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// ------------------------------------------------------------------------------------------------------------------------------------------------------------
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// ArduPPM Version v0.9.87
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// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// ARDUCOPTER 2 : PPM ENCODER for AT Mega 328p and APM v1.4 Boards
// By:John Arne Birkeland - 2011
//
// By: Olivier ADLER - 2011 - APM v1.4 adaptation and testing
//
// Compiled with Atmel AVR Studio 4.0 / AVR GCC
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// Changelog //
//
// Code based on John Arne PPM v1 encoder. Mux / Led / Failsafe control from Olivier ADLER.
// Adaptation to APM v1.4 / ATMEGA 328p by Olivier ADLER, with great code base, help and advices from John Arne.
//
// 0.9.0 -> 0.9.4 : experimental versions. Not publicly available. Jitter problems, good reliability.
//
// New PPM code base V2 from John Arne designed for 32u2 AVRs
//
// 0.9.5 : first reliable and jitter free version based on new John PPM V2 code and Olivier interrupt nesting idea.
// 0.9.6 : enhanced jitter free version with non bloking servo interrupt and ultra fast ppm generator interrupt(John's ideas)
// 0.9.7 : mux (passthrough mode) switchover reliability enhancements and error reporting improvements.
// 0.9.75 : implemented ppm_encoder.h library with support for both atmega328p and atmega32u2 chips
// 0.9.76 : timers 0 and 2 replaced by a delayed loop for simplicity. Timer 0 and 2 are now free for use.
// reworked error detection with settable time window, errors threshold and Led delay
// 0.9.77 : Implemented ppm_encoder.h into latest version.
// 0.9.78 : Implemented optimzed assembly compare interrupt
// 0.9.79 : Removed Non Blocking attribute for servo input interrupt
// 0.9.80 : Removed non blocking for compare interrupt, added optionnal jitter filter and optionnal non blocking attribute for assembly version of compare interrupt
// 0.9.81 : Added PPM PASSTROUGH Mode and LED Codes function to report special modes
// 0.9.82 : LED codes function simplification
// 0.9.83 : Implemented PPM passtrough failsafe
// 0.9.84 : Corrected pin and port names in Encoder-PPM.c according to #define for Mega32U2 compatibility
// 0.9.85 : Added brownout reset detection flag
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// 0.9.86 : Added a #define to disable Radio Passthrough mode (hardware failsafe for Arduplane)
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// 0.9.87 : #define correction for radio passthrough (was screwed up).
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// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// PREPROCESSOR DIRECTIVES
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
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# include "..\Libraries\ppm_encoder.h"
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# include <util/delay.h>
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# define ERROR_THRESHOLD 2 // Number of servo input errors before alerting
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# define ERROR_DETECTION_WINDOW 3000 * LOOP_TIMER_10MS // Detection window for error detection (default to 30s)
# define ERROR_CONDITION_DELAY 500 * LOOP_TIMER_10MS // Servo error condition LED delay (LED blinking duration)
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# define PASSTHROUGH_MODE_ENABLED // Comment this line to remove CH8 radio passthrough mode support (hardware failsafe for Arduplane)
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# define PASSTHROUGH_CHANNEL 8 * 2 // Channel for passthrough mode selection
# define PASSTHROUGH_CHANNEL_OFF_US ONE_US * 1600 - PPM_PRE_PULSE // Passthrough off threshold
# define PASSTHROUGH_CHANNEL_ON_US ONE_US * 1800 - PPM_PRE_PULSE // Passthrough on threshold
# define THROTTLE_CHANNEL 3 * 2 // Throttle Channel
# define THROTTLE_CHANNEL_LED_TOGGLE_US ONE_US * 1200 - PPM_PRE_PULSE // Throttle Channel Led toggle threshold
# define LED_LOW_BLINKING_RATE 125 * LOOP_TIMER_10MS // Led blink rate for low throttle position (half period)
// Timers
