Niklas Forsgren

Sending 3 bytes over SPI without /SS getting high

Discussion created by Niklas Forsgren on Jun 12, 2006
Latest reply on Jun 12, 2006 by Niklas Forsgren
As newbie to programming and S12 I have what might be a silly question.

I am going to use S12 to send 3 bytes of data to 3 daisy chained shift regs. What I want is this: when I initiate the transfer I would like /SS to go low, thereby selecting my slave device. Then I send 3 bytes and after that transfer is done, I would like /SS pin to go high and latch data from shiftregs to their output.

The function I am looking for is exactly what I understand is possible to do if the transmission were only one byte.

One solution to this would be to disable the /SS pin from SPI and use it as GPIO. In that way I can have the function I want but it needs to be controlled by SW.

Is it possible to send 3 bytes over SPI with /SS low during the whole transmission?

Greatful for all responses!