Problems while using tlc5940 + uno + 6 digit 7 segment display

Projects General Guidance
1

Hi, so i have the following issue.

When driving the 7 segment display the tlc takes about a millisecond to change the channels which seems waaay too long, especially since the data sheet of the tlc touts a 30mhz data rate. How did i notice the problem?: Well unless i change the delayMicroseconds(value) line to value = 1000 the number that is displayed on the previous digit is also displayed on the next digit for a short while. Does anybody know why tlc5940 might be so slow to do anything or even how i can fix it?

Code:

< /* Atmega328p based speedometer
    written by 
    updated last:
    19.05.21
*/

#include "FRAM.h"
#include "SparkFun_Tlc5940.h"
#include <FastLED.h>
#define NUM_LEDS 23
#define DATA_PIN 8
#include <stdlib.h>
// Define the array of leds
CRGB leds[NUM_LEDS];

FRAM fram;
uint32_t start;
uint32_t stop;

const static uint8_t kmA = 8;
const static uint8_t kmB = 9;
const static uint8_t kmC = 10;
const static uint8_t kmD = 11;
const static uint8_t kmE = 12;
const static uint8_t kmF = 13;
const static uint8_t kmG = 14;
const static uint8_t kmDP = 15;

const static uint8_t kphA = 0;
const static uint8_t kphB = 1;
const static uint8_t kphC = 2;
const static uint8_t kphD = 3;
const static uint8_t kphE = 4;
const static uint8_t kphF = 5;
const static uint8_t kphG = 6;
const static uint8_t kphDP = 7;

const static uint8_t kmPin0 = 0;
const static uint8_t kmPin1 = 1;
const static uint8_t kmPin2 = 4;
const static uint8_t kmPin3 = 5;
const static uint8_t kmPin4 = 6;
const static uint8_t kmPin5 = 7;
const static uint8_t kmPins[6] = {0, 1, 4, 5, 6, 7};

const static uint8_t kphPin0 = A1;
const static uint8_t kphPin1 = A2;
const static uint8_t kphPin2 = A3;
const static uint8_t kphPins[6] = {A1, A2, A3};

const static uint8_t buttonPin = 12;
const static uint8_t pulseInputPin = 2;
const static uint8_t dimPin = A0;

//don't use the next 10 adresses after these
const static uint8_t kmstandAddress = 0x60;
const static uint8_t kmstandAddressBackup = 0x70;
const static uint8_t pulsesAddress = 0x80;
const static uint8_t pulsesAddressBackup = 0x90;

//value from 0 to 4095
int brightness = 4000;
int r = 255;
int g = 255;
int b = 255;
int kph = 0;
int kphString[3];
int kmDigit = 0;
int kphDigit = 0;
int shortpresses = 0;
int longpresses = 0;

uint32_t kmstand = 0;
int kmstandString[6];
uint32_t kmstandBackup = 0;
int pulsecounter = 0;
int pulsesPerKm = 0;

float dimFactor = 0.3;

unsigned long timer = 0;
unsigned long last_timer = 0;
unsigned long debouncer_timer = 0;
unsigned long pressstart = 0;
unsigned long tenPulseTimer = 0;
unsigned long digitTimer = 0;
unsigned long pressTimer = 0;

boolean displaychange = false;
boolean debouncer = false;
boolean pressactivated = false;
boolean longpress = false;
boolean shortpress = false;
boolean calibrationActivated = false;
boolean menuactivated = false;
int t2 = 0;
int t1 = 0;

void display_all(int kphData[3], int kmData[6]) {
  /*
    kmData[0] = 1;
    kmData[1] = 2;
    kmData[2] = 3;
    kmData[3] = 4;
    kmData[4] = 5;
    kmData[5] = 6;
    kmData[6] = "\0";

