------------------------------
// PPM redundancy mode - variables Init
// -------------------------------------
// PPM1 prepulse start
static uint16_t ppm1_prepulse_start;
// PPM2 prepulse start
static uint16_t ppm2_prepulse_start;
// PPM1 prepulse width
static uint16_t ppm1_prepulse_width;
// PPM2 prepulse width
static uint16_t ppm2_prepulse_width;
// PPM1 pulse start time
static uint16_t ppm1_start[ 16 ] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// PPM2 pulse start time
static uint16_t ppm2_start[ 16 ] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// PPM1 pulse lenght
static uint16_t ppm1_width[ 16 ] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// PPM2 pulse lenght
static uint16_t ppm2_width[ 16 ] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
// Reset PPM channels ( 0 = Sync Symbol )
static uint8_t ppm1_channel = 0; // Channel 0 = sync symbol
static uint8_t ppm2_channel = 0; // Channel 0 = sync symbol
// Frame sync flag
static bool sync_ch1 = false;
static bool sync_ch2 = false;
// Channel error flags
static bool channel_error_ch1 = true;
static bool channel_error_ch2 = true;
// Sync error flags
static bool sync_error_ch1 = true;
static bool sync_error_ch2 = true;
//---------------------------------------------------------
// ch2 switchover flag
static bool switchover_ch2 = false;
//---------------------------------------------------------
// Channel count detection ready flag
static bool channel_count_ready_ch1 = false;
static bool channel_count_ready_ch2 = false;
// Channel count detected flag
static bool channel_count_detected_ch1 = false;
static bool channel_count_detected_ch2 = false;
// Detected Channel count
static uint8_t channel_count_ch1 = PPM_CH1_MAX_CHANNELS;
static uint8_t channel_count_ch2 = PPM_CH2_MAX_CHANNELS;
// Detected Channel count previous value
static uint8_t previous_channel_count_ch1 = 0;
static uint8_t previous_channel_count_ch2 = 0;
// Channel count detection counter
static uint8_t channel_count_detection_counter_ch1 = 0;
static uint8_t channel_count_detection_counter_ch1 = 0;
// -----------------------------------
// PPM redundancy - decoder
// -----------------------------------
CHECK_START: // Start of PPM inputs check
// Store current PPM inputs pins
servo_pins = SERVO_INPUT;
// Calculate servo input pin change mask
uint8_t servo_change = servo_pins ^ servo_pins_old;
// -----------------------------------
// PPM redundancy - Ch1 decoding
// -----------------------------------
CHECK_LOOP: // Input PPM pins check loop
// Check if we have a pin change on PPM channel 1
if( servo_change & 1 )
{
// -----------------------------------------------------------------------------------------------------------------------
// Check if we've got a high level (raising edge, channel start or sync symbol end)
if( servo_pins & 1 )
{
// Check for pre pulse lenght
ppm1_prepulse_width = servo_time - ppm1_prepulse_start;
if ( true ) //Todo optionnal: We could add a test here for channel pre pulse lenght check
{
//We have a valid pre pulse
if( ppm1_channel == channel_count_ch1 ) // Check for last channel
{
// We are at latest PPM channel
sync_ch1 = false; // Reset sync flag
ppm1_channel = 0; // Reset PPM channel counter
}
else // We do not have yet reached the last channel
{
// Increment channel counter
ppm1_channel++;
}
}
else
{
//We do not have a valid pre pulse
sync_error_ch1 = true; // Set sync error flag
sync_ch1 = false; // Reset sync flag
ppm1_channel = 0; // Reset PPM channel counter
}
ppm1_start[ ppm1_channel ] = servo_time; // Store pulse start time for PPM1 input
}
// -----------------------------------------------------------------------------------------------------------------------
else // We've got a low level (falling edge, channel end or sync symbol start)
{
ppm1_width[ ppm1_channel ] = servo_time - ppm1_start[ ppm1_channel ]; // Calculate channel pulse lenght, or sync symbol lenght
if(sync_ch1 == true) // Are we synchronized ?
