Max GPIO pins usable?

Hardware Development
1

Hi Folks

I’m starting to design my first project and wanted to know
how many pins I could use for GPIO (both in and out).

(15-25,28) I want to use all 12 adc pins for analogue pot input.

(16,17,18,19) I want to use all 4 audio ins and outs.

(12,13) and I want to use 2 pins for a display I2C.

My daisy seeds wont arrive for a while, but I’m aware that usually these kind of MCU’s
usually have a few pins tied up with other hardware/functions .e.t.c.

My question is after I’ve used up the pins above - how many pins would be available for gpio in and out?

Looking at the board pin out

that leaves me with:

33,34,36,37,14,13,10,9,8,7,6,5,4,3,2,1 - 16 pins

I could those as charlieplexed ins and out ?

8 for input (8x7 = 56 CP’d switches)
8 for output (8x7 = 56 CP’d leds)

many thanks

Shabby

2

Or just use 74HC595(s) to provide huge numbers of outputs if you want them

1 Like
3

Hi MikeDB

Thanks for the info, but I’m fine with the led outputs, maybe for inputs to get rid of the cp diodes and even then I’m more about finding out the max gpio pins currently usable.

Shabby