Diff: main.cpp

Revision:

0:177a872748b8

Child:

1:46c26c1de51f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Jul 08 16:49:43 2012 +0000
@@ -0,0 +1,32 @@
+#include "mbed.h"
+// Use SPI port to write an 8 bit pattern to MIC5821 open collector driver device.
+// MBED led1 lights if pattern read back from MIC5821 matches pattern written
+// Ordinarily the device would be write-only but loopback may be usefull in testing.
+// Cascade output is NOT tristate. Strobe is NOT a CS/SS signal, needs a pulse.
+//
+// Note that the MIC has a speed limit, 3.3MHz at 5v, mine works OK at 1MHz at 3.3v
+// Also input has CMOS thresholds so it may not recognise MBED logic HI when powered
+// from 5v so power it from Vout.
+//
+// Data is clocked in on rising edges so SPI 0,0 or SPI 1,1. 
+
+SPI spi(p5, p6, p7); // mosi, miso, sclk
+
+DigitalOut strobe(p21);
+DigitalOut led(LED1);
+
+int main() {
+    spi.format(8,0);
+    spi.frequency(1000000);
+    char leds,prev;
+    leds=0;
+    while(1) {
+        prev=spi.write(leds)+1;
+        led=(prev == leds);
+        leds++;
+        strobe=1;
+        wait_us(1);
+        strobe=0;
+        wait(0.5);
+    }
+}