RE: Possible bug in TWI HW

Elena — Thu, 25 Sep 2014 14:37:04 GMT

Hi MatBB

I desisted about using the TWI peripheral and now I'm using the TWI SW to implement an I2C bus by using two GPIOs. Now it is working correctly.

Thanks for your help

RE: Possible bug in TWI HW

Matt Barr — Tue, 23 Sep 2014 13:50:18 GMT

I had trouble with TWI + softdevice and found this forum posting to be very useful:

devzone.nordicsemi.com/.../

In Stefan's answer you'll find a link to twi_hw_master_sd.c. I had trouble with link failures using twi_hw_master.c from the 6.0.0 SDK, these problems cleaned up after switching to the _sd version.

I do still see some apparent clock mis-behavior, but it appears as a shortened clock low time associated with a NAK:

The TWI master configured for 250 kHz operation, this shows an attempted access to a slave device that is not present. Fortunately the 1.1 us clock low time is well above the minimum clock low time for our slave devices and this isn't causing any problems.

If you are not already using it, you might try twi_hw_master_sd.c. I started a test yesterday that accesses a TWI slave every 100 ms under timer/scheduler control. TWI interface and BLE stack both survived the night.

Best Regards and Good Luck!

Matt