lpcware

Start Condition Glitch with PCA9665

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by bubbzilla123 on Thu Jul 02 11:46:20 MST 2015
I'm having trouble setting up an I2C link between two boards. One has an EFM32 giant gecko microcontroller from Silicon Labs and the other (the master) is using a PCA9665 I2C controller from NXP.

I've recorded a 3 byte transaction using an (EFM32 and PCA9665) and (Arduino Uno and PCA9665) and attached some screen shots. The first row is an entire transaction and the next three are close ups of each piece of the transaction.

As I understand it, the EFM32 chip thinks there's a bad start condition and gives an NAK. Other microcontrollers (like the Arduino) don't have this problem...

[img=398x317]http://s27.postimg.org/sgcnwagoj/I2_C_Bad_Transaction.png[/img]

[img=398x193]http://s27.postimg.org/cgu0cqkmr/I2_C_Transaction.png[/img]

Does anybody have an idea to fix this?

Outcomes