Ardunio (soft serial) connect to Smart LCD

background

• 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

1. Config the Smart LCD RS-232C terminal as 38400bps (the highest speed of Arduino UNO soft_serial baud rate)
2. Use the following Arduino UNO code for communication example

// TOPWAY Smart LCD interface with Arduino UNO
// Arduino UNO code used in video (for reference only)
#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) {
;} // 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 smallerequal 20; i++) {delayMicroseconds(1000);}   // symbol smallerequal
}

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: youtu.be/9lg5i9_ERBk (2:28)
• Example Project: SDM-22-0003(SmartLCD_RW_w_ArduinoUNO_sw_serial)(UNO_code_inside)(forYT).zip