# define TIMER0_10MS 156 // Timer0 ticks for 10 ms duration
# define TIMER1_10MS 20000 // Timer1 ticks for 10 ms duration
# define TIMER2_100MS 1562 // Timer2 ticks for 100 ms duration
# define LOOP_TIMER_10MS 10 // Loop timer ticks for 10 ms duration
// LED Code
# define SPACE_SHORT_DURATION 40 * LOOP_TIMER_10MS // Space after short symbol
# define SPACE_LONG_DURATION 75 * LOOP_TIMER_10MS // Space after long symbol
# define SYMBOL_SHORT_DURATION 20 * LOOP_TIMER_10MS // Short symbol duration
# define SYMBOL_LONG_DURATION 100 * LOOP_TIMER_10MS // Long symbol duration
# define INTER_CODE_DURATION 150 * LOOP_TIMER_10MS // Inter code duration
# define INTER_CODE 0 // Symbols value for coding
# define SHORT_SYMBOL 1
# define LONG_SYMBOL 2
# define SHORT_SPACE 3
# define LONG_SPACE 4
# define LOOP 5
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// PPM ENCODER INIT AND AUXILIARY TASKS
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
int main ( void )
{
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// LOCAL VARIABLES
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
bool init = true ; // We are inside init sequence
bool mux_passthrough = false ; // Mux passthrough mode status Flag : passthrough is off
uint16_t led_acceleration ; // Led acceleration based on throttle stick position
bool servo_error_condition = false ; // Servo signal error condition
static uint16_t servo_error_detection_timer = 0 ; // Servo error detection timer
static uint16_t servo_error_condition_timer = 0 ; // Servo error condition timer
static uint16_t blink_led_timer = 0 ; // Blink led timer
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# ifdef PASSTHROUGH_MODE_ENABLED
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static uint8_t mux_timer = 0 ; // Mux timer
static uint8_t mux_counter = 0 ; // Mux counter
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static int8_t mux_check = 0 ;
static uint16_t mux_ppm = 500 ;
# endif
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static uint16_t led_code_timer = 0 ; // Blink Code Timer
static uint8_t led_code_symbol = 0 ; // Blink Code current symbol
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// LOCAL FUNCTIONS
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// ------------------------------------------------------------------------------
// Led blinking (non blocking) function
// ------------------------------------------------------------------------------
uint8_t blink_led ( uint16_t half_period ) // ( half_period max = 65 s )
{
blink_led_timer + + ;
if ( blink_led_timer < half_period ) // If half period has not been reached
{
return 0 ; // Exit timer function and return 0
}
else // half period reached - LED Toggle
{
PPM_PORT ^ = ( 1 < < PB0 ) ; // Toggle status LED
blink_led_timer = 0 ; // Blink led timer reset
return 1 ; // half period reached - Exit timer function and return 1
}
}
// ------------------------------------------------------------------------------
// Led code (non blocking) function
// ------------------------------------------------------------------------------
void blink_code_led ( uint8_t code )
{
const uint8_t coding [ 2 ] [ 14 ] = {
// PPM_PASSTROUGH_MODE
{ INTER_CODE , LONG_SYMBOL , LONG_SPACE , SHORT_SYMBOL , SHORT_SPACE , SHORT_SYMBOL , LOOP } ,
// JETI_MODE
{ INTER_CODE , LONG_SYMBOL , LONG_SPACE , SHORT_SYMBOL , SHORT_SPACE , SHORT_SYMBOL , SHORT_SPACE , SHORT_SYMBOL , LOOP }
} ;
led_code_timer + + ;
switch ( coding [ code - 2 ] [ led_code_symbol ] )
{
case INTER_CODE :
if ( led_code_timer < ( INTER_CODE_DURATION ) ) return ;
else PPM_PORT | = ( 1 < < PB0 ) ; // Enable status LED
break ;
case LONG_SYMBOL : // Long symbol
if ( led_code_timer < ( SYMBOL_LONG_DURATION ) ) return ;
else PPM_PORT & = ~ ( 1 < < PB0 ) ; // Disable status LED
break ;
case SHORT_SYMBOL : // Short symbol
if ( led_code_timer < ( SYMBOL_SHORT_DURATION ) ) return ;
else PPM_PORT & = ~ ( 1 < < PB0 ) ; // Disable status LED
break ;
case SHORT_SPACE : // Short space
if ( led_code_timer < ( SPACE_SHORT_DURATION ) ) return ;
else PPM_PORT | = ( 1 < < PB0 ) ; // Enable status LED
break ;
case LONG_SPACE : // Long space
if ( led_code_timer < ( SPACE_LONG_DURATION ) ) return ;
