Author Topic: How to determine spi pins?  (Read 616 times)

0 Members and 1 Guest are viewing this topic.

Offline sirtet

  • Contributor
  • Posts: 16
  • Country: ch
How to determine spi pins?
« on: January 28, 2018, 10:56:20 pm »
So, I have this Bluetooth module with a piggyback pcb on it, and on that pcb is an soc (csr8645), that has an spi port, but I can't tell if the spi pins are on the pcb, cause it's a bga chip.
There are 4 pins on the piggyback pcb (pins 12-15) that i guess are the spi ones, because
they go to test points on the main pcb bottom side.
But how to tell which is which?

Is there a  better approach to figure them out than trying lots of combinations,
Sending a command and probing for an answer?

Offline bitwelder

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: fi
Re: How to determine spi pins?
« Reply #1 on: January 30, 2018, 12:40:22 pm »
step 1. Plug a logic analyzer (or an oscilloscope that can also decode SPI) and observe?
step 2. Make guesses on the pins function and try to decode valid SPI messages?

Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo