Changes to fix the real-10-bit case.

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@9082 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/dac.c

@@ -43,22 +43,35 @@ void dac_write(uint16_t val)
 {
 	LATGbits.LATG9 = IO_LOW;
 	if (IO_HIGH == 1)
-		SPI2BUF = __dac_actual(val);
+		SPI2BUF = __dac_to_spi_cmd(val);
 	else
-		SPI2BUF = ~__dac_actual(val);
+		SPI2BUF = ~__dac_to_spi_cmd(val);
 	while (!SPI2STATbits.SPIRBF)
 		continue;
 	(void) SPI2BUF;
 	LATGbits.LATG9 = IO_HIGH;
 }
 
-uint16_t dac_get_actual(uint16_t val)
+/* Given a DAC command between DAC_LOW and DAC_HIGH,
+   get the actual expected output voltage as a 16-bit value, where:
+     0xffff = 4.9998v
+     0x8000 = 0v
+     0x0000 = -5v
+*/
+uint16_t dac_get_actual_16bit(uint16_t val)
 {
-	return __dac_actual(val);
+	return __dac_to_16bit_equiv(val);
 }
 
-/* Get actual output voltage from DAC_LOW to DAC_HIGH, as a float */
+/* Given a DAC command between DAC_LOW and DAC_HIGH,
+   get the actual expected output voltage as a FLOAT, where:
+     DAC_HIGH = 4.9998v
+     DAC_MID  = 0v
+     DAC_LOW  = -5v
+   Example: for 10-bit DAC, convert integer command 123 into
+   the more accurate 123.45 using known lower bits.
+*/
 float dac_get_actual_float(uint16_t val)
 {
-	return __dac_actual(val) * (DAC_RANGE / 65536.0);
+	return __dac_to_16bit_equiv(val) * (DAC_RANGE / 65536.0);
 }

firmware/dac.h

@@ -8,15 +8,18 @@
 #if DAC_TYPE == 0
   /* AD5542, normal 16-bit range */
   #define DAC_BITS 16
-  #define __dac_actual(x) (x)
+  #define __dac_to_spi_cmd(x) (x)
+  #define __dac_to_16bit_equiv(x) (x)
 #elif DAC_TYPE == 1
   /* AD5542, fake 10-bit range using random lower bits */
   #define DAC_BITS 10
-  #define __dac_actual(x) (dac_lookup[(x)&1023])
+  #define __dac_to_spi_cmd(x) (dac_lookup[(x)&1023])
+  #define __dac_to_16bit_equiv(x) (dac_lookup[(x)&1023])
 #elif DAC_TYPE == 2
   /* MAX504, true 10-bit DAC */
   #define DAC_BITS 10
-  #define __dac_actual(x) ((x) << 2)
+  #define __dac_to_spi_cmd(x) ((x) << 2)
+  #define __dac_to_16bit_equiv(x) ((x) << 6)
 #else
   #error Unknown DAC type
 #endif
@@ -36,14 +39,22 @@ void dac_init(void);
  */
 void dac_write(uint16_t val);
 
-/* From DAC value, get the expected actual output voltage:
-   0xffff 4.9998v
-   0x8000 0v
-   0x0000 -5v
+/* Given a DAC command between DAC_LOW and DAC_HIGH,
+   get the actual expected output voltage as a 16-bit value, where:
+     0xffff = 4.9998v
+     0x8000 = 0v
+     0x0000 = -5v
+*/
+uint16_t dac_get_actual_16bit(uint16_t val);
+
+/* Given a DAC command between DAC_LOW and DAC_HIGH,
+   get the actual expected output voltage as a FLOAT, where:
+     DAC_HIGH = 4.9998v
+     DAC_MID  = 0v
+     DAC_LOW  = -5v
+   Example: for 10-bit DAC, convert integer command 123 into
+   the more accurate 123.45 using known lower bits.
 */
-uint16_t dac_get_actual(uint16_t val);
-
-/* Get actual output voltage from DAC_LOW to DAC_HIGH, as a float */
 float dac_get_actual_float(uint16_t val);
 
 #endif

firmware/mode_debug.c

@@ -58,7 +58,7 @@ void run_debug(void)
 		dac_write(dac);
 		uart1_put_hex16(dac);
 		uart1_put(' ');
-		uart1_put_dec(dac_get_actual(dac));
+		uart1_put_dec(dac_get_actual_16bit(dac));
 		uart1_put(' ');
 		uart1_put(' ');
 		adc = adc_get();