Diff: main.cpp

Revision:

0:723ec6d615c7

Child:

1:77d25d0f67d6

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Feb 22 17:25:26 2011 +0000
@@ -0,0 +1,89 @@
+/*
+ * MCP4822A DAC array library demonstration program.
+ *
+ * Copyright (c) 2011 Steven Beard, UK Astronomy Technology Centre.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "mbed.h"
+#include "MCP4822A.h"
+
+/*
+ * In this example there are 4 DAC chips daisy-chained on the SPI bus,
+ * which together provide 8 channels.
+ */
+const int ndacs = 4;
+const int nchans = ndacs * 2;
+
+/*
+ * The following mbed pins are used:
+ *
+ * p11 - SPI mosi
+ * p13 - SPI sclk
+ * p14, p15, p16, p17 - CS pins, each connected to a separate DAC.
+ * p21 - LDAC pin, connected to all DAC chips.
+ */
+PinName cspins[] = {(p14),(p15),(p16),(p17)};
+MCP4822A MCP(ndacs, p11, p13, cspins, p21);    // MOSI, SCLK, nCS-list, nLdac
+
+int main() {
+    int i, buffer;
+
+    printf("\r\n\r\nSetting SPI clock frequency to 10 MHz.\r\n");
+    MCP.frequency(10000000);
+    
+    // Begin by setting all the DACs to 1000 millivolts at gain 2.
+    printf("Loading all channels with 1000mV at gain 2...\r\n");
+    MCP.latch_disable();
+    for (i=0; i<ndacs; i++) {
+        MCP.writeA2(i, 1000);
+        MCP.writeB2(i, 1000);
+    }
+    wait(4);
+    printf("Latching now.\n");
+    MCP.latch_enable();
+    wait(4);
+
+    // Initialise an array of test voltages (in mV).
+    int test_voltages[nchans];
+    for (i=0; i<nchans; i++) {
+        test_voltages[i] = i * 500;
+    }
+
+    while (1) {
+
+        // Write the array of test voltages to the DACs
+        // (at gain 2 with automatic latching).
+        printf("Writing: ");
+        for (i=0; i<nchans; i++) {
+            printf("%d ", test_voltages[i]);
+        }
+        printf("\r\n");
+        MCP.write(nchans, test_voltages, 2, 1);
+        wait(4);
+
+        //Move the values in the array along one place.
+        buffer = test_voltages[0];
+        for (i=0; i<(nchans-1); i++) {
+            test_voltages[i] = test_voltages[i+1];
+        }
+        test_voltages[nchans-1] = buffer;
+    }
+}
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