j4nk/arduino-lcd-writer
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Removed old comments, fixed high latency issue

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j4nk 2023-12-19 12:49:03 -05:00
parent 753ef6f75f
commit 497de2ec28
2 changed files with 14 additions and 62 deletions
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3
README.md
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@ -35,5 +35,6 @@ By default, uploading this program and then writing to the serial device doesn't
3. Write stuff to the serial device - now it should work 3. Write stuff to the serial device - now it should work
### Previously was working ### Previously was working
I basically had to rewrite this from scratch - the Arduino had the program uploaded on it but I lost the code. That version had fast refresh rates but this one takes like 2 seconds to refresh the LCD. I don't have any applications that would break due to this so it isn't important. I basically had to rewrite this from scratch - the Arduino had the program uploaded on it but I lost the code. ~~That version had fast refresh rates but this one takes like 2 seconds to refresh the LCD. I don't have any applications that would break due to this so it isn't important. ~~
I fixed this issue. Apparently `Serial.readString()` is extremely slow, but `Serial.readStringUntil('\n')` (equivalent in this case) is much faster. Not sure on why but it works. I have effectively instant updates now.

73
main.cpp
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@ -1,85 +1,36 @@
/*
LiquidCrystal Library - Hello World
Demonstrates the use a 16x2 LCD display. The LiquidCrystal
library works with all LCD displays that are compatible with the
Hitachi HD44780 driver. There are many of them out there, and you
can usually tell them by the 16-pin interface.
This sketch prints "Hello World!" to the LCD
and shows the time.
The circuit:
* LCD RS pin to digital pin 12
* LCD Enable pin to digital pin 11
* LCD D4 pin to digital pin 5
* LCD D5 pin to digital pin 4
* LCD D6 pin to digital pin 3
* LCD D7 pin to digital pin 2
* LCD R/W pin to ground
* LCD VSS pin to ground
* LCD VCC pin to 5V
* 10K resistor:
* ends to +5V and ground
* wiper to LCD VO pin (pin 3)
Library originally added 18 Apr 2008
by David A. Mellis
library modified 5 Jul 2009
by Limor Fried (http://www.ladyada.net)
example added 9 Jul 2009
by Tom Igoe
modified 22 Nov 2010
by Tom Igoe
modified 7 Nov 2016
by Arturo Guadalupi
This example code is in the public domain.
https://docs.arduino.cc/learn/electronics/lcd-displays
*/
// include the library code: // include the library code:
#include <Arduino.h> #include <Arduino.h>
#include <LiquidCrystal.h> #include <LiquidCrystal.h>
//#include <Time.h>
// initialize the library by associating any needed LCD interface pin // initialize the library by associating any needed LCD interface pin
// with the arduino pin number it is connected to // with the arduino pin number it is connected to
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2; const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7); LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
char buffer_line1[16];
char buffer_line2[16];
void setup() { void setup() {
Serial.begin(115200); Serial.begin(115200);
// set up the LCD's number of columns and rows: // set up the LCD's number of columns and rows:
lcd.begin(16, 2); lcd.begin(16, 2);
lcd.clear(); lcd.clear();
// Print a message to the LCD.
//lcd.print("hello, world!");
} }
void loop() { void loop() {
// set the cursor to column 0, line 1
// (note: line 1 is the second row, since counting begins with 0):
lcd.setCursor(0, 0);
// print the number of seconds since reset:
//lcd.print(millis() / 1000);
while (Serial.available() == 0) {} while (Serial.available() == 0) {}
//lcd.clear(); lcd.clear();
String s = Serial.readString(); lcd.setCursor(0, 0);
s.trim(); String s1 = Serial.readStringUntil('\n'); // This fixed performance issue
int nl_idx = s.indexOf("?", 0); int nl_idx = s1.indexOf("?", 0);
if (nl_idx == -1) { if (nl_idx == -1) {
lcd.print(s); lcd.print(s1);
} }
else { else {
String l1 = s.substring(0, nl_idx); String s2 = s1.substring(nl_idx+1, s1.length());
String l2 = s.substring(nl_idx+1, s.length()); s1 = s1.substring(0, nl_idx);
lcd.print(l1); lcd.print(s1);
lcd.setCursor(0, 1); lcd.setCursor(0, 1);
lcd.print(l2); lcd.print(s2);
} }
} }