karelv
Small demo program I2C - PCF8574 showing that I2C class is not working on LPC4088
Revision 0:c3cff0038502, committed 2014-12-07
- Comitter:
- karelv
- Date:
- Sun Dec 07 13:54:14 2014 +0000
- Commit message:
- demo program for I2C
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 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);
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Sun Dec 07 13:54:14 2014 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/4fc01daae5a5 \ No newline at end of file