Simple "zoom nilm" behavior & sending ADC/DAC data to the PC.

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@5936 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/adc.c

@@ -7,23 +7,34 @@
 */
 uint16_t adc_dmabuf[16] __attribute__((space(dma)));
 
+/* Stores the offset of the most recently written DMA sample */
+int adc_offset = 0;
+
 void (*adc_adc_callback)(void) = 0;
 void (*adc_dma_callback)(void) = 0;
 
-/* ADC1 interrupt after each sample (if enabled) */
+/* ADC1 interrupt after each sample */
 void __attribute__((__interrupt__,auto_psv)) _ADC1Interrupt(void)
 {       
+	static int next_adc_offset = 0;
+
+	adc_offset = next_adc_offset;
+
+	/* DMA0STA points to the next sample that will be written.
+	   Convert that into a buffer offset that we'll for next time */
+	next_adc_offset = (DMA0STA - __builtin_dmaoffset(adc_dmabuf)) >> 1;
+
+	IFS0bits.AD1IF = 0;
 	if (adc_adc_callback)
 		(*adc_adc_callback)();
-	IFS0bits.AD1IF = 0;
 }
 
 /* DMA0 interrupt after 16 samples */
 void __attribute__((__interrupt__,auto_psv)) _DMA0Interrupt(void)
 {
+	IFS0bits.DMA0IF = 0;
 	if (adc_dma_callback)
 		(*adc_dma_callback)();
-	IFS0bits.DMA0IF = 0;
 }
 
 /* Initialize ADC1 to constantly DMA AN0. */
@@ -72,12 +83,12 @@ void adc_init(void)
     DMA0CONbits.MODE = 0;           /* Continuous, no ping-pong */
     DMA0PAD = (int)&ADC1BUF0;       /* Get addresses from ADC1 */
     DMA0CNT = 15;                   /* 16 transfers before wraparound */
-    DMA0STA = __builtin_dmaoffset(&adc_dmabuf);
+    DMA0STA = __builtin_dmaoffset(adc_dmabuf);
     DMA0REQbits.IRQSEL = 13;        /* Triggered by ADC1 */
     IFS0bits.DMA0IF = 0;            
     IEC0bits.DMA0IE = 1;            /* DMA interrupt (every 16 samples) */
     DMA0CONbits.CHEN = 1;           /* enable this DMA channel */
 
     IFS0bits.AD1IF = 0;
-    IEC0bits.AD1IE = 0;				/* No ADC interrupt (every sample) */
+    IEC0bits.AD1IE = 1;				/* ADC interrupt (every sample) */
 }

firmware/adc.h

@@ -1,9 +1,12 @@
 #ifndef ADC_H
 #define ADC_H
 
-/* DMA region for the ADC */
+/* adc_dmabuf[x] contains 16 samples of channel AN0 */
 extern uint16_t adc_dmabuf[16];
 
+/* Stores the offset of the most recently written DMA sample */
+extern int adc_offset;
+
 /* Initialize internal ADC */
 void adc_init(void);
 

firmware/zoom.c

@@ -7,14 +7,56 @@
 #include <stdio.h>
 #include <math.h>
 
-int new_data = 0;
-uint16_t data;
+int send_data = 0;
+uint16_t send_adc, send_dac;
 
-void callback(void)
+/* Outside these thresholds, we step the DAC value */
+#define ADC_MIN 0x0100
+#define ADC_MAX 0x0e00
+
+/* Max/min DAC output value */
+#define DAC_MIN 0x0000
+#define DAC_MAX 0x0fff
+
+/* Shift the DAC value left this far when writing it out */
+#define DAC_SHIFT 4
+
+uint16_t dac_cmd = ((uint32_t)DAC_MAX + DAC_MIN) / 2;
+
+/* 128 KHz, after each ADC sample */
+void fast_callback(void)
+{
+	uint16_t v = adc_dmabuf[adc_offset];
+
+	if (v < ADC_MIN && dac_cmd < DAC_MAX)
+		dac_cmd ++;
+	if (v > ADC_MAX && dac_cmd > DAC_MIN)
+		dac_cmd --;
+
+	/* Write new value to DAC */
+	dac_write(dac_cmd << DAC_SHIFT);
+}
+
+/* 8 KHz, after DMA buffer filled */
+void slow_callback(void)
 {
 	/* Send most recent sample to PC */
-	data = adc_dmabuf[15];
-	new_data = 1;
+	send_adc = adc_dmabuf[adc_offset];
+	send_dac = dac_cmd;
+	send_data = 1;
+}
+
+void send_to_pc(void)
+{
+	/* Sent data format:
+  	   1Aaa aaaa  0aaa aaDd  0ddd dddd 0ddd dddd
+	   Aaaaaaaaaaaa = 12-bit ADC value
+       Dddddddddddddddd = 16-bit DAC command
+	*/
+	uart1_put(0x80 | ((send_adc & 0x0FE0) >> 5));
+	uart1_put(((send_adc & 0x001F) << 2) | ((send_dac & 0xC000) >> 14));
+	uart1_put((send_dac & 0x3F80) >> 7);
+	uart1_put((send_dac & 0x007F));
 }
 
 int main(void)
@@ -24,15 +66,13 @@ int main(void)
 	adcext_init();
 	dac_init();
 	adc_init();
-	adc_dma_callback = callback;
+	adc_adc_callback = fast_callback;
+	adc_dma_callback = slow_callback;
 
 	while(1) {
-		if (new_data) {
-			uart1_put_hex16(data);
-			uart1_crlf();
-			new_data = 0;
+		if (send_data) {
+			send_to_pc();
+			send_data = 0;
 		}
 	}
-
-	for(;;) continue;
 }