zoom/firmware/calibrate.c

#include "config.h"
#include "calibrate.h"
#include "util.h"
#include "adc.h"
#include "dac.h"

static float scale;  /* delta(DAC) / delta(ADC) */

/* Initialize.  Assume some relatively-safe scaling if no calibration is run */
void calibrate_init(void)
{
	scale = 0;
}

/* Seek with the DAC to reach a specific ADC value, adjusting
 * calibration if necessary */
uint16_t seek(int16_t desired)
{
	int32_t dac = 32768;
	int16_t actual;
	int32_t delta = 0;

	while (1)
	{
		/* get current location */
		dac_write(dac);
		msleep(1);
		actual = adc_get();

		/* adjust scaling to match the jump we just saw */
		if (delta) {
			
		}

		if (actual == desired)
			return dac;

		/* figure out how much to change the DAC */
		delta = (desired - actual) * scale;

		
		dac -= (desired - actual) * scale;

		
	}
	uint16_t dac = 0;
	dac_write(0x8000

}

/* Perform calibration */
void do_calibrate(void)
{
	uint16_t daczero, x;
	float x1, y1, x2, y2;

	/* Zero ADC */
	daczero = seek(1024);

	/* Go halfway down and take an accurate sample */
	x = seek(512);
	oversample(x, &x1, &y1);

	/* Go halfway up and take an accurate sample */
	x = seek(768);
	oversample(x, &x2, &y2);

	/* Scale factor is 1/slope */
	scale = (x2 - x1) / (y2 - y1);
}

/* convert from (counts at ADC) to (counts at DAC) */
int32_t adc_toc(int16_t adc)
{
	int32_t r = ((float) adc) * scale;
	return r;
}