#include <sys/types.h>

/* analog digital converter
 * scratchpad
 * 
 * address: 1101000
 * read: conv data: 2 byte + config
 * - ignore first 2 bits, bit 3 = MSB/sign
 * - keeping reading always gets config byte
 * write: config
 * 
 * configuration register:
 * - 0x15 continuos conversion, 14bit, gain x2 (page 16)
 * - 0x05 single conversion, 14bit, gain x2 (page 16)
 * bit 7 low -> new data, set to 1 on single conv mode to init
 *
 */

#define ADC_NEW_SAMPLE 0x80
#define ADC_BITS_MASK 0x0c

#define ADC_ADDR 0xD0 /* or 0x68 */

void mcpadc_init(uint8_t mode)
{
	i2c_write(ADC_ADDR, 1, &mode))
}

uint8_t mcpadc_has_new_data()
{
	uint8_t r[4];
	i2c_read(ADC_ADDR, 4, r)/* 4 bytes are only needed in 18 bit mode */
	return r[3] & ADC_NEW_SAMPLE;
}

#if ADC_ENABLE_18_BIT_MODE
int32_t mcpadc_get_data()
{
	uint8_t r[4] = 0;
	int32_t value = 0;
	i2c_read(ADC_ADDR, 4, r);/* reading 4 bytes guarantees us one config byte */
	if(r[0] & 0x80) {value = 0xffff;}
	value = (value << 16) | (r[0] << 8) | r[1];/*endianess ???*/
	if((uint8_t) r[3] & ADC_BITS_MASK == ADC_BITS_18)
	{
		value = (value << 8) | r[3];
	}
	return value;
}
#else
int16_t mcpadc_get_data()
{
	uint8_t r[2] = 0;
	i2c_read(ADC_ADDR, 2, r);/* this will NOT work in 18 bit mode */
	int16_t value = (r[0] << 8) | r[1];/*endianess ???*/
	return r;
}
#endif

void mcpadc_start_conv()
{
	uint8_t r[4];
	i2c_read(ADC_ADDR, 4, r);
	r[3] |= ADC_NEW_SAMPLE;
	i2c_write(ADC_ADDR, 1, &(r[3]));
}