untested: support for AD9834 + AD5620

1 files changed, 89 insertions, 0 deletions

diff --git a/dds.c b/dds.c
new file mode 100644
index 0000000..8002d78
--- /dev/null
+++ b/dds.c
@@ -0,0 +1,89 @@
+#include <stdbool.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "dds.h"
+
+#define IIODEVICEPATH "/sys/bus/iio/devices/iio:device"
+#define DACIIODEVICE "0"
+#define DDSIIODEVICE "1"
+
+#define DDSFREQNODE "dds0_freq0"
+#define DDSOUTPUTENABLENODE "dds0_out_enable"
+#define DDSSQOUTPUTENABLENODE "dds0_out1_enable"
+#define DDSWAVETYPENODE "dds0_out0_wavetype"
+#define DDSWAVETYPESINE "sine\n"
+#define DDSWAVETYPETRI "triangle\n"
+
+#define DACSCALENODE "out_voltage_scale"
+#define DACOUTPUTNODE "out_voltage0_raw"
+
+#define ENABLE "1\n"
+#define DISABLE "0\n"
+
+void dds_setamplitude(float millivolts)
+{
+	int scalefd = open(IIODEVICEPATH""DACIIODEVICE"/"DACSCALENODE, O_RDONLY);
+	int outputfd = open(IIODEVICEPATH""DACIIODEVICE"/"DACOUTPUTNODE, O_WRONLY);
+
+	if (outputfd < 0 || scalefd < 0) {
+		printf("Couldn't open one or more of the control nodes for the dac\n");
+	}
+
+	// read the scale value and turn it into a float
+	float scale = 0;
+	char scalebuff[64];
+
+	if (read(scalefd, scalebuff, sizeof(scalebuff))) {
+		sscanf(scalebuff, "%f\n", &scale);
+	}
+
+	if (scale == 0) {
+		printf("couldn't read scale or scale is invalid\n");
+		return;
+	}
+
+	// create a buffer with the scaled millivolt value and write it
+	char outputbuff[64];
+	int outputchars = snprintf(outputbuff, sizeof(outputbuff), "%d\n", (int) (millivolts / scale));
+	write(outputfd, outputbuff, outputchars);
+
+	close(scalefd);
+	close(outputfd);
+}
+
+void dds_setupwave(int frequency, bool squarewaveoutput, bool triangle)
+{
+	int wavetypefd = open(IIODEVICEPATH""DDSIIODEVICE"/"DDSWAVETYPENODE, O_WRONLY);
+	int outputenablefd = open(IIODEVICEPATH""DDSIIODEVICE"/"DDSOUTPUTENABLENODE, O_WRONLY);
+	int sqwaveenablefd = open(IIODEVICEPATH""DDSIIODEVICE"/"DDSSQOUTPUTENABLENODE, O_WRONLY);
+	int freqfd = open(IIODEVICEPATH""DDSIIODEVICE"/"DDSFREQNODE, O_WRONLY);
+
+	if (wavetypefd < 0 || outputenablefd < 0 || sqwaveenablefd < 0 || freqfd < 0) {
+		printf("Couldn't open one or more of the control nodes for the dds\n");
+		return;
+	}
+
+	if (triangle) {
+		// squarewave output on the signbit out pin can't be selected at the same time as triangle wave
+		write(sqwaveenablefd, DISABLE, sizeof(DISABLE));
+		write(wavetypefd, DDSWAVETYPETRI, sizeof(DDSWAVETYPETRI));
+	} else {
+		// enable/disable the square wave ouput and reset the wavetype
+		write(sqwaveenablefd, squarewaveoutput ? ENABLE : DISABLE, squarewaveoutput ? sizeof(ENABLE) : sizeof(DISABLE));
+		write(wavetypefd, DDSWAVETYPESINE, sizeof(DDSWAVETYPESINE));
+	}
+
+	// generate a buffer with the frequency and set it
+	char freqbuff[64];
+	int freqchars = snprintf(freqbuff, sizeof(freqbuff), "%d\n", frequency);
+	write(freqfd, freqbuff, freqchars);
+
+	write(outputenablefd, ENABLE, sizeof(ENABLE));
+
+	close(sqwaveenablefd);
+	close(wavetypefd);
+	close(freqfd);
+	close(outputenablefd);
+}