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Reorder the channels 

Fix overflow issue

git-svn-id: https://arducopter.googlecode.com/svn/trunk@449 f9c3cf11-9bcb-44bc-f272-b75c42450872
This commit is contained in:
deweibel 2010-09-10 20:41:41 +00:00
parent 80bc831363
commit 72d031b4b5
2 changed files with 64 additions and 46 deletions
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86
libraries/APM_ADC/APM_ADC.cpp
View File

@ -2,6 +2,12 @@
APM_ADC.cpp - ADC ADS7844 Library for Ardupilot Mega APM_ADC.cpp - ADC ADS7844 Library for Ardupilot Mega
Code by Jordi Muñoz and Jose Julio. DIYDrones.com Code by Jordi Muñoz and Jose Julio. DIYDrones.com
Modified by John Ihlein 6/19/2010 to:
1)Prevent overflow of adc_counter when more than 8 samples collected between reads. Probably
only an issue on initial read of ADC at program start.
2)Reorder analog read order as follows:
p, q, r, ax, ay, az
This library is free software; you can redistribute it and/or This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either License as published by the Free Software Foundation; either
@ -21,14 +27,18 @@
Init() : Initialization of interrupts an Timers (Timer2 overflow interrupt) Init() : Initialization of interrupts an Timers (Timer2 overflow interrupt)
Ch(ch_num) : Return the ADC channel value Ch(ch_num) : Return the ADC channel value
On Ardupilot Mega Hardware: // HJI - Input definitions. USB connector assumed to be on the left, Rx and servo
Channel 1 : Gyro Z // connector pins to the rear. IMU shield components facing up. These are board
Channel 2 : Gyro X // referenced sensor inputs, not device referenced.
Channel 3 : Gyro Y On Ardupilot Mega Hardware, oriented as described above:
Channel 4 : Acc X Chennel 0 : yaw rate, r
Channel 5 : Acc Y Channel 1 : roll rate, p
Channel 6 : Acc Z Channel 2 : pitch rate, q
Channel 7 : Differential pressure sensor Channel 3 : x/y gyro temperature
Channel 4 : x acceleration, aX
Channel 5 : y acceleration, aY
Channel 6 : z acceleration, aZ
Channel 7 : Differential pressure sensor port
*/ */
extern "C" { extern "C" {
@ -40,10 +50,13 @@ extern "C" {
#include "APM_ADC.h" #include "APM_ADC.h"
// HJI - changed read order to p, q, r, ax, ay, az, gyro temperature, JP5 pin 3
// Commands for reading ADC channels on ADS7844 // Commands for reading ADC channels on ADS7844
const unsigned char adc_cmd[9]= { 0x87, 0xC7, 0x97, 0xD7, 0xA7, 0xE7, 0xB7, 0xF7, 0x00 }; // Note change in read order pRate qRate rRate aX aY aZ temp JP5
volatile long adc_value[8]; // ADC Input Channel Ch1 Ch2 Ch0 Ch4 Ch5 Ch6 Ch3 Ch7
volatile unsigned char adc_counter[8]; const unsigned char adc_cmd[9] = { 0xC7, 0x97, 0x87, 0xA7, 0xE7, 0xB7, 0xD7, 0xF7, 0x00 };
volatile long adc_value[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
volatile unsigned char adc_counter[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
unsigned char ADC_SPI_transfer(unsigned char data) unsigned char ADC_SPI_transfer(unsigned char data)
{ {
@ -63,19 +76,24 @@ ISR (TIMER2_OVF_vect)
uint8_t ch; uint8_t ch;
unsigned int adc_tmp; unsigned int adc_tmp;
//bit_set(PORTL,6); // To test performance //bit_set(PORTL,6); // To test performance
bit_clear(PORTC,4); // Enable Chip Select (PIN PC4) bit_clear(PORTC,4); // Enable Chip Select (PIN PC4)
ADC_SPI_transfer(adc_cmd[0]); // Command to read the first channel ADC_SPI_transfer(adc_cmd[0]); // Command to read the first channel
for (ch=0;ch<8;ch++) for (ch=0;ch<8;ch++)
{ {
adc_tmp = ADC_SPI_transfer(0)<<8; // Read first byte if (adc_counter[ch] >= 17) // HJI - Added this to prevent
adc_tmp |= ADC_SPI_transfer(adc_cmd[ch+1]); // Read second byte and send next command { // overflow of adc_value
adc_value[ch] += adc_tmp>>3; // Shift to 12 bits adc_value[ch] = 0;
adc_counter[ch]++; // Number of samples adc_counter[ch] = 0;
}
adc_tmp = ADC_SPI_transfer(0)<<8; // Read first byte
adc_tmp |= ADC_SPI_transfer(adc_cmd[ch+1]); // Read second byte and send next command
adc_value[ch] += adc_tmp>>3; // Shift to 12 bits
adc_counter[ch]++; // Number of samples
} }
bit_set(PORTC,4); // Disable Chip Select (PIN PC4) bit_set(PORTC,4); // Disable Chip Select (PIN PC4)
//bit_clear(PORTL,6); // To test performance //bit_clear(PORTL,6); // To test performance
TCNT2 = 104; // 400 Hz TCNT2 = 104; // 400 Hz
} }
@ -91,26 +109,26 @@ void APM_ADC_Class::Init(void)
pinMode(ADC_CHIP_SELECT,OUTPUT); pinMode(ADC_CHIP_SELECT,OUTPUT);
digitalWrite(ADC_CHIP_SELECT,HIGH); // Disable device (Chip select is active low) digitalWrite(ADC_CHIP_SELECT,HIGH); // Disable device (Chip select is active low)
// Setup Serial Port2 in SPI mode // Setup Serial Port2 in SPI mode
UBRR2 = 0; UBRR2 = 0;
DDRH |= (1<<PH2); // SPI clock XCK2 (PH2) as output. This enable SPI Master mode DDRH |= (1<<PH2); // SPI clock XCK2 (PH2) as output. This enable SPI Master mode
// Set MSPI mode of operation and SPI data mode 0. // Set MSPI mode of operation and SPI data mode 0.
UCSR2C = (1<<UMSEL21)|(1<<UMSEL20); //|(0<<UCPHA2)|(0<<UCPOL2); UCSR2C = (1<<UMSEL21)|(1<<UMSEL20); //|(0<<UCPHA2)|(0<<UCPOL2);
// Enable receiver and transmitter. // Enable receiver and transmitter.
UCSR2B = (1<<RXEN2)|(1<<TXEN2); UCSR2B = (1<<RXEN2)|(1<<TXEN2);
// Set Baud rate // Set Baud rate
UBRR2 = 2; // SPI clock running at 2.6MHz UBRR2 = 2; // SPI clock running at 2.6MHz
// Enable Timer2 Overflow interrupt to capture ADC data // Enable Timer2 Overflow interrupt to capture ADC data
TIMSK2 = 0; // Disable interrupts TIMSK2 = 0; // Disable interrupts
TCCR2A = 0; // normal counting mode TCCR2A = 0; // normal counting mode
TCCR2B = _BV(CS21)|_BV(CS22); // Set prescaler of 256 TCCR2B = _BV(CS21)|_BV(CS22); // Set prescaler of 256
TCNT2 = 0; TCNT2 = 0;
TIFR2 = _BV(TOV2); // clear pending interrupts; TIFR2 = _BV(TOV2); // clear pending interrupts;
TIMSK2 = _BV(TOIE2) ; // enable the overflow interrupt TIMSK2 = _BV(TOIE2) ; // enable the overflow interrupt
} }
// Read one channel value // Read one channel value
@ -118,12 +136,12 @@ int APM_ADC_Class::Ch(unsigned char ch_num)
{ {
int result; int result;
cli(); // We stop interrupts to read the variables cli(); // We stop interrupts to read the variables
if (adc_counter[ch_num]>0) if (adc_counter[ch_num]>0)
result = adc_value[ch_num]/adc_counter[ch_num]; result = adc_value[ch_num]/adc_counter[ch_num]);
else else
result = 0; result = 0;
adc_value[ch_num] = 0; // Initialize for next reading adc_value[ch_num] = 0; // Initialize for next reading
adc_counter[ch_num] = 0; adc_counter[ch_num] = 0;
sei(); sei();
return(result); return(result);

