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I am trying use a HMI display. If I want to send a data, for example I want to write "TOPWAY" to 0x00000080 address it should like that:

 Serial.write(0xaa); // packet head Serial.write(0x42); // VP_N16 string write command Serial.write(0x00); // VP_N16 address Serial.write(0x00); Serial.write(0x00); Serial.write(0x80); Serial.write(0x54); //T Serial.write(0x4f); //O Serial.write(0x50); //P Serial.write(0x57); //W Serial.write(0x41); //A Serial.write(0x59); //Y Serial.write(0x00); //string end with "\0" Serial.write(0xcc); // packet tail Serial.write(0x33); // packet tail Serial.write(0xc3); // packet tail Serial.write(0x3c); // packet tail

I want to make a method like SendString(String abc) to send that like above. I need convert string a hex array and call in Serial.write(array[i]). Can you hep me?

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    There is no such thing as a hex array. Everything is all just numbers. Even letters are numbers. Your string is already an array. Commented Jul 28, 2021 at 7:30
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    Serial.print("TOPWAY"); should do it Commented Jul 28, 2021 at 8:18
  • @Juraj you mean like that for total query like above: Serial.write(0xaa); Serial.write(0x42); Serial.write(0x00); Serial.write(0x00); Serial.write(0x00); Serial.write(0x80); Serial.print("TOPWAY"); Serial.write(0x00); //string end with "\0" Serial.write(0xcc); Serial.write(0x33); Serial.write(0xc3); Serial.write(0x3c); . if Not? please show me as answer not in comment. Commented Jul 28, 2021 at 14:37
  • the answer is below Commented Jul 28, 2021 at 14:44

1 Answer 1

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I don't know anything about the particular display, but based on the information provided I hope this is at least shows the foundation of one way you could approach a final solution.

Update:

  • Incorporated great improvements and a fix from Edgar in the comments.
  • String overload.
  • Display baud rate suggested by mehmet
#define DISPLAY_DEVICE Serial #define DISPLAY_DEVICE_BAUD 9600 static uint8_t displayPktStart[] = { 0xaa, // packet headchar 0x42, // VP_N16 string write command 0x00, // VP_N16 address 0x00, // ...Fill 0x00, 0x80 }; static uint8_t displayPktEnd[] = { 0x00, // End of text 0xcc, // packet tail 0x33, // packet tail 0xc3, // packet tail 0x3c // packet tail }; void writeDisplay(const char* text) { // Write packet headers DISPLAY_DEVICE.write(displayPktStart, sizeof displayPktStart); // Send text DISPLAY_DEVICE.print(text); // Write packet tail DISPLAY_DEVICE.write(displayPktEnd, sizeof displayPktEnd); } void writeDisplay(const String& text) { writeDisplay(text.c_str()); } void setup() { DISPLAY_DEVICE.begin(DISPLAY_DEVICE_BAUD); } void loop() { String msg = "TOPWAY"; writeDisplay(msg); delay(2000); writeDisplay("Peanuts taste like chicken"); delay(500); writeDisplay(""); delay(1000); writeDisplay("No. Seriously"); delay(2000); }
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    1. Instead of writing a loop, you can DISPLAY_DEVICE.write(displayPktStart, sizeof displayPktStart);, and likewise for displayPktEnd. 2. You mean DISPLAY_DEVICE.print(text);, not println(). 3. Serial.print() will not send the terminating \0, you may want to add that to displayPktEnd. Commented Jul 28, 2021 at 9:39
  • @EdgarBonet Thanks. Updated. Commented Jul 28, 2021 at 10:04
  • Thanks A lot. I've added DISPLAY_DEVICE.begin(9600); in setup Commented Jul 28, 2021 at 14:51
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    @mehmet I hope my update matches your expectations. Commented Jul 28, 2021 at 15:29
  • @voidPointer well, I don't want to bother you too much, but I have one more question. if I want to use dynamic address, such as "000080" instead of Serial.write(0x00); Serial.write(0x00); Serial.write(0x80); how to add this method, like writeDisplay(msg, "000080"); Commented Jul 28, 2021 at 19:51

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