else PPM_PORT | = ( 1 < < PB0 ) ; // Enable status LED
break ;
case LOOP : // Loop to code start
led_code_symbol = 0 ;
return ;
break ;
}
led_code_timer = 0 ; // Code led timer reset
led_code_symbol + + ; // Next symbol
return ; // LED code function return
}
// ------------------------------------------------------------------------------
// ppm reading helper - interrupt safe and non blocking function
// ------------------------------------------------------------------------------
uint16_t ppm_read ( uint8_t channel )
{
uint16_t ppm_tmp = ppm [ channel ] ;
while ( ppm_tmp ! = ppm [ channel ] ) ppm_tmp = ppm [ channel ] ;
return ppm_tmp ;
}
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// INITIALISATION CODE
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// ------------------------------------------------------------------------------
// Reset Source checkings
// ------------------------------------------------------------------------------
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
}
// ------------------------------------------------------------------------------
// Servo input and PPM generator init
// ------------------------------------------------------------------------------
ppm_encoder_init ( ) ;
// ------------------------------------------------------------------------------
// Outputs init
// ------------------------------------------------------------------------------
PPM_DDR | = ( 1 < < PB0 ) ; // Set LED pin (PB0) to output
PPM_DDR | = ( 1 < < PB1 ) ; // Set MUX pin (PB1) to output
PPM_DDR | = ( 1 < < PPM_OUTPUT_PIN ) ; // Set PPM pin (PPM_OUTPUT_PIN, OC1B) to output
// ------------------------------------------------------------------------------
// Timer0 init (normal mode) used for LED control and custom code
// ------------------------------------------------------------------------------
TCCR0A = 0x00 ; // Clock source: System Clock
TCCR0B = 0x05 ; // Set 1024x prescaler - Clock value: 15.625 kHz - 16 ms max time
TCNT0 = 0x00 ;
OCR0A = 0x00 ; // OC0x outputs: Disconnected
OCR0B = 0x00 ;
TIMSK0 = 0x00 ; // Timer 1 interrupt disable
// ------------------------------------------------------------------------------
// Enable global interrupt
// ------------------------------------------------------------------------------
sei ( ) ; // Enable Global interrupt flag
// ------------------------------------------------------------------------------
// Disable radio passthrough (mux chip A/B control)
// ------------------------------------------------------------------------------
PPM_PORT | = ( 1 < < PB1 ) ; // Set PIN B1 to disable Radio passthrough (mux)
// ------------------------------------------------------------------------------
// Check for first valid servo signal
// ------------------------------------------------------------------------------
while ( 1 )
{
if ( servo_error_condition | | servo_input_missing ) // We have an error
{
blink_led ( 6 * LOOP_TIMER_10MS ) ; // Status LED very fast blink if invalid servo input or missing signal
}
else // We are running normally
{
init = false ; // initialisation is done,
switch ( servo_input_mode )
{
case SERVO_PWM_MODE : // Normal PWM mode
goto PWM_LOOP ;
break ;
case PPM_PASSTROUGH_MODE : // PPM_PASSTROUGH_MODE
goto PPM_PASSTHROUGH_LOOP ;
break ;
default : // Normal PWM mode
goto PWM_LOOP ;
break ;
}
}
_delay_us ( 970 ) ; // Slow down while loop
}
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
// AUXILIARY TASKS
// ------------------------------------------------------------------------------------------------------------------------------------------------------------
PWM_LOOP : // SERVO_PWM_MODE
while ( 1 )
{
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# ifdef PASSTHROUGH_MODE_ENABLED
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// ------------------------------------------------------------------------------
// Radio passthrough control (mux chip A/B control)
// ------------------------------------------------------------------------------
mux_timer + + ; // Increment mux timer
if ( mux_timer > ( 3 * LOOP_TIMER_10MS ) ) // Check Passthrough Channel every 30ms
{
mux_timer = 0 ; // Reset mux timer
