Working with TX output and SparkFun 7-Seg Serial Display [SOLVED - wiring issue]

I recently purchased a serial 7-seg display from SparkFun.

The code I’m working with is below:

int cycles = 0;

void setup() {
    pinMode(TX, OUTPUT);

void loop() {
    char tempString[10];
    sprintf(tempString, "%4d", cycles);

It’s probably extremely obvious what I’m doing wrong, but I for the life of me can’t figure this out.

I have my VIN connected to the 7-Seg’s VCC, my GND connected to the 7-Seg’s GND, and my TX connected to the 7-Seg’s RX.

In the Arduino world, there is a big difference between Serial1.write() which sends a single character and Serial1.print() which sends the whole string. I think you want Serial1.print(tempString); instead of write().

Can you try changing that?

I did, and it still doesn’t make a difference. The 7-seg display is still showing all zeroes.

OK have you tried something like the Sparkfun example, skipping all the other stuff for now?


It still doesn’t do anything. Just all zeroes on the display.

Got it working, my pins weren’t making a secure connection.

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