zoom/firmware/mode_normal.c

#include "config.h"
#include "adc.h"
#include "adcext.h"
#include "dac.h"
#include "uart.h"
#include "timer.h"
#include <stdio.h>
#include <math.h>
#include "scaling.h"
#include "util.h"
#include "mode.h"
#include "zoom.h"

int send_data = 0;
uint16_t send_adc;
uint16_t send_dac;
int possible_overflow = 0;

float dac_current;

#define TIMER_RATE 8000   /* how often to read the ADC and update DAC */
#define PC_RATE 8000      /* how often to send data to the PC */

/* Run mode */
void TISR_HANDLER(5)
{
	static int count = 0;
	static uint16_t dac_cmd;
	int16_t v;
	float i;

	/* toggle A9 every time an interrupt occurs */
	LATAbits.LATA9 = 1;
	timer_clear_txif(5);
	
	/* Get most recent sample from 12-bit ADC. */
	v = adc_get();

	if (v < 0 || v >= 2047)
		possible_overflow = 1;

	/* Send data to PC at 1 Hz */
	if (++count >= (TIMER_RATE / PC_RATE)) {
		count = 0;
		
		/* Send most recent sample and old DAC value */
		send_adc = v;
		send_dac = dac_cmd;
		send_data = 1;
	}

	/* Convert ADC value to current */
	i = adc12_to_current(v);

#if 0
	/* Adjust DAC to null this current to 0 */
	dac_current -= i;
#else
	/* If this current exceeds +-1A, cancel it out at the DAC */
	if (i < -1.0 || i > 1.0)
		dac_current -= i;
#endif

	if (dac_current < dac_current_min)
		dac_current = dac_current_min;
	if (dac_current > dac_current_max)
		dac_current = dac_current_max;

	/* Now send it out */
	dac_cmd = current_to_dac(dac_current);
	dac_write(dac_cmd);

	LATAbits.LATA9 = 0;
}

void send_to_pc(uint16_t adc, uint16_t dac)
{
	/* Sent data format:
  	   1Aaa aaaa  0aaa aaDd  0ddd dddd 0ddd dddd
	   Aaaaaaaaaaaa = 12-bit ADC value (2s compliment signed)
       Dddddddddddddddd = 16-bit DAC command (unsigned)
	*/	
	uart1_put(0x80 | ((adc & 0x0FE0) >> 5));
	uart1_put(((adc & 0x001F) << 2) | ((dac & 0xC000) >> 14));
	uart1_put((dac & 0x3F80) >> 7);
	uart1_put((dac & 0x007F));
}

void run_normal(void)
{
	uart1_init(500000);
	led_on();

	/* Assume startup current is 0 */
	dac_current = 0.0;
	dac_write(current_to_dac(dac_current));
	msleep(100);
	degauss();

	timer_setup_16bit(5, TIMER_RATE, 1);
	timer_set_priority(5, 6);

	while(1) {
		if (send_data) {
			/* There's data to send.  Disable the ISR briefly
			   while we grab it */
			uint16_t a, d;
			disable_int({
				if (possible_overflow) {
					/* Mark a possible overflow in the output
					   by setting ADC to an unlikely value */
					possible_overflow = 0;
					a = 0x0800;
				} else {
					a = send_adc;
				}
				d = send_dac;
				send_data = 0;
			});
			send_to_pc(a, d);
		}
	}
}