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Data logging issue

Topic last updated 16 May 2011, by Levissz Levissz. 4 replies
Levissz Levissz
15 May 2011

Hey everyone!

I am having some problems to writing data to a microSD card through 4-wire SPI link. Checked the interrupt pin with scope and the issue is due to the fprintf line of the code.

Unfortunately I can't run the SPI clock too high, because a sensor has to be connected with an around 1m long cable to the mbed board.

So my question would be is it possible to run the two SPI links on a different speed? Not sure keep changing it in the code is a good solution?!

Possible to use sd mode to write to the sd card?

Thanks in advance!

Andy K
15 May 2011

The Mbed has two SPI interfaces. Why not use one for the SD and the other for your sensor?

Levissz Levissz
15 May 2011

I'am doing that just not sure if I can run them on different speed. Command for SPI speeds seems to be global for both interfaces or am I wrong?

Andy K
16 May 2011

No, they each have their own prescaler so can run at different speeds.

Levissz Levissz
16 May 2011

Thanks! Will give it a go!