Which RPI GPIO pins are inaccesible?

Question

I'm using 10.0.10240 with a Raspberry PI 2 and am experiencing COM error exceptions when I try to open GPIO 17, 19, 20, and 21. Other GPIO pins appear to work fine.

I found this website [http://www.pridopia.co.uk/pi-edu-v02-win10.html] saying "Microsoft reserved GPIO 19,20,21,17 as SPI1 signal so we can't use these pins as normal GPIO signal". This matches what I'm experiencing. I can't find anything direct from Microsoft stating these pins are disabled however.

This page from Microsoft says that all GPIO pins are available: https://ms-iot.github.io/content/en-US/win10/samples/PinMappingsRPi2.htm, and this one says all except GPIO 1 and 2 are available: http://ms-iot.github.io/content/en-US/win10/ReleaseNotes.htm

Where can I find accurate and up to date information about features Microsoft has inexplicably taken away from the Raspberry PI? I keep running into issues like this.

Answer 1

https://ms-iot.github.io/content/en-US/win10/samples/PinMappingsRPi2.htm

• 17x - GPIO pins
• 1x - SPI bus
• 1x - I2C bus
• 2x - 5V power pins
• 2x - 3.3V power pins
• 8x - Ground pins

but even that is out of date as Serial Rx/Tx are available now in 10556.

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riclh

Answer 2

With software version 10.0.14342.1000 it is GPIO 0-1-14-15 that is not accessible. GPIO 0-1 are reserved for I2C 0 and GPIO 14-15 are configured as UART. Hopefully Microsoft will give back these GPIO to the user in a future release.

With earlier versions up to 11 GPIO was stolen by  Microsoft. I have never used 10240 but in the latest release still most of the pins that were assigned to SPI functions were inaccessible as GPIO for Input/Output. You have to go with the "Windows 10 IoT Core Insider Previev" to have the latest GPIO access. The 14342 also works with Raspberry Pi 3. Be aware of that boot up status of pin 9-10-11 is Low.  Latest Microsoft Pin mapping show these pins boot up High.