    kphData[0] = 5;
    kphData[1] = 0;
    kphData[2] = "\0";*/
  if(kphDigit == 0){
    t1 = 2;
  } else {
    t1 = kphDigit - 1;
  }
  if(kmDigit == 0){
    t2 = 5;
  } else {
    t2 = kmDigit - 1;
  }
  digitalWrite(kphPins[t1], HIGH);
  digitalWrite(kmPins[t2], HIGH);
  Tlc.clear();

  if (kphData[0] == 0) {
    kphData[0] = 99;
    if (kphData[1] == 0) {
      kphData[1] = 99;
    }
  }

  if (kmData[0] == 0) {
    kmData[0] = 99;
    if (kmData[1] == 0) {
      kmData[1] = 99;
      if (kmData[2] == 0) {
        kmData[2] = 99;
        if (kmData[3] == 0) {
          kmData[3] = 99;
          if (kmData[4] == 0) {
            kmData[4] = 99;
            if (kmData[5] == 0) {
              kmData[5] = 99;
            }
          }
        }
      }
    }
  }
  
  int value[2];
  value[0] = kphData[kphDigit];
  value[1] = kmData[kmDigit];

  switch (value[0]) {
    case 0:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphD, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphF, brightness);
      break;
    case 1:
      Tlc.set(kphB, brightness);
      Tlc.set(kphC, brightness);
      break;
    case 2:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphG, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphD, brightness);
      break;
    case 3:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphG, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphD, brightness);
      break;
    case 4:
      Tlc.set(kphC, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphG, brightness);
      Tlc.set(kphF, brightness);
      break;
    case 5:
      Tlc.set(kphA, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphD, brightness);
      Tlc.set(kphG, brightness);
      Tlc.set(kphF, brightness);
      break;
    case 6:
      Tlc.set(kphA, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphD, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphF, brightness);
      Tlc.set(kphG, brightness);
      break;
    case 7:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphC, brightness);
      break;
    case 8:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphD, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphF, brightness);
      Tlc.set(kphG, brightness);
      break;
    case 9:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphD, brightness);
      Tlc.set(kphF, brightness);
      Tlc.set(kphG, brightness);
      break;
    case 10:
      Tlc.set(kphA, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphD, brightness);
      Tlc.set(kphF, brightness);
      break;
    case 11:
      Tlc.set(kphA, brightness);
      Tlc.set(kphB, brightness);
      Tlc.set(kphC, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphF, brightness);
      Tlc.set(kphG, brightness);
      break;
    case 12:
      Tlc.set(kphF, brightness);
      Tlc.set(kphE, brightness);
      Tlc.set(kphD, brightness);
      break;
  }

  switch (value[1]) {
    case 0:
      Tlc.set(kmA, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmC, brightness);
      Tlc.set(kmD, brightness);
      Tlc.set(kmE, brightness);
      Tlc.set(kmF, brightness);
      break;
    case 1:
      Tlc.set(kmB, brightness);
      Tlc.set(kmC, brightness);
      break;
    case 2:
      Tlc.set(kmA, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmG, brightness);
      Tlc.set(kmE, brightness);
      Tlc.set(kmD, brightness);
      break;
    case 3:
      Tlc.set(kmA, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmG, brightness);
      Tlc.set(kmC, brightness);
      Tlc.set(kmD, brightness);
      break;
    case 4:
      Tlc.set(kmC, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmG, brightness);
      Tlc.set(kmF, brightness);
      break;
    case 5:
      Tlc.set(kmA, brightness);
      Tlc.set(kmC, brightness);
      Tlc.set(kmD, brightness);
      Tlc.set(kmG, brightness);
      Tlc.set(kmF, brightness);
      break;
    case 6:
      Tlc.set(kmA, brightness);
      Tlc.set(kmC, brightness);
      Tlc.set(kmD, brightness);
      Tlc.set(kmE, brightness);
      Tlc.set(kmF, brightness);
      Tlc.set(kmG, brightness);
      break;
    case 7:
      Tlc.set(kmA, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmC, brightness);
      break;
    case 8:
      Tlc.set(kmA, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmC, brightness);
      Tlc.set(kmD, brightness);
      Tlc.set(kmE, brightness);
      Tlc.set(kmF, brightness);
      Tlc.set(kmG, brightness);
      break;
    case 9:
      Tlc.set(kmA, brightness);
      Tlc.set(kmB, brightness);
      Tlc.set(kmC, brightness);
      Tlc.set(kmD, brightness);
      Tlc.set(kmF, brightness);
      Tlc.set(kmG, brightness);
      break;
  }

