4-Digit 7-Segment Display Help

[mcscott]

I'm running a Adafruit 0.56" 4-Digit 7-Segment Display w/I2C Backpack - Red, and I have it working but I'm wondering if there's a way in the program to make it display a zero, when the value that I'm printing to it is zero. Right now it only displays the value when it is non-zero.

Thanks everyone

[Franklin97355]

That's in the code. There will be a section that blanks leading zeros and you just need to change or disable that. If you post your code perhaps we can help.

[mcscott]

Code: Select all

// CONSTANTS
const int ledPin = 10; // led connected to digital pin 10
const int sensor0 = A0; // the sensor is connected to analog pin 0
const int thresholdMin = 25; // minimum threshold value to decide when the detected impacts or not
const int thresholdMax = 100; // maximum threshold value to decide when the detected impacts or not
const int deltaTmax = 400; // maximum impact duration to discrimate impacts (us)
const int deltaTmin = 100; // minimum impact duration to discrimate impacts (us)
const int ledOn = 5; // LED on delay when impact is detected (ms)

// VARIBALES
int ledState = LOW; // variable used to store the last LED status, to toggle the light
unsigned long deltaT; // variable used to store time duration of impact
int impactCount = 0; // varible used to count impacts
unsigned long tStart; // variable to log start time of impact (us)
unsigned long tEnd; // variable to log end time of impact (us)

#include <Wire.h>
#include <Adafruit_LEDBackpack.h>
#include <Adafruit_GFX.h>

Adafruit_7segment matrix = Adafruit_7segment();

void setup() {
  pinMode(ledPin,OUTPUT); // declare ledPin as an OUTPUT
  pinMode(sensor0,INPUT); // declare sensor0 as an INPUT
  Serial.begin(9600);
  matrix.begin(0x70);
}

void loop() {
  matrix.println(impactCount);
  matrix.writeDisplay();

  if (analogRead(sensor0) >= thresholdMin) { // if sensor reading is larger than or equal to minimum threshold
    if (analogRead(sensor0) <= thresholdMax) {// if sensor reading is less than or equal to maximum threshold
      tStart = micros(); // saves impact start time
      while (analogRead(sensor0) >= thresholdMin) { // while sensor reading is above threshold, repeat
      }
      tEnd = micros(); // save impact end time
      deltaT = tEnd - tStart; // calculate deltaT
    }
  }
  if (deltaT >= deltaTmin) { // if deltaT is longer than minimum
    if (deltaT <= deltaTmax) { // if deltaT is shorter than maximum
      impactCount = impactCount + 1; // increment counter
      deltaT = 0; // resets deltaT
      ledState = 1; // set ledState
      digitalWrite(ledPin, ledState); // set ledPin
      delay(ledOn); // delay reset ledState
      ledState = 0; // reset ledState
      digitalWrite(ledPin, ledState); // reset ledPin
    }
  }
}

[rcomito]

Hi mcscott,

If you want to display all leading zeros, try this:

Code: Select all

    // Handle the display one digit at a time to preserve leading zeros.
    matrix.writeDigitNum(0, (impactCount / 1000));
    matrix.writeDigitNum(1, (impactCount/ 100) % 10);
    matrix.writeDigitNum(3, (impactCount / 10) % 10);
    matrix.writeDigitNum(4, impactCount % 10);
    matrix.writeDisplay();

If you just want to display a single zero if there's no impact count yet try:

Code: Select all

    if (impactCount == 0)
        matrix.writeDigitNum(4, 0);
    else
        matrix.print(impactCount);
    matrix.writeDisplay();

Rick Comito

[mcscott]

That did the trick.

Thanks, Rick!

[sparks857]

I recently purchased the #881 7-segment display with backpack. It comes with the #812 4-character led.

My question is about the Adafruit Ind. Product ID# 812 display. The drawing on page 3 of the data sheet, (SPEC NO. w5643E/F REV. NO. V.2) shows the location (from the front,) of the pins on the back. No problem with that, but the drawing seems to indicate it has 12 pins not 14. Elsewhere on the same drawing/page it shows seven pins wide in one view and two pins down in another view for a total of 14 pins just as I would have expected. I have the display and I soldered all 14 pins. I recounted and sure enough, there are 14 pins.

Is this merely a misprint or is there some deeper meaning I'm missing here?

Reason I ask is I'm using it in a non-Arduino application and I'm debugging the thing right now. I'd like to understand the hardware as well as I can to give me the best chance of success.

Thank you,
Tom