topic Re: SPI communication, clocking data from a Slave device in 8-bit Microcontrollers

SPI communication, clocking data from a Slave device

DannyP — Thu, 03 May 2012 00:29:14 GMT

Hi,

I have been working on the SPI bus on the MC9S08. The writing to the slave works, whereas I am having a few problems with the reading part.

I see the command I send to the slave to go to read mode correctly sets the MISO line low and it is waiting for the SPI clock to spit out some data.

My question therefore is quite simple: Is it correct that to generate the SPI clock for every byte on I want to receive, I have to write a dummy byte into the SPID register and send it? I can't seem to find another way to generate the SPI clock.

Thanks in advance for any hints

Re: SPI communication, clocking data from a Slave device

rocco — Thu, 03 May 2012 03:46:10 GMT

Hi Danny,

Welcome to the forum.

. . . Is it correct that to generate the SPI clock for every byte on I want to receive, I have to write a dummy byte into the SPID register and send it?

Yes.

Re: SPI communication, clocking data from a Slave device

bigmac — Thu, 03 May 2012 09:56:40 GMT

Hello, and welcome to the forum.

Refer to one of the posts within this recent thread for a basic SPI master communications code example. It provides a single function that is capable of both send and receive SPI operations.

Regards,

Mac