CCS :: View topic - #use spi, selecting baud mode and slave select logic

FAQ

Forum Help

Official CCS Support

Profile Log in to check your private messages Log in

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to support@ccsinfo.com

#use spi, selecting baud mode and slave select logic

CCS Forum Index -> General CCS C Discussion

View previous topic :: View next topic

Author

Message

vsmguy

Joined: 13 Jan 2007
Posts: 91

#use spi, selecting baud mode and slave select logic

Posted: Fri Apr 19, 2013 1:28 pm

A SPI slave I am using (a FRAM device) requires me to hold the SS line low for multiple bytes in the same transaction (the first byte in a transaction is the command byte followed by context dependent bytes)

I would like to use a SPI clock frequency of 1MHz. The master is a PIC16F877A @20Mhz HS. The hardware SPI peripheral is unavailable.

My current soft SPI code looks like this:

Code:

#define FRAMSD_PIN_SELECT PIN_D0
#use spi(STREAM=SPI2, MASTER, bits=8, mode=3, DI=PIN_D3, DO=PIN_D2, CLK=PIN_D1)

1. What value of 'BAUD' should I select so that the SPI clock frequency is 1MHz? 1000000?

2. Also, is there a way to have the following hold the SS line low for multiple bytes in the same transaction or do I have to handle the ENABLE pin myself manually?

Code:

#use spi(STREAM=SPI2, MASTER, bits=8, mode=3, ENABLE=FRAMSD_PIN_SELECT, ENABLE_ACTIVE=0, DI=PIN_D3, DO=PIN_D2, CLK=PIN_D1, BAUD=<1MHz>)

Display posts from previous:

	CCS Forum Index -> General CCS C Discussion	All times are GMT - 6 Hours
Page 1 of 1

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum