GPIO 26

[TheStaticTurtle]

I'm doing some work with the gpios and found that only 3 where listed.
For the one that doesn't know you cant access gpio 0 / 4 / 22 accessible on pin 17 / 6 / 18.
I found that gpio 26 which is accessible on pin 7 also works (at least as an input) is there a reason that it isn't listed on hackspire?
(Im using a nspire cx cas with ndless 4.2)

[critor]

Hi.

I did only test gpio in output mode, with a LED connected on each gpio pin of the dock connector.

The only ones which worked for me were :

• GPIO0 (pin 10 as labelled on the CX, pin 17 as described on hackspire)
• GPIO4 (pin 21 as labelled on the CX, pin 6 as described on hackspire)
• GPIO22 (pin 9 as labelled on the CX, pin 18 as described on hackspire)

Thanks for sharing your test results.

[TheStaticTurtle]

Yes after further testing gpio26 can only be used as an input. Do you know if there is more gpio accessible that is not on the dock connector?

[critor]

Thanks for clarifying.

Since we already have more adressable GPIO than pins available on the dock connector (after removing the GCC Rx Tx Vin GND pins), some GPIO may be accessible somewhere else.
Maybe on the top wifi connector, maybe internally on the PCB.
But in both cases, it's undocumented so far.

[TheStaticTurtle]

Found two more accessible gpios 16 and 15 on the top wifi connector don't know exactly where but they can be found on the connector but can be access by soldering on these two resistors:

GPIO are both pullups for the input mode and gpio 16 can be used as an output.
I don't know which one but during testing I use a very simple blink both gpio at the same time code and (HIGH-LOW-HIGH-LOW...) as expected gpio 16 blinked and when I exited the program gpio 15 turned on (weird since I wasn't accessible from ndless) and the OS think that a wifi module is plugged in and start searching for an ap

[TheStaticTurtle]

Btw is there an easy way to get the to top wifi connector instead of soldering?

[critor]

Great discovery, thanks for sharing.

Maybe by ordering a TI-Nspire CX wifi module and dismantling it :
https://www.ebay.com/sch/i.html?_from=R ... =0&_sop=15

[TheStaticTurtle]

Found two more GPIO 6 and GPIO 5 are available as test points near the top connector. As far as I've tested they can't be used as outputs and are inputs with very low pullups

[critor]

Thanks.

TP locations and maybe labels change with PCB revisions.
What's your calculator datestamp ?
It's the little 7-8 characters code engraved on the back at the right of the serial number.

[TheStaticTurtle]

It's P-0516X