I have a 4 digit 7 Segment display I want to change the values on

[cahoon140]

when I use the serial.readstring() and copy to char my 4 digit displays is incorrect. The char value is pre-set and works fine but when I enter a new number the number is not displaying correctly. My goal is to be able to create a manually entered number with a letter.

#include <SevSegShift.h>
//https://arduino.stackexchange.com/questions/79739/74hc595-to-4-digit-7-segment-using-sevsegshift-library
#define SHIFT_PIN_SHCP 6
#define SHIFT_PIN_STCP 5
#define SHIFT_PIN_DS   4
String receivedChar;
char displaystring;
char settings[50] = "32p"; ;

boolean newData = false;

SevSegShift sevseg(SHIFT_PIN_DS, SHIFT_PIN_SHCP, SHIFT_PIN_STCP, 1, true);

void setup() {
  byte numDigits = 4;
  byte digitPins[] = {12, 11, 10, 9}; // These are the PINS of the ** Arduino **
  byte segmentPins[] = {0, 1, 2, 3, 4, 5, 6, 7}; // these are the PINs of the ** Shift register **
  bool resistorsOnSegments = false; // 'false' means resistors are on digit pins
  byte hardwareConfig = COMMON_CATHODE; // See README.md for options
  bool updateWithDelays = false; // Default 'false' is Recommended
  bool leadingZeros = false; // Use 'true' if you'd like to keep the leading zeros
  bool disableDecPoint = false; // Use 'true' if your decimal point doesn't exist or isn't connected
  
  sevseg.begin(hardwareConfig, numDigits, digitPins, segmentPins, resistorsOnSegments, updateWithDelays, leadingZeros, disableDecPoint);
  sevseg.setBrightness(100);
  Serial.begin(9600);
 
}

void loop() {
   recvOneChar();
   showNewData();
   sevseg.setChars(settings);   
  sevseg.refreshDisplay(); // Must run repeatedly; don't use blocking code (ex: delay()) in the loop() function or this won't work right
  
}
void recvOneChar() {
    if (Serial.available() > 0) {
       receivedChar = Serial.readString();
      // receivedChar.replace("\n","");
        newData = true;
    }
}

void showNewData() {
    if (newData == true) {
    strcpy(settings, receivedChar.c_str());
    newData = false;
    }
}

[xfpd]

@cahoon140

displays is incorrect

Give a few examples.

[cahoon140]

When I upload the code the number 32p displays on the 7 segment display. However, if I then open Serial Monitor and type 32p then click send I get a partial 3 a partial p. Or it will put the correct number but then put a weird character in the last display. If I put a larger number it doesn't even get close. Do you want screen shots?

[cahoon140]

I found this example and combined it with my code and it works.

Serial Input Basics - updated

Continued from previous Post Example 3 - A more complete system The simple system in Example 2 will work well with a sympathetic human who does not try to mess it up. But if the computer or person sending the data cannot know when the Arduino is ready to receive there is a real risk that the Arduino will not know where the data starts. If you would like to explore this, change the end marker in the previous program from \n to > so that you can include the end marker in your text for illustrat…

#include <SevSegShift.h>
//https://arduino.stackexchange.com/questions/79739/74hc595-to-4-digit-7-segment-using-sevsegshift-library
#define SHIFT_PIN_SHCP 6
#define SHIFT_PIN_STCP 5
#define SHIFT_PIN_DS   4
//String receivedChar;
//char displaystring;
//char settings[50] = "32p"; ;
const byte numChars = 32;
char receivedChars[numChars];   // an array to store the received data

boolean newData = false;

int dataNumber = 0;             // new for this version

SevSegShift sevseg(SHIFT_PIN_DS, SHIFT_PIN_SHCP, SHIFT_PIN_STCP, 1, true);

void setup() {
  byte numDigits = 4;
  byte digitPins[] = {12, 11, 10, 9}; // These are the PINS of the ** Arduino **
  byte segmentPins[] = {0, 1, 2, 3, 4, 5, 6, 7}; // these are the PINs of the ** Shift register **
  bool resistorsOnSegments = false; // 'false' means resistors are on digit pins
  byte hardwareConfig = COMMON_CATHODE; // See README.md for options
  bool updateWithDelays = false; // Default 'false' is Recommended
  bool leadingZeros = false; // Use 'true' if you'd like to keep the leading zeros
  bool disableDecPoint = false; // Use 'true' if your decimal point doesn't exist or isn't connected
  
  sevseg.begin(hardwareConfig, numDigits, digitPins, segmentPins, resistorsOnSegments, updateWithDelays, leadingZeros, disableDecPoint);
  sevseg.setBrightness(100);
  Serial.begin(9600);
 
}

void loop() {
   
    // Serial.println(receivedChars);
   sevseg.setChars(receivedChars);   
  sevseg.refreshDisplay(); // Must run repeatedly; don't use blocking code (ex: delay()) in the loop() function or this won't work right
   recvWithEndMarker();
    
    showNewNumber();
  
}
void recvWithEndMarker() {
    static byte ndx = 0;
    char endMarker = '\n';
    char rc;
    
    if (Serial.available() > 0) {
        rc = Serial.read();

        if (rc != endMarker) {
            receivedChars[ndx] = rc;
            ndx++;
            if (ndx >= numChars) {
                ndx = numChars - 1;
            }
        }
        else {
            receivedChars[ndx] = '\0'; // terminate the string
            ndx = 0;
            newData = true;
        }
    }
}

void showNewNumber() {
    if (newData == true) {
        dataNumber = 0;             // new for this version
        dataNumber = atoi(receivedChars);   // new for this version
        Serial.print("This just in ... ");
        //Serial.println(receivedChars);
        Serial.print("Data as Number ... ");    // new for this version
        Serial.println(dataNumber);     // new for this version
        newData = false;
    }
}