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108 lines
2.2 KiB
108 lines
2.2 KiB
#include <stdint.h>
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#include "i2c_simple.h"
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#include "mcp_adc.h"
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/* analog digital converter
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* scratchpad
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*
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* address: 1101000
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* read: conv data: 2 byte + config
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* - ignore first 2 bits, bit 3 = MSB/sign
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* - keeping reading always gets config byte
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* write: config
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*
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* configuration register:
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* - 0x15 continuos conversion, 14bit, gain x2 (page 16)
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* - 0x05 single conversion, 14bit, gain x2 (page 16)
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* bit 7 low -> new data, set to 1 on single conv mode to init
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*
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*/
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#define ADC_NEW_SAMPLE 0x80
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#define ADC_READ_DATA 0x40
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#define ADC_BITS_MASK 0x0c
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#define ADC_ADDR 0xD0 /* or 0x68 */
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uint8_t r[4];
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uint8_t curmode;
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uint8_t unread_data_available;
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void mcpadc_init(uint8_t mode)
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{
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int written = i2c_write(ADC_ADDR, 1, &mode);
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if(written!=1){
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for(;;); //TODO: error reporting
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}
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curmode = mode;
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}
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uint8_t mcpadc_has_new_data()
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{
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/* this assumes that the first RDY bit read after the sample data indicates the old/new state of the sample we just read */
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if(unread_data_available){
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// we already have new data, don't overwrite that by reading more
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return unread_data_available;
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}
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#if ADC_ENABLE_18_BIT_MODE
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if(curmode & ADC_BITS_MASK == ADC_BITS_18)
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{
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i2c_read(ADC_ADDR, 4, r);
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curmode = r[3];
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}
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else
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#else
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{
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i2c_read(ADC_ADDR, 3, r);
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curmode = r[2];
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}
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#endif
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if(!(curmode & ADC_NEW_SAMPLE)){ // if the /RDY bit reads 0, we just read a new sample
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unread_data_available = 1;
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}
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return unread_data_available;
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}
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#if ADC_ENABLE_18_BIT_MODE
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int32_t mcpadc_get_data()
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{
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if(!unread_data_available){
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return 0;
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}
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int32_t value = 0;
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if(r[0] & 0x80) {value = 0xffff;}
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value = (value << 16) | (r[0] << 8) | r[1];
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if((uint8_t) r[3] & ADC_BITS_MASK == ADC_BITS_18)
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{
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value = (value << 8) | r[2];
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}
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curmode |= (ADC_NEW_SAMPLE);
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unread_data_available = 0;
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return value;
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}
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#else
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int16_t mcpadc_get_data()
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{
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if(!unread_data_available){
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return 0;
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}
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int16_t value = (r[0] << 8) | r[1];
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curmode |= (ADC_NEW_SAMPLE & ADC_READ_DATA);
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unread_data_available = 0;
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return value;
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}
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#endif
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void mcpadc_start_conv(void)
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{
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r[3] = curmode | ADC_NEW_SAMPLE;
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i2c_write(ADC_ADDR, 1, &(r[3]));
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// curmode |= (ADC_NEW_SAMPLE & ADC_READ_DATA);/* you asked for a new sample - no you won't get the old one */
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unread_data_available = 0;
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}
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