Diff: main.cpp

Revision:

0:c3cff0038502

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Dec 07 13:54:14 2014 +0000
@@ -0,0 +1,44 @@
+#include "mbed.h"
+
+DigitalOut myled(LED4);
+I2C i2c(p9, p10);
+
+// Connections made:
+// SDA to pin9  of LPC4088 QSB
+// SCL to pin10 of LPC4088 QSB
+// on I2C bus is PCF8574 connected at sub-address 0 (0x40).
+// all supplied at 3.3V
+// no external pullup (Assuming that I2C-class is using 5K internal pullup)
+// 
+
+// this example does not work on my LPC4088 QSB.
+// mbed: 92:4fc01daae5a5
+//
+// note When I connect an external pulldown! (not pullup) of 10K on SDA & SCL it seems to work
+//      This is not logical.
+
+void 
+i2cIoWrite (char address, char data)
+{
+  i2c.start ();     
+  i2c.write (address);
+  i2c.write (data);
+  i2c.stop ();
+}
+
+
+int 
+main() 
+{
+  i2c.frequency (100000);
+
+  while (1)
+  {
+    myled = 1;
+    i2cIoWrite (0x40, 0x55);
+    wait(0.5);
+    myled = 0;    
+    i2cIoWrite (0x40, 0xAA);
+    wait (0.5);
+  }
+}