{
// Check channel pulse lenght validity
if( ppm1_width[ ppm1_channel ] > ( PPM_CH1_VAL_MAX - PPM_CH1_CHANNEL_PREPULSE_LENGHT ) ) || ( ppm1_width[ ppm1_channel ] < ( PPM_CH1_VAL_MIN - PPM_CH1_CHANNEL_PREPULSE_LENGHT ) ) // If we have a valid pulse lenght
{
// Reset channel error flag
channel_error_ch1 = false;
}
else // We do not have a valid channel lenght
{
if( ppm1_width[ ppm1_channel ] > PPM_CH1_MIN_SYNC_LENGHT ) || ( ppm1_width[ ppm1_channel ] < PPM_CH1_MAX_SYNC_LENGHT ) //Check for sync symbol
{
// We have a valid sync symbol
if( channel_count_detected_ch1 == false ) // Check if we do not have yet channel count detected
{
// We have detected channels count
channel_count_ch1 = ppm1_channel; // Store PPM1 channel count
channel_count_ready_ch1 = true; // Set PPM1 channel count detection ready flag
sync_error_ch1 = false; // Reset sync error flag
sync_ch1 = true; // Set sync flag
}
else // Channel count had been detected before
{
//We should not have a sync symbol here
sync_error_ch1 = true; // Set sync error flag
sync_ch1 = false; // Reset sync flag
}
ppm1_channel = 0; // Reset PPM channel counter
}
else // We do not have a valid sync symbol
{
channel_error_ch1 = true; // Set channel error flag
}
}
}
// ------------------------------------------------------------------------------
else // We are not yet synchronized
{
if( ppm1_width[ ppm1_channel ] > PPM_CH1_MIN_SYNC_LENGHT ) || ( ppm1_width[ ppm1_channel ] < PPM_CH1_MAX_SYNC_LENGHT ) //Check for sync symbol
{
// We have a valid sync symbol
sync_error_ch1 = false; // Reset sync error flag
sync_ch1 = true; // Set sync flag
}
else // We did not find a valid sync symbol
{
sync_error_ch1 = true; // Set sync error flag
sync_ch1 = false; // Reset sync flag
}
ppm1_channel = 0; // Reset PPM channel counter
}
}
ppm1_prepulse_start = servo_time; // Store prepulse start time
// -----------------------------------------------------------------------------------------------------------------------
}
// -----------------------------------
// PPM redundancy - Ch2 decoding
// -----------------------------------
// Check if we have a pin change on PPM channel 2
if( servo_change & 2 )
{
// -----------------------------------------------------------------------------------------------------------------------
// Check if we've got a high level (raising edge, channel start or sync symbol end)
if( servo_pins & 2 )
{
// Check for pre pulse lenght
ppm2_prepulse_width = servo_time - ppm2_prepulse_start;
if ( true ) //Todo optionnal: We could add a test here for channel pre pulse lenght check
{
//We have a valid pre pulse
if( ppm2_channel == channel_count_ch2 ) // Check for last channel
{
// We are at latest PPM channel
sync_ch2 = false; // Reset sync flag
ppm2_channel = 0; // Reset PPM channel counter
}
else // We do not have yet reached the last channel
{
// Increment channel counter
ppm2_channel++;
}
}
else
{
//We do not have a valid pre pulse
sync_error_ch2 = true; // Set sync error flag
sync_ch2 = false; // Reset sync flag
ppm2_channel = 0; // Reset PPM channel counter
}
ppm2_start[ ppm2_channel ] = servo_time; // Store pulse start time for PPM2 input
}
// -----------------------------------------------------------------------------------------------------------------------
else // We've got a low level (falling edge, channel end or sync symbol start)
{
ppm2_width[ ppm2_channel ] = servo_time - ppm2_start[ ppm2_channel ]; // Calculate channel pulse lenght, or sync symbol lenght
if(sync_ch2 == true) // Are we synchronized ?
