Kinetis Software Development KitのトピックRe: How do you change SPI speed after it's set?

How do you change SPI speed after it's set?

myke_predko — Mon, 25 Jan 2016 17:10:48 GMT

Hey gang,

I am making progress with my Kinetis/KSDK 1.3/PE 3.0.2 SD Card software for SPI on a FRDM-K22F Board (going to a custom K22 board in the future).

One question, how do I increase the SPI speed after I set it originally using the DSPI_DRV_MasterConfigureBus (I'm using Interrupt based SPI right now) to 375kbps? After the card is initialized, I should be able to run it at a faster data rate.

I want to run at at least 10 MHz.

I'm using a K22F and when I look at the SPI clocking options in PE, I see that the maximum (using the default Clock cfg.4) is 2.4 MHz although that's "From" and "To" says 12 MHz. Can anybody explain this?

I am hoping to publish my software here in a few days.

Thanx,

myke

Re: How do you change SPI speed after it's set?

Alice_Yang — Tue, 26 Jan 2016 02:16:06 GMT

Hello myke,

I check on my side , the clock rate of spi can configured to 10MHZ, and could you please show your project , and how about your

bus clock of mcu, the clock source of SPI is the bus clock .

And i recommend you do not change the speed when run the project , it maybe cause unpredictable problems .

Hope it helps

Alice

Re: How do you change SPI speed after it's set?

myke_predko — Fri, 29 Jan 2016 06:18:13 GMT

Hi Alice,

Thank you for the reply - to change the speed in the application, I found that re-running "DSPI_DRV_MasterConfigureBus" when I wanted to change the speed worked for me.

By doing this on a FRDM-K22F, I found that the maximum speed that I seemed to be able to change the stock hardware to is 4.8 Mbps. I haven't pushed it to 10 Mbps or looked at changing the internal clocking information.

myke

Re: How do you change SPI speed after it's set?

Alice_Yang — Mon, 01 Feb 2016 08:57:18 GMT

Hello myke,

So your problem have been solved ?

Alice

Re: How do you change SPI speed after it's set?

myke_predko — Sun, 07 Feb 2016 04:13:49 GMT

Hi Alice,

Yes it has, I am calling the DSPI_DRV_MasterConfigureBus API to change the speed before initializing the SD Card and then increase the speed after initializing the card.

myke