  Tlc.update();
  delayMicroseconds(900);
  digitalWrite(kphPins[kphDigit], LOW);
  digitalWrite(kmPins[kmDigit], LOW);

  kphDigit++;
  if (kphDigit >= 3) {
    kphDigit = 0;
  }
  kmDigit++;
  if (kmDigit >= 6) {
    kmDigit = 0;
  }
}


void calibrationMode() {
  kphString[0] = 10;
  kphString[1] = 11;
  kphString[2] = 12;
  display_all(kphString, kmstandString);
  if (longpress) {
    pulsesPerKm = pulsecounter;
    fram.write16(pulsesAddress, pulsecounter);
    fram.write16(pulsesAddressBackup, pulsecounter);
    calibrationActivated = false;
  }
}

void setup() {

  FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);  // GRB ordering is assumed

  pinMode(A1, OUTPUT);
  pinMode(A2, OUTPUT);
  pinMode(A3, OUTPUT);

  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);

  dimFactor = analogRead(dimPin) / 1024;

  //start and check fram
  Wire.begin();
  int rv = fram.begin(0x50);
  uint8_t test = fram.read8(0x50);
  if (test != 0) {
    leds[0] = CRGB::Red;
    FastLED.show();
    delay(100);
    FastLED.clear();
    FastLED.show();
  }

  //read out kmstand from fram
  kmstand = fram.read32(kmstandAddress);
  //test
  if (kmstand == 0) {
    kmstand = 123456;
  }
  kmstandBackup = fram.read32(kmstandAddressBackup);

  pulsesPerKm = fram.read16(pulsesAddress);
  int temp = fram.read16(pulsesAddressBackup);

  //compare normal value to backup value
  if (kmstand != kmstandBackup) {
    leds[1] = CRGB::Red;
    FastLED.show();
    delay(100);
    FastLED.clear();
    FastLED.show();
  }

  if (temp != pulsesPerKm) {
    leds[2] = CRGB::Red;
    FastLED.show();
    delay(100);
    FastLED.clear();
    FastLED.show();
  }

  //Interrupt catches signals from transmission
  attachInterrupt(0, pulsedetector, RISING);

  //segmentdisplay numbers off
  digitalWrite(kmPin0, HIGH);
  digitalWrite(kmPin1, HIGH);
  digitalWrite(kmPin2, HIGH);
  digitalWrite(kmPin3, HIGH);
  digitalWrite(kmPin4, HIGH);
  digitalWrite(kmPin5, HIGH);

  digitalWrite(kphPin0, HIGH);
  digitalWrite(kphPin1, HIGH);
  digitalWrite(kphPin2, HIGH);

  Tlc.init();

  //Serial.begin(9600);

  //Clearing 7 segment displays
  Tlc.clear();
  Tlc.update();

  //Setting km stand

  //Cycling through at leds at beginning

  for (int i = 0; i <= 22; i++) {
    leds[i].setRGB(r,g,b);;
    FastLED.show();
    delay(200);
    leds[i] = CRGB::Black;
    FastLED.show();
  }
  FastLED.clear();
  FastLED.show();

  last_timer = millis();
  leds[21].setRGB(r,g,b);
  leds[22].setRGB(r,g,b);
  FastLED.show();
  delay(500);

  tenPulseTimer = millis();
}

void loop() {

  timer = millis();

  //check for rollover with millis function
  if (last_timer >= timer) {
    last_timer = timer;
    timer = millis();
  }

  if ((timer - pressTimer) >= 5000) {
    menuactivated = false;
    shortpresses = 0;
  }