{
// Check channel pulse lenght validity
if( ppm2_width[ ppm2_channel ] > ( PPM_CH2_VAL_MAX - PPM_CH2_CHANNEL_PREPULSE_LENGHT ) ) || ( ppm2_width[ ppm2_channel ] < ( PPM_CH2_VAL_MIN - PPM_CH2_CHANNEL_PREPULSE_LENGHT ) ) // If we have a valid pulse lenght
{
// Reset channel error flag
channel_error_ch2 = false;
}
else // We do not have a valid channel lenght
{
if( ppm2_width[ ppm2_channel ] > PPM_CH2_MIN_SYNC_LENGHT ) || ( ppm2_width[ ppm2_channel ] < PPM_CH2_MAX_SYNC_LENGHT ) //Check for sync symbol
{
// We have a valid sync symbol
if( channel_count_detected_ch2 == false ) // Check if we do not have yet channel count detected
{
// We have detected channels count
channel_count_ch2 = ppm2_channel; // Store PPM2 channel count
channel_count_ready_ch2 = true; // Set PPM2 channel count detection ready flag
sync_error_ch2 = false; // Reset sync error flag
sync_ch2 = true; // Set sync flag
}
else // Channel count had been detected before
{
//We should not have a sync symbol here
sync_error_ch2 = true; // Set sync error flag
sync_ch2 = false; // Reset sync flag
}
ppm2_channel = 0; // Reset PPM channel counter
}
else // We do not have a valid sync symbol
{
channel_error_ch2 = true; // Set channel error flag
}
}
}
// ------------------------------------------------------------------------------
else // We are not yet synchronized
{
if( ppm2_width[ ppm2_channel ] > PPM_CH2_MIN_SYNC_LENGHT ) || ( ppm2_width[ ppm2_channel ] < PPM_CH2_MAX_SYNC_LENGHT ) //Check for sync symbol
{
// We have a valid sync symbol
sync_error_ch2 = false; // Reset sync error flag
sync_ch2 = true; // Set sync flag
}
else // We did not find a valid sync symbol
{
sync_error_ch2 = true; // Set sync error flag
sync_ch2 = false; // Reset sync flag
}
ppm2_channel = 0; // Reset PPM channel counter
}
}
ppm2_prepulse_start = servo_time; // Store prepulse start time
// -----------------------------------------------------------------------------------------------------------------------
}
// -----------------------------------
// PPM redundancy - Post processing
// -----------------------------------
// Could be eventually run in the main loop for performances improvements if necessary
// sync mode between input and ouptput should clear performance problems
// -----------------
// Switchover code
// -----------------
// Check for PPM1 validity
if ( sync_error_ch1 == false ) && ( channel_error_ch1 == false) // PPM1 is valid
{
// check for PPM2 forcing (through PPM1 force channel)
if ( ppm1_width [ SWITCHOVER_CHANNEL ] > PPM_CH1_FORCE_VAL_MIN ) // Channel 2 forcing is alive
{
// Check for PPM2 validity
if ( sync_error_ch2 == false ) && ( channel_error_ch2 == false) // PPM2 is valid
{
// Check for PPM2 selected
if ( switchover_ch2 == true ) // PPM2 is selected
{
// Do nothing
}
else
{
// Switch to PPM2 without delay
if ( ppm2_channel == channel_count_ch2 ) // Check for last PPM2 channel before switching
{
switchover_ch2 == true; // Switch to PPM2
}
}
}
}
else // Check for PPM1 selected
{
if ( switchover_ch2 == false ) // PPM1 is selected
{
// Load PPM Output with PPM1
ppm[ ppm1_channel ] = ppm1_width;
}
else // PPM1 is not selected
{
// To Enhance : Optional switchover delay 2 to 1 here
if ( ppm1_channel == channel_count_ch1 ) // Check for last PPM1 channel before switching
{
switchover_ch2 == false; // Switch to PPM1
}
}
}
}
else // PPM1 is not valid
{
// Check for ppm2 validity
if ( sync_error_ch2 == false ) && ( channel_error_ch2 == false) // PPM2 is valid
{
// Check PPM2 selected
if ( switchover_ch2 == true ) // PPM2 is selected
{
// Load PPM Output with PPM2
ppm[ ppm2_channel ] = ppm2_width;
}
else // Switch to PPM2
{
// To Enhance : Optional switchover delay 1 to 2 here
if ( ppm2_channel == channel_count_ch2 ) // Check for last PPM2 channel before switching
{
switchover_ch2 == true; // Switch to PPM2
}
}
}
else // PPM2 is not valid
{
// load PPM output with failsafe values
}
}
// -----------------------------------
// Channel count post processing code
// -----------------------------------
// To enhance: possible global detection flag to avoid 2 channel_count_detected tests
// Ch1
if ( channel_count_detected_ch1 == true ) // Channel count for Ch1 was detected
{
// Do nothing
}
else // Do we have a channel count detection ready ?
