Fix DAC stuff slightly

Update code to test bipolar dac

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@6027 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/dac.c

@@ -30,7 +30,11 @@ void dac_init(void)
 	dac_write(0x0000);
 }
 
-/* Write raw 16-bit value to DAC */
+/* Write raw 16-bit value to DAC:
+   0xFFFF 4.9998v
+   0x8000 0v
+   0x0000 -5v
+ */
 void dac_write(uint16_t val)
 {
 	LATGbits.LATG9 = 0;

firmware/dac.h

@@ -3,10 +3,14 @@
 
 #include "config.h"
 
-/* Initialize ADC */
+/* Initialize DAC (AD5542) */
 void dac_init(void);
 
-/* Write raw 16-bit value to DAC */
+/* Write raw 16-bit value to DAC:
+   0xFFFF 4.9998v
+   0x8000 0v
+   0x0000 -5v
+ */
 void dac_write(uint16_t val);
 
 #endif

firmware/zoom.c

@@ -30,8 +30,10 @@ void fast_callback(void)
 
 	if (v < ADC_MIN && dac_cmd < DAC_MAX)
 		dac_cmd ++;
-	if (v > ADC_MAX && dac_cmd > DAC_MIN)
+	else if (v > ADC_MAX && dac_cmd > DAC_MIN)
 		dac_cmd --;
+	else
+		return; /* No new command */
 
 	/* Write new value to DAC */
 	dac_write(dac_cmd << DAC_SHIFT);
@@ -66,9 +68,19 @@ int main(void)
 	adcext_init();
 	dac_init();
 	adc_init();
-	adc_adc_callback = fast_callback;
-	adc_dma_callback = slow_callback;
+//	adc_adc_callback = fast_callback;
+//	adc_dma_callback = slow_callback;
 
+	{ 
+		int16_t i = 0;
+		while(1) {
+			i++;
+			dac_write(i);
+			uart1_put_hex16(i);
+			uart1_crlf();
+		}
+	}
+			
 	while(1) {
 		if (send_data) {
 			send_to_pc();