add DAC magic for AD5542.

git-svn-id: https://bucket.mit.edu/svn/nilm/zoom@5476 ddd99763-3ecb-0310-9145-efcb8ce7c51f

firmware/dac.c

@@ -1,15 +1,42 @@
 #include "config.h"
 #include "dac.h"
 
+/* Initialize DAC */
 void dac_init(void)
 {
-	/* data bus on port D */
-	TRISD = 0;
-	TRISEbits.TRISE0 = 0;
-	// TODO
+	/* SPI2 */
+	IEC2bits.SPI2IE = 0;
+
+	SPI2CON1bits.DISSCK = 0;
+	SPI2CON1bits.DISSDO = 0;
+	SPI2CON1bits.MODE16 = 1;
+	SPI2CON1bits.SMP = 0;
+	SPI2CON1bits.CKE = 0;
+	SPI2CON1bits.SSEN = 0;
+	SPI2CON1bits.CKP = 1;	
+	SPI2CON1bits.MSTEN = 1;
+	SPI2CON1bits.SPRE = 4;
+	SPI2CON1bits.PPRE = 3;
+
+	/* There's no framed mode that does the normal
+       "chip select" behavior, so control /SS2 manually */
+	SPI2CON2bits.FRMEN = 0;
+	LATGbits.LATG9 = 1;
+	TRISGbits.TRISG9 = 0;
+
+	SPI2STATbits.SPISIDL = 0;
+	SPI2STATbits.SPIEN = 1;
+
+	dac_write(0x0000);
 }
 
+/* Write raw 16-bit value to DAC */
 void dac_write(uint16_t val)
 {
-	// TODO
+	LATGbits.LATG9 = 0;
+	SPI2BUF = val;
+	while (!SPI2STATbits.SPIRBF)
+		continue;
+	(void) SPI2BUF;
+	LATGbits.LATG9 = 1;
 }

firmware/dac.h

@@ -3,7 +3,10 @@
 
 #include "config.h"
 
+/* Initialize ADC */
 void dac_init(void);
+
+/* Write raw 16-bit value to DAC */
 void dac_write(uint16_t val);
 
 #endif

firmware/zoom.c

@@ -1,19 +1,22 @@
 #include "config.h"
 #include "adc.h"
+#include "dac.h"
 #include "uart.h"
 #include <stdio.h>
 
 int main(void)
 {
 	uint32_t v;
+	char ch;
 	config_init();
 	uart1_init(115200);
 	
 	adc_init();
-	uart1_put_string("ADC test\r\n");
+	dac_init();
+	uart1_put_string("ADC/DAC test\r\n");
 
 	for(;;) {
-		switch(uart1_get()) {
+		switch((ch = uart1_get())) {
 			case 'r':
 				uart1_put_string("read");
 				v = adc_read();
@@ -33,8 +36,23 @@ int main(void)
 					uart1_put('.');
 				uart1_put_string("done\r\n");
 				break;
+			case '1'...'9':
+				v = (ch - '1') * 0x2000L;
+				if (v > 65535) v = 65535;
+				uart1_put_string("write 0x");
+				uart1_put_hex16(v);
+				uart1_put_string("\r\n");
+				dac_write(v);
+				break;
+			case 't':
+				for (v = 0; v < 8; v++) {
+					dac_write(0x0000);
+					dac_write(0xFFFF);
+				}
+				break;				
 			default:
-				uart1_put_string("choose: Read Convert\r\n");
+				uart1_put_string("ADC: Read Convert\r\n");
+				uart1_put_string("DAC: 123456789 Toggle\r\n");
 				break;
 		}
 	}