Mirror/ardupilot
5
0
Fork 0
mirror of https://github.com/ArduPilot/ardupilot synced 2025-01-20 07:38:28 -04:00
Code Issues Packages Projects Releases Wiki Activity

ADC Library - reimplement overflow

Browse Source 
git-svn-id: https://arducopter.googlecode.com/svn/trunk@1832 f9c3cf11-9bcb-44bc-f272-b75c42450872
This commit is contained in:
mich146@hotmail.com 2011-03-31 14:19:59 +00:00
parent 72fc8a1f51
commit bae1c531d0
1 changed files with 10 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
libraries/AP_ADC/AP_ADC_ADS7844.cpp
View File

@ -53,7 +53,7 @@ extern "C" {
// Commands for reading ADC channels on ADS7844 // Commands for reading ADC channels on ADS7844
static const unsigned char adc_cmd[9]= { 0x87, 0xC7, 0x97, 0xD7, 0xA7, 0xE7, 0xB7, 0xF7, 0x00 }; static const unsigned char adc_cmd[9]= { 0x87, 0xC7, 0x97, 0xD7, 0xA7, 0xE7, 0xB7, 0xF7, 0x00 };
static volatile long adc_value[8] = { 0, 0, 0, 0, 0, 0, 0, 0 }; static volatile unsigned int adc_value[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
static volatile unsigned char adc_counter[8] = { 0, 0, 0, 0, 0, 0, 0, 0 }; static volatile unsigned char adc_counter[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
static unsigned char ADC_SPI_transfer(unsigned char data) static unsigned char ADC_SPI_transfer(unsigned char data)
@ -79,10 +79,10 @@ ISR (TIMER2_OVF_vect)
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++)
{ {
if (adc_counter[ch] >= 17) // HJI - Added this to prevent if (adc_counter[ch] >= 16) // To prevent overflow of adc_value
{ // overflow of adc_value { //
adc_value[ch] = 0; adc_value[ch] /= 2;
adc_counter[ch] = 0; adc_counter[ch] /= 2;
} }
adc_tmp = ADC_SPI_transfer(0)<<8; // Read first byte 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_tmp |= ADC_SPI_transfer(adc_cmd[ch+1]); // Read second byte and send next command
@ -134,11 +134,14 @@ int AP_ADC_ADS7844::Ch(unsigned char ch_num)
{ {
int result; int result;
cli(); // We stop interrupts to read the variables while(adc_counter[ch_num] < 2) { } // Wait for at least 2 samples in accumlator
cli();
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();