View source for Ardunio (soft serial) connect to Smart LCD

=== background ===
[[File:SDM-22-0003.jpg|right|320x320px]]
* Smart LCD mainly provide RS-232C as interface terminal.
* Arduino board hardware UART with level-shifter (eg.MAX3232) can connect Smart LCD in standard way.
* But the connections conflicts with Arduino Serial Monitor for debugging.
* Where, it can use a soft_serial for Smart LCD command instead. (Soft_serial on Arduino UNO cannot run 115200bps.)

=== how to ===

# Config the Smart LCD RS-232C terminal as 38400bps (the highest speed of Arduino UNO soft_serial baud rate)
# Use the following Arduino UNO code for communication example
 // TOPWAY Smart LCD interface with Arduino UNO&lt;/nowiki&gt;
 // Arduino UNO code used in video (for reference only)
 <nowiki>#</nowiki>include
 SoftwareSerial mySerial(10, 11); // RX=10, TX=11 (SW)
 // RX=0, TX=1 (HW)
 int temp_h=0;
 int temp_l=0;
 int writeback_h=0;
 int writeback_l=0;
 int packet_OK=0;
 void setup() {
 // put your setup code here, to run once:
 // start serial port at 115200 bps:
 Serial.begin(115200);
 while (!Serial) {
 <nowiki>;</nowiki>} // wait for serial port to connect. Needed for native USB port only
 // set the data rate for the SoftwareSerial port
 mySerial.begin(38400);
 }
 
 void loop() {
 // put your main code here, to run repeatedly:
 while (mySerial.available()) {char dummy=mySerial.read();}// clear serial buffer
 mySerial.write((byte)0xaa); // packet head
 mySerial.write((byte)0x3e); // VP_N16 read command
 mySerial.write((byte)0x00); // VP_N16 address
 mySerial.write((byte)0x08);
 mySerial.write((byte)0x00);
 mySerial.write((byte)0x00);
 mySerial.write((byte)0xcc); // packet tail
 mySerial.write((byte)0x33); // packet tail
 mySerial.write((byte)0xc3); // packet tail
 mySerial.write((byte)0x3c); // packet tail
 
 while (!mySerial.available()) {}
 if (mySerial.read()==0xaa) { // packet head
 packet_OK=1;
 while (!mySerial.available()) {}
 if (mySerial.read()==0x3e) { // packet command
 while (!mySerial.available()) {}
 temp_h=mySerial.read(); // read back value high byte
 while (!mySerial.available()) {}
 temp_l=mySerial.read(); // read back value low byte
 while (!mySerial.available()) {}
 if (!(mySerial.read()==0xcc)) {packet_OK=0;} // packet tail
 while (!mySerial.available()) {}
 if (!(mySerial.read()==0x33)) {packet_OK=0;} // packet tail
 while (!mySerial.available()) {}
 if (!(mySerial.read()==0xc3)) {packet_OK=0;} // packet tail
 while (!mySerial.available()) {}
 if (!(mySerial.read()==0x3c)) {packet_OK=0;} // packet tail
 }
 else
 {packet_OK=0;}
 }
 else
 {packet_OK=0;}
 if (packet_OK){
 Serial.print(temp_l,DEC);
 Serial.print("\n");
 writeback_h=temp_h;
 writeback_l=temp_l;
 mySerial.write((byte)0xaa); // packet head
 mySerial.write((byte)0x3d); // VP_N16 write command
 mySerial.write((byte)0x00); // VP_N16 address
 mySerial.write((byte)0x08);
 mySerial.write((byte)0x00);
 mySerial.write((byte)0x02);
 mySerial.write((byte)writeback_h); // VP_N16 data high byte
 mySerial.write((byte)writeback_l); // VP_N16 data low byte
 mySerial.write((byte)0xcc); // packet tail
 mySerial.write((byte)0x33); // packet tail
 mySerial.write((byte)0xc3); // packet tail
 mySerial.write((byte)0x3c); // packet tail
 }
 for (int i = 0; i<=20; i++) {delayMicroseconds(1000);}
 }

=== note. ===

* It is suggested to use hardware serial for production application
* mySerial.write(0x00); and Serial.write(0x00);   may not correctly compile mySerial.write((byte)0x00); and Serial.write((byte)0x00); can be correct 
* Clear UNO's serial buffer before send command can improve working efficiency

=== downloads ===

* Example Model: HMT070ATA-1C
* Example Video: [https://Youtu.be/9lg5i9&#x20;ERBk youtu.be/9lg5i9_ERBk] (2:28)
* Example Project: [[Media:SDM-22-0003(SmartLCD RW w ArduinoUNO sw serial)(UNO code inside)(forYT).zip|SDM-22-0003(SmartLCD_RW_w_ArduinoUNO_sw_serial)(UNO_code_inside)(forYT).zip]]