ShiftOut Clock Pin - Pin 12 only? [solved]

Projects Programming
1

Hi,

Done the ShiftOut tutorial, everything's fine, LEDs work as expected, but only when the Clock Pin is set to 12 (i.e. when the 74HC595 SH_CP Pin, which is IC Pin #11, is connected to Pin 12 on the Arduino). I've moved the Latch and Data pins to other outputs without problems, but whenever I set the Clock Pin to be other than the Arduino's 12 pin, I get funky behavior (LEDs flashing, not resetting properly etc). Why is that?

2

Perhaps post your code and circuit diagrams?

3

The code is long and rather irrelevant. I copy and paste the essential bit:

// Set the pin variables for addressing the 8-LED display
// Pin connected to ST_CP of 74HC595
int latchPin = 2;
// Pin connected to DS of 74HC595
int dataPin = 3;
// Pin connected to SH_CP of 74HC595
int clockPin = 12;

White wire: latchPin
Blue wire: dataPin
Yellow wire: clockPin

Actually after further testing, everything's fine as long as the Clock Wire (yellow) is connected to Arduino pin 10 to 13 (and the code updated accordingly). If I connect to pin 9 or any pin below that, the LEDs don't behave as expected. Is there some fundamental difference between pins 10-13 and 2-9?

Cam-1.jpg

4

Where's the part (code) where you do something with the shift register? The code you posted does not mean anything.... There might be a bug in your code somewhere.

5

Ischia:
Hi,

Done the ShiftOut tutorial, everything's fine, LEDs work as expected, but only when the Clock Pin is set to 12

Ischia:
The code is long and rather irrelevant. I copy and paste the essential bit:

The code on the linked page is not long and irrelevant. Are you saying that, using that, the LEDs don't work? Make up a test case, complete code, that demonstrates the problem, and post that.

Is there some fundamental difference between pins 10-13 and 2-9?

Pins 10 to 13 are used for hardware SPI, however the code on the linked page doesn't use that, and as for your code, well we can't see that.

6

I'm sorry for all this, it was of course stupid of me to assume the code was not to blame. I didn't want to paste it because it's very long, but it turns out I was sending servo commands to the HC595...

Thanks a lot for your help.