10
libraries/APM_ADC/APM_ADC.h
View File

@ -1,13 +1,13 @@
#ifndef APM_ADC_h #ifndef APM_ADC_h
#define APM_ADC_h #define APM_ADC_h
#define bit_set(p,m) ((p) |= (1<<m)) #define bit_set(p,m) ((p) |= ( 1<<m))
#define bit_clear(p,m) ((p) &= ~(1<<m)) #define bit_clear(p,m) ((p) &= ~(1<<m))
// We use Serial Port 2 in SPI Mode // We use Serial Port 2 in SPI Mode
#define ADC_DATAOUT 51 // MOSI #define ADC_DATAOUT 51 // MOSI
#define ADC_DATAIN 50 // MISO #define ADC_DATAIN 50 // MISO
#define ADC_SPICLOCK 52 // SCK #define ADC_SPICLOCK 52 // SCK
#define ADC_CHIP_SELECT 33 // PC4 9 // PH6 Puerto:0x08 Bit mask : 0x40 #define ADC_CHIP_SELECT 33 // PC4 9 // PH6 Puerto:0x08 Bit mask : 0x40
class APM_ADC_Class class APM_ADC_Class
@ -16,7 +16,7 @@ class APM_ADC_Class
public: public:
APM_ADC_Class(); // Constructor APM_ADC_Class(); // Constructor
void Init(); void Init();
int Ch(unsigned char ch_num); float Ch(unsigned char ch_num); // HJI Changed from int to float
}; };
extern APM_ADC_Class APM_ADC; extern APM_ADC_Class APM_ADC;