Fake 10-bit mode, using random number lookup for low bits.

Untested.  Need to test 16-bit mode (current compilation) first
then go back to 10-bit.

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@8027 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/calibrate.c

@@ -12,7 +12,7 @@ float g_scale;  /* delta(DAC) / delta(ADC) */
 /* Initialize.  Assume some relatively-safe scaling if no calibration is run */
 void calibrate_init(void)
 {
-	g_scale = 0.5;  /* 1 count at DAC means 4 counts at ADC */
+	g_scale = 0.5 * (DAC_RANGE / 65536);  /* 1 count at 16-bit DAC means 2 counts at ADC */
 }
 
 /* Given the current DAC and ADC values d1 and a1,
@@ -32,6 +32,10 @@ float calculate_scale(uint16_t d1, float a1, uint16_t d2, float a2)
 {
 	float scale;
 	float a = a2 - a1;
+	
+	/* Correct for known errors */
+	d1 = dac_get_actual(d1);
+	d2 = dac_get_actual(d2);
 
 	if (a < 0.1 && a > -0.1)
 		scale = 1.0;

firmware/calibrate.h

@@ -4,14 +4,14 @@
 #define ADC_CLAMP_MIN 256
 #define ADC_CLAMP_MAX 1792
 
-#define DAC_MIN 0
-#define DAC_MAX 65535
-
 #define OVERSAMPLE_COUNT 256
 
+#define DAC_MIN DAC_LOW
+#define DAC_MAX DAC_HIGH
+
 #define SEEK_MAX_STEPS 1000
-#define SEEK_FUZZ_ADC 10
-#define SEEK_FUZZ_DAC 5
+#define SEEK_FUZZ_ADC 100
+#define SEEK_FUZZ_DAC ((DAC_RANGE * 5) / 65536)
 
 #define CALIBRATE_ADC_ZERO 1024
 #define CALIBRATE_ADC_LOW 512

firmware/dac.c

@@ -30,20 +30,31 @@ void dac_init(void)
 	dac_write(0x0000);
 }
 
-/* Write raw 16-bit value to DAC:
-   0xFFFF 4.9998v
-   0x8000 0v
-   0x0000 -5v
+static const uint16_t dac_lookup[1024] = {
+  #include "lookup.inc"
+};
+
+/* Write raw 16-bit desired value to DAC:
+   DAC_HIGH 4.9998v
+   DAC_MID  0v
+   DAC_LOW -5v
  */
 void dac_write(uint16_t val)
 {
 	LATGbits.LATG9 = IO_LOW;
 	if (IO_HIGH == 1)
-		SPI2BUF = val;
+		SPI2BUF = __dac_actual(val);
 	else
-		SPI2BUF = ~val;
+		SPI2BUF = ~__dac_actual(val);
 	while (!SPI2STATbits.SPIRBF)
 		continue;
 	(void) SPI2BUF;
 	LATGbits.LATG9 = IO_HIGH;
 }
+
+uint16_t dac_get_actual(uint16_t val)
+{
+	return __dac_actual(val);
+}
+
+

firmware/dac.h

@@ -3,14 +3,38 @@
 
 #include "config.h"
 
+//#define FAKE_10_BIT
+
+#ifdef FAKE_10_BIT
+  /* fake compressed range with random lookup bits */
+  #define DAC_BITS 10
+  #define __dac_actual(x) (dac_lookup[(x)&1023])
+#else
+  /* normal range */
+  #define DAC_BITS 16
+  #define __dac_actual(x) (x)
+#endif
+
+#define DAC_LOW 0
+#define DAC_HIGH ((uint16_t)(((uint32_t)1 << DAC_BITS) - 1))
+#define DAC_MID ((uint16_t)((DAC_LOW + DAC_HIGH + (uint32_t)1) / 2))
+#define DAC_RANGE (DAC_HIGH - DAC_LOW + 1)
+
 /* Initialize DAC (AD5542) */
 void dac_init(void);
 
-/* Write raw 16-bit value to DAC:
-   0xFFFF 4.9998v
-   0x8000 0v
-   0x0000 -5v
+/* Write raw value to DAC:
+   DAC_HIGH 4.9998v
+   DAC_MID  0v
+   DAC_LOW  -5v
  */
 void dac_write(uint16_t val);
 
+/* From DAC value, get the expected actual output voltage:
+   0xffff 4.9998v
+   0x8000 0v
+   0x0000 -5v
+*/
+uint16_t dac_get_actual(uint16_t val);
+
 #endif

firmware/mode_debug.c

@@ -11,21 +11,25 @@
 #include "mode.h"
 #include "zoom.h"
 
-static uint16_t dac = 32768;
+static uint16_t dac = DAC_MID;
 
 void sweep(void)
 {
 	int32_t d;
 	int16_t a;	
 
+#define SWEEP ((DAC_HIGH - DAC_LOW) * (int32_t)2000 / 65535)
+
 	/* sweep range */
-	for (d = (int32_t)dac - 2000; d < (int32_t)dac + 2000; d++) {
-		if (d < 0x0000) {
-			uart1_put_string("0 0\r\n");
+	for (d = (int32_t)dac - SWEEP; d < (int32_t)dac + SWEEP; d++) {
+		if (d < DAC_LOW) {
+			uart1_put_dec(DAC_LOW);
+			uart1_put_string(" 0\r\n");
 			continue;
 		}
-		if (d > 0xffff) {
-			uart1_put_string("65535 0\r\n");
+		if (d > DAC_HIGH) {
+			uart1_put_dec(DAC_HIGH);
+			uart1_put_string(" 0\r\n");
 			continue;
 		}
 		dac_write(d);
@@ -50,6 +54,7 @@ void run_debug(void)
 	uart1_put_string("Zoom NILM Debug\r\n");
 
 	while (1) {
+		dac = dac & DAC_HIGH; // mask off invalid bits
 		dac_write(dac);
 		uart1_put_hex16(dac);
 		uart1_put(' ');
@@ -92,7 +97,7 @@ void run_debug(void)
 
 		// set DAC to midpoint
 		case '0':
-			dac = 32768;
+			dac = DAC_MID;
 			break;
 
 		// set DAC to specified hex value

firmware/mode_normal.c

@@ -84,12 +84,12 @@ void run_normal(void)
 
 	led_pattern(0b00110011);
 
-	/* Keep writing 32768 to the DAC for about 30 seconds after startup,
+	/* Keep writing zero to the DAC for about 30 seconds after startup,
 	   or until we receive a character on the UART */
 	while(uart1_can_get())
 		uart1_get();
 	for (i = 0; i < 1500; i++) {
-		dac_write(32768);
+		dac_write(DAC_MID);
 		if (uart1_can_get()) {
 			uart1_get();
 			break;

firmware/zoom.c

@@ -24,7 +24,7 @@ int main(void)
 
 	adcext_init();
 	dac_init();
-	dac_write(32768);
+	dac_write(DAC_MID);
 	adc_init();
 
 	/* Detect jumper from B8 to GND */

firmware/zoom.mcp

@@ -43,6 +43,7 @@ file_022=no
 file_023=no
 file_024=no
 file_025=no
+file_026=no
 [FILE_INFO]
 file_000=zoom.c
 file_001=config.c
@@ -69,7 +70,8 @@ file_021=mode.h
 file_022=zoom.h
 file_023=calibrate.h
 file_024=packet.h
-file_025=p33fj256gp710.gld
+file_025=lookup.inc
+file_026=p33fj256gp710.gld
 [SUITE_INFO]
 suite_guid={479DDE59-4D56-455E-855E-FFF59A3DB57E}
 suite_state=