[riot-notifications] [RIOT-OS/RIOT] SPI MISO of SPI0 should be pulled in FRDM-KW41Z (#11460)

Thomas Stilwell notifications at github.com
Tue Apr 30 16:24:49 CEST 2019

You're right. Currently the default configuration doesn't enable pullups for spi miso and also uart rx.

The bit definition for turning on the pullup is `GPIO_IN_PU`. You can add it to periph_conf.h like so:

`.pcr      = GPIO_AF_2 | GPIO_IN_PU,`

This will enable the pullup on all spi pins, which should be harmless but of course there's no need for pullups on the driven pins.

Alternately, you can add it to spi.c like so:

`gpio_init_port(spi_config[bus].pin_miso, spi_config[bus].pcr | GPIO_IN_PU);`

This way the pullup is only enabled on miso.

Probably we should change all the board configurations to enable pullups where appropriate. It looks like many boards have no pullups by default, which is fine for development, but a floating uart rx pin will definitely cause intermittent boot failures in the field.

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