TM1637 and Nano

Other Hardware Displays
1

Hi:

I've been using the TM1637 7-segment, 4-digit display in the Uno. Now I run the same sketch in a Nano but there is a problem: there is no persistence, I mean, after turning the segments on, they quickly turn off, so I can barely see the digits blinking.

This is the sketch, and as you can see, there is a 1-second delay between displays of numbers 1111...9999:

#include <TM1637Display.h>
// Module connection pins (Digital Pins)
#define CLK 5
#define DIO 6
TM1637Display display(CLK, DIO);
int d = 0;
void setup()
{
  display.setBrightness(7);
}
void loop() {
    while (d<=9999)
  {
    display.showNumberDec(d);
    delay(1000);
    d = d + 1111;
  }
  d = 1111;
}

It works fine in the Uno, the digits remain bright for one second until the next digit is displayed, but in the Nano they turn on only for a fraction of a second, then off until the next digit is displayed.

I thought there was a problem in the +5V pin with it not having enough power to turn the segments on, but if I remove the delay(1000) line, they are (almost) always.

Is there any compatibility issue here? Needles to say I tried different pins for CLK and DIO to no avail. And this Nano works fine in my other projects.

2

How are you powering the Nano? Sounds like not enough current, have you measured the supply voltage at the display?

3

avr_fred:
How are you powering the Nano? Sounds like not enough current, have you measured the supply voltage at the display?

I tried turning the segments on by displaying 8888 in a loop and they bright well. No problem with the power (and it's 5V at the display).

I solved the problem by altering the sketch. I count pulses in an interrupt to display rpm. There was a delay(1000) to display the reading every 1 second. Instead, I use a while() that exits after 1000 millis() and inside it I display the last reading, so the digits are always on.