Oliver Broad
Control of MIC5821 octal driver using a SPI port (port1) and I/O pin (p21)
Revision 0:986765bd4f9e, committed 2012-07-08
- Comitter:
- oliverb
- Date:
- Sun Jul 08 18:51:51 2012 +0000
- Commit message:
- Tested
Changed in this revision
| main.cpp | Show annotated file Show diff for this revision Revisions of this file |
| mbed.bld | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Sun Jul 08 18:51:51 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);
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Sun Jul 08 18:51:51 2012 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/737756e0b479