{
if ( channel_count_ready_ch1 == true ) // If channel count is ready
{
// Check for detection counter
if ( channel_count_detection_counter_ch1 < CHANNEL_COUNT_DETECTION_THRESHOLD ) // Detection counter < Threshold
{
// Compare channel count with previous value
if ( channel_count_ch1 == previous_channel_count_ch1 ) // We have the same value
{
channel_count_detection_counter_ch1++; // Increment detection counter
}
else // We do not have the same value
{
channel_count_detection_counter_ch1 = 0; // Reset detection counter
}
previous_channel_count_ch1 = channel_count_ch1; // Load previous channel count with channel count
}
else // Detection counter >= Threshold
{
channel_count_detected_ch1 = true; // Channel count is now detected
}
channel_count_ready_ch1 = false; // Reset channel count detection ready flag
}
}
// Ch2
if ( channel_count_detected_ch2 == true ) // Channel count for ch2 was detected
{
// Do nothing
}
else // Do we have a channel count detection ready ?
{
if ( channel_count_ready_ch2 == true ) // If channel count is ready
{
// Check for detection counter
if ( channel_count_detection_counter_ch2 < CHANNEL_COUNT_DETECTION_THRESHOLD ) // Detection counter < Threshold
{
// Compare channel count with previous value
if ( channel_count_ch2 == previous_channel_count_ch2 ) // We have the same value
{
channel_count_detection_counter_ch2++; // Increment detection counter
}
else // We do not have the same value
{
channel_count_detection_counter_ch2 = 0; // Reset detection counter
}
previous_channel_count_ch2 = channel_count_ch2; // Load previous channel count with channel count
}
else // Detection counter >= Threshold
{
channel_count_detected_ch2 = true; // Channel count is now detected
}
channel_count_ready_ch2 = false; // Reset channel count detection ready flag
}
}
/*
//Reset throttle failsafe timeout
if( ppm1_channel == 5 ) throttle_timeout = 0;
CHECK_ERROR:
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Delay LED toggle
led_delay = 0;
#endif
*/
CHECK_DONE:
// Reset Watchdog Timer
wdt_reset();
// Set servo input missing flag false to indicate that we have received servo input signals
servo_input_missing = false;
// Store current servo input pins for next check
servo_pins_old = servo_pins;
// Start PPM generator if not already running
if( ppm_generator_active == false ) ppm_start();
/*
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Toggle RX LED when finished receiving servo pulses
if( ++led_delay > 64 ) // Toggle led every 64th time
{
PIND |= ( 1<< PD4 );
led_delay = 0;
}
#endif
// Throttle failsafe
if( throttle_timeout++ >= 128 )
{
// Reset throttle timeout
throttle_timeout = 0;
// Set throttle failsafe value
ppm[ 5 ] = PPM_THROTTLE_FAILSAFE;
}
//Has servo input changed while processing pins, if so we need to re-check pins
if( servo_pins != SERVO_INPUT ) goto CHECK_START;
*/
// Clear interrupt event from already processed pin changes
// PCIFR |= (1 << SERVO_INT_CLEAR_FLAG);
// Leave interrupt
return;
}
// -------------------------
// PPM redundancy mode END
// -------------------------
// ------------------------------------------------------------------------------
// PPM passtrough mode ( signal passtrough from channel 1 to ppm output pin)
// ------------------------------------------------------------------------------
if( servo_input_mode == PPM_PASSTROUGH_MODE )
{
// Has watchdog timer failsafe started PPM generator? If so we need to stop it.
if( ppm_generator_active )
{
// Stop PPM generator
ppm_stop();
}
// PPM (channel 1) input pin is high
if( SERVO_INPUT & 1 )
{
// Set PPM output pin high
PPM_PORT |= (1 << PPM_OUTPUT_PIN);
}
// PPM (channel 1) input pin is low
else
{
// Set PPM output pin low
PPM_PORT &= ~(1 << PPM_OUTPUT_PIN);
}
// Reset Watchdog Timer
wdt_reset();
// Set servo input missing flag false to indicate that we have received servo input signals
servo_input_missing = false;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Toggle TX LED at PPM passtrough
if( ++led_delay > 128 ) // Toggle every 128th pulse
{
// Toggle TX led
PIND |= ( 1<< PD5 );
led_delay = 0;
}
#endif
// Leave interrupt
return;
}
// ------------------------------------------------------------------------------
// PWM MODE (8 channels inputs)
// ------------------------------------------------------------------------------
CHECK_PINS_START: // Start of servo input check
// Store current servo input pins
servo_pins = SERVO_INPUT;
// Calculate servo input pin change mask
uint8_t servo_change = servo_pins ^ servo_pins_old;
// Set initial servo pin and channel
uint8_t servo_pin = 1;
uint8_t servo_channel = 0;
CHECK_PINS_LOOP: // Input servo pin check loop
// Check for pin change on current servo channel
if( servo_change & servo_pin )
{
// High (raising edge)
if( servo_pins & servo_pin )
{
servo_start[ servo_channel ] = servo_time;
}
else
// Low (falling edge)
{
// Get servo pulse width
uint16_t servo_width = servo_time - servo_start[ servo_channel ] - PPM_PRE_PULSE;
// Check that servo pulse signal is valid before sending to ppm encoder
if( servo_width > PWM_VAL_MAX ) goto CHECK_PINS_ERROR;
if( servo_width < PWM_VAL_MIN ) goto CHECK_PINS_ERROR;
// Calculate servo channel position in ppm[..]
uint8_t _ppm_channel = ( servo_channel << 1 ) + 1;
//Reset throttle failsafe timeout
if( _ppm_channel == 5 ) throttle_timeout = 0;
#ifdef _AVERAGE_FILTER_
// Average filter to smooth input jitter
servo_width += ppm[ _ppm_channel ];
servo_width >>= 1;
#endif
#ifdef _JITTER_FILTER_
// 0.5us cut filter to remove input jitter
int16_t ppm_tmp = ppm[ _ppm_channel ] - servo_width;
if( ppm_tmp == 1 ) goto CHECK_PINS_NEXT;
if( ppm_tmp == -1 ) goto CHECK_PINS_NEXT;
#endif
// Update ppm[..]
