Pro Mini Pins A6, A7 digitalWrite not functioning as expected.?

Hardware
1

Hello, I am trying to piggyback a 128x64 OLED onto a Pro Mini clone using pins A4-A7 where A6 and A7 will power the OLED to make assembly easy. I confirmed that the OLED will not exceed max recommended current for A6 and A7. I added the lines that I thought would do the job in my sketch but the pins are not reading 5vdc (reading about 1vdc). I am running a Pro Mini 5v 16Mhz powered via RAW. I think the sketch lines are correct so I am posting this in hardware as I suspect it is more of a Pro Mini issue? I have been working on this for hours and would welcome any suggestions. Thanks

void setup() {

    //Power to OLED
    pinMode(A6, OUTPUT); 
    pinMode(A7, OUTPUT);
    digitalWrite(A6, HIGH);
    digitalWrite(A7, LOW);
2

Have you considered the possibility that A6 and A7 are analogue in only, as they are on the Nano ?

2 Likes
3

Most of the analog pins can also be used as digital pins with the following numbering: from A0 == Digital pin 14 to A5 == Digital pin 19.
HOWEVER: Analog pins 6 and 7 (present on the Mini) cannot be used as digital pins. They are only analog pins.
A6 and A7 are only inputs available to the mux in front of the ADC.
There is no digital hardware behind the pins.
Since the pull up is part of the digital latch, those two pins dont have pull ups (nor do they work as digital inputs!!!)
Keep in mind that pinMode() has no effect on analog pins

1 Like
4

Hi Bob, I have considered that, I looked at the 328P chip pinout and it looks like it can be used digital but maybe I am wrong.

5

Thanks for confirming Bobs thought too hml. I will skip the piggyback and just spend the extra time. Thank you both for confirming this.

6

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.