BC127 SPI communication

I’m working on a board I designed that uses the BC127 module (not a dev kit). I want to use my own software but I’m having trouble communicating with the chip over the SPI. I’m wondering if there are any tricks to get the module talking SPI from its factory state. (I’m already pulling the SPI_*PCM line high.)

Some background: I’m not a confused beginner way over my head (I’m just a little over my head). I’ve made 3 or 4 previous versions of my board and they’ve eventually worked. I have a CSR SPI interface that I use to download my own firmware, which is based on CSR projects. One of the previous boards was giving me the same problem, no SPI communication, then I was finally able to connect (don’t know exactly what the magic was). Once I downloaded my software, I had no further problems communicating, indicating software settings made the difference.

I’m wondering if the PIOs need to be set a certain way or something like that. I have the PIOs attached to buttons and a switch that I’ll use for control.

This seems like talking to raw modules like this would be a common issue for companies making products with the BC127 modules.

I bought my current module from Digikey a few weeks ago. Thanks,


I built another board and saw the same SPI communication behavior as I’ve seen previously. With the original Sierra software in the device, in this case I could talk to the chip through SPI but it was slow and prone to errors. Once I overwrote the Sierra software with a standard CSR project the communication was much faster and worked better in general.

Anyone else see anything like this?