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Reorder the channels

Browse Source 
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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42
libraries/APM_ADC/APM_ADC.cpp
View File

@ -2,6 +2,12 @@
APM_ADC.cpp - ADC ADS7844 Library for Ardupilot Mega
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
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
@ -21,14 +27,18 @@
Init() : Initialization of interrupts an Timers (Timer2 overflow interrupt)
Ch(ch_num) : Return the ADC channel value
On Ardupilot Mega Hardware:
Channel 1 : Gyro Z
Channel 2 : Gyro X
Channel 3 : Gyro Y
Channel 4 : Acc X
Channel 5 : Acc Y
Channel 6 : Acc Z
Channel 7 : Differential pressure sensor
// HJI - Input definitions. USB connector assumed to be on the left, Rx and servo
// connector pins to the rear. IMU shield components facing up. These are board
// referenced sensor inputs, not device referenced.
On Ardupilot Mega Hardware, oriented as described above:
Chennel 0 : yaw rate, r
Channel 1 : roll rate, p
Channel 2 : pitch rate, q
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" {
@ -40,10 +50,13 @@ extern "C" {
#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
const unsigned char adc_cmd[9]= { 0x87, 0xC7, 0x97, 0xD7, 0xA7, 0xE7, 0xB7, 0xF7, 0x00 };
volatile long adc_value[8];
volatile unsigned char adc_counter[8];
// Note change in read order pRate qRate rRate aX aY aZ temp JP5
// ADC Input Channel Ch1 Ch2 Ch0 Ch4 Ch5 Ch6 Ch3 Ch7
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)
{
@ -68,6 +81,11 @@ ISR (TIMER2_OVF_vect)
ADC_SPI_transfer(adc_cmd[0]); // Command to read the first channel
for (ch=0;ch<8;ch++)
{
if (adc_counter[ch] >= 17) // HJI - Added this to prevent
{ // overflow of adc_value
adc_value[ch] = 0;
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
@ -120,7 +138,7 @@ int APM_ADC_Class::Ch(unsigned char ch_num)
cli(); // We stop interrupts to read the variables
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
result = 0;
adc_value[ch_num] = 0; // Initialize for next reading

2
libraries/APM_ADC/APM_ADC.h
View File

@ -16,7 +16,7 @@ class APM_ADC_Class
public:
APM_ADC_Class(); // Constructor
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;