I have written simple code. I want the 4 relay to turn on/off independently when switch is pressed first time Relay is active low and switch is connected with pull up resistor, initially all relays are active, relay should goes off / on after pressing button How to get rid of this blocking delay ? const int Switch_Pin1 = 4; const int Switch_Pin2 = 5; const int Switch_Pin3 = 6; const int Switch_Pin4 = 7; const int Relay_Pin1 = 8; const int Relay_Pin2 = 9; const int Relay_Pin3 = 10; const int Relay_Pin4 = 12; void setup() { // begin serial port with baud rate 9600bps Serial.begin(9600); pinMode(Switch_Pin1, INPUT); pinMode(Switch_Pin2, INPUT); pinMode(Switch_Pin3, INPUT); pinMode(Switch_Pin4, INPUT); pinMode(Relay_Pin1, OUTPUT); pinMode(Relay_Pin2, OUTPUT); pinMode(Relay_Pin3, INPUT); pinMode(Relay_Pin4, INPUT); digitalWrite(Relay_Pin1, LOW); digitalWrite(Relay_Pin2, LOW); digitalWrite(Relay_Pin3, LOW); digitalWrite(Relay_Pin4, LOW); } void loop() { int Switch_State1 = digitalRead(Switch_Pin1); int Switch_State2 = digitalRead(Switch_Pin2); int Switch_State3 = digitalRead(Switch_Pin3); int Switch_State4 = digitalRead(Switch_Pin4); Serial.println(Switch_State1); Serial1.println(Switch_State2); Serial2.println(Switch_State3); Serial3.println(Switch_State4); if(Switch_State1 == LOW ){ digitalWrite(Relay_Pin1, HIGH); delay(4000); digitalWrite(Relay_Pin1, LOW); } if(Switch_State2 == LOW ){ digitalWrite(Relay_Pin2, HIGH); delay(4000); digitalWrite(Relay_Pin2, LOW); } if(Switch_State3 == LOW ){ digitalWrite(Relay_Pin3, HIGH); delay(4000); digitalWrite(Relay_Pin3, LOW); } if(Switch_State4 == LOW ){ digitalWrite(Relay_Pin4, HIGH); delay(4000); digitalWrite(Relay_Pin4, LOW); } }

[image] 12king: hardware timers There are no hardware timers being used. There are 4 (four) software timers, one for each relay. There is also 1 (one) software timer used for the checkSwitches( ) function. In post #12, there is also 1 (one) software timer used for toggling the heartbeatLED. In the sketch in post #12, we therefore have 6 software timers.

[image] 12king: I have a doubt How many hardware timers are configured None, as you will understand after studying the tutorial linked in post #14.

