Processor Expert Software中的主题 Re: Multiple chip selects on a spi port

Multiple chip selects on a spi port

barbercolman — Mon, 11 Mar 2013 13:13:17 GMT

I am using CW 10.3 and MQX 4.0. I am working with SPI0. I only see 1 chip select. I am using a MK20DN512VLK10 which shows more than 1 chip select available for SPI0. How do I enable / use a second chip select line?

Thanks

Re: Multiple chip selects on a spi port

DavidS — Mon, 11 Mar 2013 17:31:41 GMT

Hi Dale,

Please look at the MQXIOUG.pdf in the MQX4.0/docs/mqx path.

Section 9.6 Using the Driver elaborates on how to select the SPI module chip select when doing a fopen() operation:

Ex:

spifd = fopen("spi2:1", NULL); /* CS0 on bus spi2*/

Regards,

David

Re: Multiple chip selects on a spi port

barbercolman — Mon, 11 Mar 2013 17:43:21 GMT

I like your answer because it points to an open question I have. How much are we to use PE with MQX? I have a non PE application developed from the twr60K demo. I am porting the application to the k20 and because it appears that Freescale is moving to PE so started to work with PE. Where is the diving line, should I be setting up RS485 ports using PE or MQX?

Is there any good direction on what to use?

Re: Multiple chip selects on a spi port

DavidS — Mon, 11 Mar 2013 21:33:38 GMT

Hi Dale,

For our Kinetis L devices, they heavily reply on PE for baremetal and MQX Lite functionality.

The Kinetis K devices have used PE for clock configuration and quickly adding in drivers for on-chip peripherals. PE can also help when it comes to porting as the processor component can be changed out and/or helpful for changing packages.

The divide line is user specific. Some people like using PE much and other prefer using the MQX drivers and adding their own code. So no right or wrong answer.

Later this year Freescale will offer having the MQX Lite on the Kinetis K devices via PE and the PE will have some nice enhancements.

Regards,

David

Re: Multiple chip selects on a spi port

Monica — Thu, 21 Mar 2013 16:01:21 GMT

Dale,

did this help? We'd like to know! :smileywink:

Regards!