if ( mux_counter + + < 5 ) // Check passthrough channel position 5 times
{
mux_ppm = ppm_read ( PASSTHROUGH_CHANNEL - 1 ) ; // Safely read passthrough channel ppm position
if ( mux_ppm < ( PASSTHROUGH_CHANNEL_OFF_US ) ) // Check ppm value and update validation counter
{
mux_check - = 1 ;
}
else if ( mux_ppm > ( PASSTHROUGH_CHANNEL_ON_US ) )
{
mux_check + = 1 ;
}
}
else // Check
{
switch ( mux_check ) // If all 5 checks are the same, update mux status flag
{
case - 5 :
mux_passthrough = false ;
PPM_PORT | = ( 1 < < PB1 ) ; // Set PIN B1 (Mux) to disable Radio passthrough
break ;
case 5 :
mux_passthrough = true ;
PPM_PORT & = ~ ( 1 < < PB1 ) ; // Reset PIN B1 (Mux) to enable Radio passthrough
break ;
}
mux_check = 0 ; // Reset mux validation counter
mux_counter = 0 ; // Reset mux counter
}
}
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# endif
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// ------------------------------------------------------------------------------
// Status LED control
// ------------------------------------------------------------------------------
if ( servo_error_condition | | servo_input_missing ) // We have an error
{
blink_led ( 6 * LOOP_TIMER_10MS ) ; // Status LED very fast blink if invalid servo input or missing signal
}
else // We are running normally
{
if ( mux_passthrough = = false ) // Normal mode : status LED toggle speed from throttle position
{
led_acceleration = ( ppm [ THROTTLE_CHANNEL - 1 ] - ( PPM_SERVO_MIN ) ) / 2 ;
blink_led ( LED_LOW_BLINKING_RATE - led_acceleration ) ;
}
else // Passthrough mode : status LED never flashing
{
// Enable status LED if throttle > THROTTLE_CHANNEL_LED_TOGGLE_US
if ( ppm [ THROTTLE_CHANNEL - 1 ] > ( THROTTLE_CHANNEL_LED_TOGGLE_US ) )
{
PPM_PORT | = ( 1 < < PB0 ) ;
}
// Disable status LED if throttle <= THROTTLE_CHANNEL_LED_TOGGLE_US
else if ( ppm [ THROTTLE_CHANNEL - 1 ] < = ( THROTTLE_CHANNEL_LED_TOGGLE_US ) )
{
PPM_PORT & = ~ ( 1 < < PB0 ) ;
}
}
}
// ------------------------------------------------------------------------------
// Servo input error detection
// ------------------------------------------------------------------------------
// If there are too many errors during the detection time window, then trig servo error condition
if ( servo_input_errors > 0 ) // Start error rate checking if an error did occur
{
if ( servo_error_detection_timer > ( ERROR_DETECTION_WINDOW ) ) // If 10s delay reached
{
servo_error_detection_timer = 0 ; // Reset error detection timer
servo_input_errors = 0 ; // Reset servo input error counter
}
else // If 10s delay is not reached
{
servo_error_detection_timer + + ; // Increment servo error timer value
if ( servo_input_errors > = ( ERROR_THRESHOLD ) ) // If there are too many errors
{
servo_error_condition = true ; // Enable error condition flag
servo_input_errors = 0 ; // Reset servo input error counter
servo_error_detection_timer = 0 ; // Reset servo error detection timer
servo_error_condition_timer = 0 ; // Reset servo error condition timer
}
}
}
// Servo error condition flag (will control blinking LED)
if ( servo_error_condition = = true ) // We are in error condition
{
if ( servo_error_condition_timer > ( ERROR_CONDITION_DELAY ) ) // If 3s delay reached
{
servo_error_condition_timer = 0 ; // Reset servo error condition timer
servo_error_condition = false ; // Reset servo error condition flag (Led will stop very fast blink)
}
else servo_error_condition_timer + + ; // If 3s delay is not reached update servo error condition timer value
}
_delay_us ( 950 ) ; // Slow down while loop
} // PWM Loop end
PPM_PASSTHROUGH_LOOP : // PPM_PASSTROUGH_MODE
while ( 1 )
{
// ------------------------------------------------------------------------------
// Status LED control
// ------------------------------------------------------------------------------
if ( servo_input_missing ) // We have an error
{
blink_led ( 6 * LOOP_TIMER_10MS ) ; // Status LED very fast blink if invalid servo input or missing signal
}
else // We are running normally
{
blink_code_led ( PPM_PASSTROUGH_MODE ) ; // Blink LED according to mode 2 code (one long, two shorts).
}
_delay_us ( 970 ) ; // Slow down this loop
} // PPM_PASSTHROUGH Loop end
} // main function end