Your additions look oaky. Words of advice: Review the following attached version. Pay attention to the style and code formatting to see how you can achieve documentation and readability in your projects. In the software that you write, try to follow a similar style. Note: In the following sketch pin 12 was moved over to pin 11. A heartbeatLED was added. This LED gives a good indication if code is blocking; the LED should toggle every 1/2 second. //********************************************^************************************************ // // https://forum.arduino.cc/t/how-to-get-rid-of-this-blocking-delay/1025651 // //********************************************^************************************************ // 0_Arduino_Skeleton_Sketch.ino // // // Version YY/MM/DD Comments // ======= ======== ======================================================== // 1.01 22/08/25 Running code // 1.02 22/08/25 Added code to handle relays 4 and 5, move from pin12 to pin 11 // //********************************************^************************************************ #define RESETtime millis() #define ENABLED true #define DISABLED false #define RelayOFF HIGH #define RelayON LOW #define PUSHED LOW //+5V---[Pullup]---[Input Pin]---[Switch]---GND #define RELEASED HIGH //********************************************^************************************************ const byte Switch1 = 4; const byte Switch2 = 5; const byte Switch3 = 6; const byte Switch4 = 7; const byte Relay1 = 8; const byte Relay2 = 9; const byte Relay3 = 10; const byte Relay4 = 11; const byte heartbeatLED = 13; boolean TimerFlag1 = DISABLED; boolean TimerFlag2 = DISABLED; boolean TimerFlag3 = DISABLED; boolean TimerFlag4 = DISABLED; byte lastSwitch1 = RELEASED; byte lastSwitch2 = RELEASED; byte lastSwitch3 = RELEASED; byte lastSwitch4 = RELEASED; //timing stuff const long interval = 4000ul; unsigned long currentTime; unsigned long heartbeatTime; unsigned long checkSwitchesTime; unsigned long relay1Time; unsigned long relay2Time; unsigned long relay3Time; unsigned long relay4Time; // s e t u p ( ) //********************************************^************************************************ void setup() { Serial.begin(9600); pinMode(Switch1, INPUT_PULLUP); pinMode(Switch2, INPUT_PULLUP); pinMode(Switch3, INPUT_PULLUP); pinMode(Switch4, INPUT_PULLUP); pinMode(heartbeatLED, OUTPUT); pinMode(Relay1, OUTPUT); pinMode(Relay2, OUTPUT); pinMode(Relay3, OUTPUT); pinMode(Relay4, OUTPUT); digitalWrite(Relay1, RelayON); digitalWrite(Relay2, RelayON); digitalWrite(Relay3, RelayON); digitalWrite(Relay4, RelayON); } //END of setup() // l o o p ( ) //********************************************^************************************************ void loop() { //capture the current time in milliseconds currentTime = millis(); //********************************* heartbeat TIMER //is it time to toggle the heartbeatLED (every 500ms)? if (currentTime - heartbeatTime >= 500ul) { //restart this TIMER heartbeatTime = RESETtime; //toggle the heartbeatLED digitalWrite(heartbeatLED, !digitalRead(heartbeatLED)); } //********************************* checkSwitches TIMER //time to check our switches ? if (currentTime - checkSwitchesTime >= 50ul) { //restart this TIMER checkSwitchesTime = RESETtime; checkSwitches(); } //********************************* Relay1 TIMER //if enabled, is this TIMER expired ? if (TimerFlag1 == ENABLED && currentTime - relay1Time >= interval) { //we are now finished with this TIMER TimerFlag1 = DISABLED; digitalWrite(Relay1, RelayON); } //********************************* Relay2 TIMER //if enabled, is this TIMER expired ? if (TimerFlag2 == ENABLED && currentTime - relay2Time >= interval) { //we are now finished with this TIMER TimerFlag2 = DISABLED; digitalWrite(Relay2, RelayON); } //********************************* Relay3 TIMER //if enabled, is this TIMER expired ? if (TimerFlag3 == ENABLED && currentTime - relay3Time >= interval) { //we are now finished with this TIMER TimerFlag3 = DISABLED; digitalWrite(Relay3, RelayON); } //********************************* Relay4 TIMER //if enabled, is this TIMER expired ? if (TimerFlag4 == ENABLED && currentTime - relay4Time >= interval) { //we are now finished with this TIMER TimerFlag4 = DISABLED; digitalWrite(Relay4, RelayON); } //********************************* //other non blocking code goes here //********************************* } //END of loop() // c h e c k S w i t c h e s ( ) //********************************************^************************************************ void checkSwitches() { byte currentState; //********************************* Switch1 currentState = digitalRead(Switch1); //did this switch change state ? if (lastSwitch1 != currentState) { //update to the new state lastSwitch1 = currentState; //if we are not timing, is the switch now pushed ? if (TimerFlag1 == DISABLED && currentState == PUSHED) { //enable this TIMER TimerFlag1 = ENABLED; digitalWrite(Relay1, RelayOFF); //reset this TIMER relay1Time = RESETtime; } } //END of this switch //********************************* Switch2 currentState = digitalRead(Switch2); //did this switch change state ? if (lastSwitch2 != currentState) { //update to the new state lastSwitch2 = currentState; //if we are not timing, is the switch now pushed ? if (TimerFlag2 == DISABLED && currentState == PUSHED) { //enable this TIMER TimerFlag2 = ENABLED; digitalWrite(Relay2, RelayOFF); //reset this TIMER relay2Time = RESETtime; } } //END of this switch //********************************* Switch3 currentState = digitalRead(Switch3); //did this switch change state ? if (lastSwitch3 != currentState) { //update to the new state lastSwitch3 = currentState; //if we are not timing, is the switch now pushed ? if (TimerFlag3 == DISABLED && currentState == PUSHED) { //enable this TIMER TimerFlag3 = ENABLED; digitalWrite(Relay3, RelayOFF); //reset this TIMER relay3Time = RESETtime; } } //END of this switch //********************************* Switch4 currentState = digitalRead(Switch4); //did this switch change state ? if (lastSwitch4 != currentState) { //update to the new state lastSwitch4 = currentState; //if we are not timing, is the switch now pushed ? if (TimerFlag4 == DISABLED && currentState == PUSHED) { //enable this TIMER TimerFlag4 = ENABLED; digitalWrite(Relay4, RelayOFF); //reset this TIMER relay4Time = RESETtime; } } //END of this switch //********************************* } //END of checkSwitches() //********************************************^************************************************

[image] LarryD: Pay attention to the style and code formatting to see how you can achieve documentation and readability in your projects. multiple switches reading work for me, How to read multiple serial port I want to avoid blocking delay mega2560 four ports int count = 0; // count = 0 char input[12]; // character array char * validTags[] = {"0A006FBE33E9", "0E004560173D"}; void setup() { Serial.begin(9600); // begin serial port with baud rate 9600bps Serial1.begin(9600); } void loop() { if(Serial1.available()) { count = 0; If(Serial1.available() && count < 12) // Read 12 characters and store them in input array { input[count] = Serial1.read(); count++; delay(5); } if (count == 12){ count = 0; String Value = input; Serial.println(Value); // Print RFID tag number } for (int t = 0; t < 2; t++) { if (strcmp(validTags[t], input) == 0) { Serial.print("Tag "); } } } }

You can use a non-blocking library such as LED library. The below code: // in loop function digitalWrite(Relay_Pin1, HIGH); delay(4000); digitalWrite(Relay_Pin1, LOW); Can be replaced by a non-blocking code: relay.turnON(); // turn on immediately relay.turnOFF(4000); // turn off after 4 second See this example for more detailed

[image] LarryD: What is the exact Data Format that you expect to receive ? What kind of Data ? How many characters ? What terminator is used ? How much ? I want to receive string of 12 characters I want to read 4 serial port independently and turn on/off relay pin after each reading and comparing string

What is the exact Data Format that you expect to receive ? What kind of Data ? How many characters ? What terminator is used ? How much ?

Ah, I see that you can look in the future. Replying before @LarryD posted his question. :rofl: :rofl: :rofl:

[image] sterretje: Replying before @LarryD posted his question. :scream: if(Serial1.available()) You could use: if(Serial1.available() > 11)

How to get rid of this blocking delay

Projects Programming

sterretje August 26, 2022, 3:24pm 21

See Robin's Serial Input Basics - updated to get some ideas.

Note: Your code in post #19 will not work reliably; serial is slow so the processor might see 3 bytes followed by 5 bytes followed by 4 bytes.

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How to get rid of this blocking delay

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