ppm[ _ppm_channel ] = servo_width;
}
}
CHECK_PINS_NEXT:
// Select next servo pin
servo_pin <<= 1;
// Select next servo channel
servo_channel++;
// Check channel and process if needed
if( servo_channel < PWM_CHANNELS ) goto CHECK_PINS_LOOP;
goto CHECK_PINS_DONE;
CHECK_PINS_ERROR:
// Used to indicate invalid servo input signals
servo_input_errors++;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Delay LED toggle
led_delay = 0;
#endif
goto CHECK_PINS_NEXT;
// All servo input pins has now been processed
CHECK_PINS_DONE:
// Reset Watchdog Timer
wdt_reset();
// Set servo input missing flag false to indicate that we have received servo input signals
servo_input_missing = false;
// Store current servo input pins for next check
servo_pins_old = servo_pins;
// Start PPM generator if not already running
if( ppm_generator_active == false ) ppm_start();
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Toggle RX LED when finished receiving servo pulses
if( ++led_delay > 64 ) // Toggle led every 64th time
{
PIND |= ( 1<< PD4 );
led_delay = 0;
}
#endif
// Throttle failsafe
if( throttle_timeout++ >= 128 )
{
// Reset throttle timeout
throttle_timeout = 0;
// Set throttle failsafe value
ppm[ 5 ] = PPM_THROTTLE_FAILSAFE;
}
//Has servo input changed while processing pins, if so we need to re-check pins
if( servo_pins != SERVO_INPUT ) goto CHECK_PINS_START;
// Clear interrupt event from already processed pin changes
PCIFR |= (1 << SERVO_INT_CLEAR_FLAG);
}
// ------------------------------------------------------------------------------
// PWM MODE END
// ------------------------------------------------------------------------------
// ------------------------------------------------------------------------------
// PPM OUTPUT - TIMER1 COMPARE INTERRUPT
// ------------------------------------------------------------------------------
ISR( PPM_INT_VECTOR )
{
// Current active ppm channel
static uint8_t ppm_channel = PPM_ARRAY_MAX - 1;
// Update timing for next PPM output pin toggle
PPM_COMPARE += ppm[ ppm_channel ];
// Select the next ppm channel
if( ++ppm_channel >= PPM_ARRAY_MAX )
{
ppm_channel = 0;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// Blink TX LED when PPM generator has finished a pulse train
PIND |= ( 1<< PD5 );
#endif
}
}
// ------------------------------------------------------------------------------
// ------------------------------------------------------------------------------
// PPM READ - INTERRUPT SAFE PPM SERVO CHANNEL READ
// ------------------------------------------------------------------------------
uint16_t ppm_read_channel( uint8_t channel )
{
// Limit channel to valid value
uint8_t _channel = channel;
if( _channel == 0 ) _channel = 1;
if( _channel > PWM_CHANNELS ) _channel = PWM_CHANNELS;
// Calculate ppm[..] position
uint8_t ppm_index = ( _channel << 1 ) + 1;
// Read ppm[..] in a non blocking interrupt safe manner
uint16_t ppm_tmp = ppm[ ppm_index ];
while( ppm_tmp != ppm[ ppm_index ] ) ppm_tmp = ppm[ ppm_index ];
// Return as normal servo value
return ppm_tmp + PPM_PRE_PULSE;
}
// ------------------------------------------------------------------------------
// ------------------------------------------------------------------------------
// PPM ENCODER INIT
// ------------------------------------------------------------------------------
void ppm_encoder_init( void )
{
// ATmegaXXU2 only init code
// ------------------------------------------------------------------------------
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// ------------------------------------------------------------------------------
// Reset Source check
// ------------------------------------------------------------------------------
if (MCUSR & 1) // Power-on Reset
{
MCUSR=0; // Clear MCU Status register
// custom code here
}
else if (MCUSR & 2) // External Reset
{
MCUSR=0; // Clear MCU Status register
