Hi all, I'm new to the Arduino as well as C. I'm trying to display a four digit temperature using the Arduino Uno, a 4 digit 7 segment display, and a DS18B20 temperature sensor. I mean to display temperatures as 123.4, as an example. I'm trying to multiplex without using any additional components, like shift registers. My biggest issue so far is a delay in the middle of displaying the four digits. I read that this was because of the DS18B20 delaying the code whenever it takes a temperature reading.
So far I've tried lowering the resolution of temperature data and making the sensor take readings less often, but neither of these seem to have had an effect.
I added a delay(200); to give each digit a delay, rather than have a hard stop in the middle of a value. This made it easier to see the temperature being displayed, which I've found to be accurate.
I'm looking for help writing cleaner multiplexing / digit writing code, as well as some help with the DS18B20 stopping my code so much.
#include <OneWire.h>
#include <DallasTemperature.h>
#define ONE_WIRE_BUS 7 //DS18B20 sends data on pin 7
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
int common[] = {12,11,10,9}; //digit pins
boolean count = false;
boolean shift = false;//count and shift control which digit is displayed
double doub=0.1; //multiplier of temp to read each digit
int c=-1; //power of 0.1 used to read each digit
double temp; //temperature
int digVal; //value of given digit
int digPin; //output pin that controls given digit
int counter=0; //delays temperature reading
void setup()
{
pinMode(0,OUTPUT); //segment A
pinMode(1,OUTPUT); //segment B
pinMode(2,OUTPUT); //segment C
pinMode(3,OUTPUT); //segment D
pinMode(4,OUTPUT); //segment E
pinMode(5,OUTPUT); //segment F
pinMode(6,OUTPUT); //segment G
pinMode(7,OUTPUT);
pinMode(10,OUTPUT);
pinMode(11,OUTPUT);
pinMode(12,OUTPUT);
pinMode(9,OUTPUT);
pinMode(8, OUTPUT); //decimal point
sensors.begin();
sensors.setResolution(0x1F); //sets resolution to 9-bit
}
void loop()
{
doub = pow(0.1, c);
digVal = int(temp*doub)%10;//finds value of given digit
digPin = 12;
if(count) //count flips every loop, shift flips every other loop
shift=shift^true;
//each of these if statements decides which digit to read
//based on booleans shift and count
if(shift && count)
{
digPin=12;
c=2;
digitalWrite(8, LOW);
}
if(shift && !count)
{
digPin=9;
c=1;
digitalWrite(8, LOW);
}
if(!shift && count)
{
digPin = 10;
c=0;
digitalWrite(8, LOW);
}
if(!shift && !count)
{
digPin = 11;
c=-1;
digitalWrite(8, HIGH);
}
changePlace(digPin); //see below
writeDigit(digVal); //see below
delay(200); //unnecessary
count= count^true;
counter++;
if(counter%20==0) //meant to take temp readings every 20 digits
{
sensors.requestTemperatures();
temp = sensors.getTempFByIndex(0);
}
}
void writeDigit(int r) //sets proper pin states to display value r
{ //assumed: 0<=r<=9
int i=0;
boolean leds[7];
leds[0] = !(r==1 || r==4);
leds[1] = !(r==5 || r==6);
leds[2] = !(r==2);
leds[3] = !(r==1 || r==4 || r==7);
leds[4] = (r==2 || r==6 || r==8 || r==0);
leds[5] = !(r==1 || r==2 || r==3 || r==7);
leds[6] = !(r==1 || r==7 || r==0);
clearAll(); //sets all pins to 'off' state
for(i=0; i<7; i++) //sets proper segment pins to 'on' state
{
if(leds[i])
digitalWrite((i), HIGH);
}
}
void clearAll() //sets segment pins to 'off' state
{
int j=0;
for(j=0; j<7; j++)
digitalWrite(j, LOW);
}
void changePlace(int x) //sets pin x as the 'on' digit, turns 'off' all others
{
clearAll();
int h=0;
for(h=0; h<4; h++)
digitalWrite(common[h], HIGH);
digitalWrite(x, LOW);
}
I don't think the issue is with the wiring, because actual correct numbers are being displayed.
Thank you all.