  //menu
  if (shortpress && !calibrationActivated) {
    shortpresses++;
    menuactivated = true;
    switch (shortpresses) {
      case 1:
        if (longpress) {
          pulsecounter = 0;
          longpress = false;
          calibrationActivated = true;
        }
        break;
    }
  }

  //button debouncer
  if (debouncer) {
    if (debouncer_timer = 0) {
      debouncer_timer = timer;
    }
    if (timer - debouncer_timer > 200) {
      debouncer = false;
      debouncer_timer = 0;
    }
  }

  //check button presses
  if (!debouncer) {
    if (digitalRead(buttonPin)) {
      if (!pressactivated) {
        pressactivated = true;
        pressstart = timer;
      }
    }
    if (!digitalRead(buttonPin)) {
      if (pressactivated) {
        if (timer - pressstart > 2000) {
          longpress = true;
        } else {
          shortpress = true;
        }
        pressTimer = millis();
      }
    }
  }

  //do not change postition of this code!
  if (calibrationActivated) {
    calibrationMode();
    return 0;
  }

  //read out kph
  /*if (pulsecounter == 10) {
    unsigned long tenPulseTime = millis() - tenPulseTimer;
    tenPulseTimer = millis();
    float factor1 = pulsesPerKm / 10;
    float tempOneKm = factor1*tenPulseTime;
    kph = round(3600000/tempOneKm);*/
  kph = 53;


  //displaying speed on round bar graph
  //int barleds = round(kph / 10);
  int barleds = 5;
  for (int i = 0; i <= 20; i++) {
    leds[i] = CRGB::Black;
  }
  for (int i = 0; i <= barleds; i++) {
    leds[22 - i].setRGB(r,g,b);;
  }
  //uint8_t temp = 255;
  //FastLED.setBrightness(temp);
  FastLED.show();

  //test
  kmstand = 123456;

  //displaying kmstand
  if (!menuactivated) {
    kphString[0] = kph / 100 ;
    kphString[1] = (kph % 100) / 10;
    kphString[2] = kph % 10;

    kmstandString[0] = kmstand / 100000;
    kmstandString[1] = (kmstand % 100000) / 10000 ;
    kmstandString[2] = (kmstand % 10000) / 1000 ;
    kmstandString[3] = (kmstand % 1000) / 100 ;
    kmstandString[4] = (kmstand % 100) / 10 ;
    kmstandString[5] = kmstand % 10;
    display_all(kphString, kmstandString);
  }
  last_timer = timer;
  //check if dimmer is on
  //dimFactor = analogRead(dimPin) / 1024;
  dimFactor = 0.3;
  uint8_t dimFactorInt = round(255*dimFactor);
  byte dimFactorByte = dimFactorInt;
  //FastLED.setBrightness(dimFactorInt);
  r = dimFactorInt;
  g = dimFactorInt;
  b = dimFactorInt;
  //check if kilometre was driven and update
  if (pulsecounter > pulsesPerKm) {
    kmstand++;
    pulsecounter = pulsecounter - pulsesPerKm;
    fram.write32(kmstandAddress, kmstand);
    fram.write32(kmstandAddressBackup, kmstand);
  }
  //delay(1);
  /*leds[0] = CRGB::Red;
    FastLED.show();
    delay(200);
    leds[0] = CRGB::Black;
    FastLED.show();*/
}

//detects and counts incoming pulses from transmission
void pulsedetector() {
  pulsecounter++;
} />

Wiring diagramm: 
![Bild_2021-06-25_144656|690x376](upload://iDTPLwrwHgSHXR2J1XAHm0FXPHx.png)
2

A millisecond, or nine hundred microseconds?

That's very, very slow
Did you mean 30MHz?

3

it starts to be stable at one millisecond but that leads to flickering using 6 digits

4

Yes 30MHz
heres the datasheet tlc5940 datasheet

5

Could it be that the arduino spi bus is just that slow?

6

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