TWI on Custom PCB nrf51822

RE: TWI on Custom PCB nrf51822

Stian Røed Hafskjold — Tue, 23 Dec 2014 16:01:52 GMT

Okay! Good to hear:) I'll close the thread then.

RE: TWI on Custom PCB nrf51822

Michael Dietz — Tue, 23 Dec 2014 13:26:54 GMT

I actually got it to work using their internal pull-ups. It was a soldering error with my sensor. I am able to do 400 Khz i2c using no external pullups

RE: TWI on Custom PCB nrf51822

Stian Røed Hafskjold — Tue, 23 Dec 2014 11:18:33 GMT

Did you get it to work with external pull-ups?

RE: TWI on Custom PCB nrf51822

Matt Barr — Wed, 10 Dec 2014 21:12:33 GMT

It's worth a try. Our application was on the edge with internal pullups, worked intermittently at 100 kHz, didn't work at all at 250 kHz. (The first proto inadvertently omitted pullups so I tried this as a workaround.) Using a scope/analyzer to see what's really going on is definitely a good suggestion.

RE: TWI on Custom PCB nrf51822

Michael Dietz — Wed, 10 Dec 2014 18:17:08 GMT

No I'm relying on the internal pullup resistors. It works fine with the development board though thats what I'm confused about. I'll try out some 2.2k pull ups on a breadboard and see what happens though

RE: TWI on Custom PCB nrf51822

Matt Barr — Tue, 09 Dec 2014 21:18:42 GMT

When using your custom PCB do you have pull-up resistors on SDA and SCL? You want something in the 2.2k ballpark, the nRF51x22 internal pullups aren't sufficient for typical operating frequencies.

RE: TWI on Custom PCB nrf51822

Charles Manning — Tue, 09 Dec 2014 21:07:48 GMT

If you are communicating with other chips via I2C then something like a https://www.saleae.com/logic is very useful for development.

At the very minimum you want an oscilloscope so you can see what is happening.