When i started using the BIGTREETECH CB1* on the BIGTREETECH E3EZ* i quickly got into the trouble of mapping all the pin descriptions to gpio numbers. Luckily i’m not alone and i found a solution here .

The BIGTREETECH CB1 uses a custom IO pinout for the pins which consists of PA, PB….PG and a number. To calculate a GPIO Number, you need to use the following formula:

[(PG - PA)*32] + {Pin Number}
Where PA = 1, PB =2….so PG = 7

So if you want to calculate PG19, then it would be ((7-1)*32) + 19 = 211 = GPIO211. Potentially also this lookup table  might help.

The pins of the 40-pin connector are listed here already - maybe that helps to quickly get the right numbers ;-)