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mBuino pullup resistors for spi?


#1

Does the mBuino have pullup resistors enabled for the MOSI and MISO pins?

I’m getting ready to test the my SD card with the mBuino.

Thanks

Eric


#2

@ DaddyOh - I am not near my computer. You can download eagle files and check schematics.

http://developer.mbed.org/platforms/Outrageous-Circuits-mBuino/


#3

@ DaddyOh - The SPI channel that we expose to the user does not have external pull-ups on the lines.

As for if the “firmware” has pull-ups enabled, I am not sure. We use the standard mbed SPI controller and I am not sure if the lines have the pull-ups enabled. You could probably manually add the pull-ups through register access if the SDK does not enable them.


#4

I don’t think the SPI library uses the internal pullups, they may not be the correct value for all situations and so forcing them on for all SPI wouldn’t be a good idea.

The standard mBed workaround is to define the pins as digital inputs with the pullup enabled and then define the SPI bus.
e.g.

DigitalIn dummy1(MISO,PullUp);
DigitalIn dummy2(MOSI,PullUp);
SPI spiBus(MOSI,MISO);

Alternatively you can always change the CPU registers directly. More efficient but also more painful.


#5

AndyA

thanks

I will try this
DigitalIn dummy1(MISO,PullUp);
DigitalIn dummy2(MOSI,PullUp);
SPI spiBus(MOSI,MISO);