// custom code here
}
else if (MCUSR & 4) // Brown-Out Reset
{
MCUSR=0; // Clear MCU Status register
brownout_reset=true;
}
else // Watchdog Reset
{
MCUSR=0; // Clear MCU Status register
// custom code here
}
// APM USB connection status UART MUX selector pin
// ------------------------------------------------------------------------------
USB_DDR |= (1 << USB_PIN); // Set USB pin to output
#endif
// USE JUMPER TO CHECK FOR INPUT MODE (pins 2&3 or 3&4 shorted)
// ------------------------------------------------------------------------------
if( servo_input_mode == JUMPER_SELECT_MODE )
{
// channel 3 status counter
uint8_t channel_2_status = 0;
uint8_t channel_4_status = 0;
// Set channel 2 to input
SERVO_DDR &= ~(1 << 1);
// Enable channel 2 pullup
SERVO_PORT |= (1 << 1);
// Set channel 4 to input
SERVO_DDR &= ~(1 << 3);
// Enable channel 4 pullup
SERVO_PORT |= (1 << 3);
// Set channel 3 to output
SERVO_DDR |= (1 << 2);
// Set channel 3 output low
SERVO_PORT &= ~(1 << 2);
_delay_us (10);
// Increment channel_2_status if channel 2 is set low by channel 3
if( ( SERVO_INPUT & (1 << 1) ) == 0 ) channel_2_status++;
// Increment channel_4_status if channel 4 is set low by channel 3
if( ( SERVO_INPUT & (1 << 3) ) == 0 ) channel_4_status++;
// Set channel 3 output high
SERVO_PORT |= (1 << 2);
_delay_us (10);
// Increment channel_2_status if channel 2 is set high by channel 3
if( ( SERVO_INPUT & (1 << 1) ) != 0 ) channel_2_status++;
// Increment channel_4_status if channel 4 is set high by channel 3
if( ( SERVO_INPUT & (1 << 3) ) != 0 ) channel_4_status++;
// Set channel 3 output low
SERVO_PORT &= ~(1 << 2);
_delay_us (10);
// Increment channel_2_status if channel 2 is set low by channel 3
if( ( SERVO_INPUT & (1 << 1) ) == 0 ) channel_2_status++;
// Increment channel_4_status if channel 4 is set low by channel 3
if( ( SERVO_INPUT & (1 << 3) ) == 0 ) channel_4_status++;
// Set servo input mode based on channel_2_status
if( channel_2_status == 3 ) servo_input_mode = PPM_PASSTROUGH_MODE;
if( channel_4_status == 3 ) servo_input_mode = PPM_REDUNDANCY_MODE;
else servo_input_mode = SERVO_PWM_MODE;
}
// RESET SERVO/PPM PINS AS INPUTS WITH PULLUPS
// ------------------------------------------------------------------------------
SERVO_DDR = 0;
SERVO_PORT |= 0xFF;
#if defined (__AVR_ATmega16U2__) || defined (__AVR_ATmega32U2__)
// on 32U2 set PD0 to be an output, and clear the bit. This tells
// the 2560 that USB is connected. The USB connection event fires
// later to set the right value
DDRD |= 1;
if (usb_connected) {
PORTD &= ~1;
} else {
PORTD |= 1;
}
#endif
// SERVO/PPM INPUT - PIN CHANGE INTERRUPT
// ------------------------------------------------------------------------------
if( servo_input_mode == SERVO_PWM_MODE )
{
// Set servo input interrupt pin mask to all 8 servo input channels
SERVO_INT_MASK = 0b11111111;
}
if( servo_input_mode == PPM_PASSTROUGH_MODE )
{
// Set servo input interrupt pin mask to servo input channel 1
SERVO_INT_MASK = 0b00000001;
}
if( servo_input_mode == PPM_REDUNDANCY_MODE )
{
// Set servo input interrupt pin mask to servo input channel 1 and 2
SERVO_INT_MASK = 0b00000011;
}
// Enable servo input interrupt
PCICR |= (1 << SERVO_INT_ENABLE);
// PPM OUTPUT PIN
// ------------------------------------------------------------------------------
// Set PPM pin to output
PPM_DDR |= (1 << PPM_OUTPUT_PIN);
// ------------------------------------------------------------------------------
// Enable watchdog interrupt mode
// ------------------------------------------------------------------------------
// Disable watchdog
wdt_disable();
// Reset watchdog timer
wdt_reset();
// Start timed watchdog setup sequence
WDTCSR |= (1<<WDCE) | (1<<WDE );
// Set 250 ms watchdog timeout and enable interrupt
WDTCSR = (1<<WDIE) | (1<<WDP2);
}
// ------------------------------------------------------------------------------