Denis Reilly

MCF5216 - Quick SPI Chip Select question

Discussion created by Denis Reilly on Jul 3, 2007
Latest reply on Jul 5, 2007 by Denis Reilly
I have a quick question for you all about chip selects for the ColdFire's QSPI block. (We are going to be using a 5216.)

We are in the process of designing a prototype board with four SPI peripherals (taking up all the available chip select lines), but we also want the ability to add peripherals at a later time. We want to avoid having to add hardware to decode the Chip Select lines, but we do have some spare GPIO available.

Is it valid to drive an SPI access with no Chip Select lines active? We would have to hook up the Chip Select line on our additional part to a GPIO line, of course, and drive it active outside of the QSPI block itself. But if an access like this is valid, we can hook up the parts we are using to the four chip select lines, and worry about expansion later (as long as all required signals are accesable on the board, of course).

Thanks in advance for your help!

Alban Edit: Please always mention part number in subject line.

Message Edited by Alban on 2007-07-09 04:52 PM