karelv
/
i2c_lpc4088
Small demo program I2C - PCF8574 showing that I2C class is not working on LPC4088
main.cpp
- Committer:
- karelv
- Date:
- 2014-12-07
- Revision:
- 0:c3cff0038502
File content as of revision 0:c3cff0038502:
#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); } }