arduino: set pin 4 to high/low based on byte received through serial interface

.gitattributes

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+*.jpg filter=lfs diff=lfs merge=lfs -text

.gitignore

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+/build-*/

Makefile

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+BOARD_TAG = uno
+include /usr/share/arduino/Arduino.mk

arduino-sketch.ino

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+const uint8_t PIN = 4;
+
+void setup() {
+    // $ stty -F /dev/ttyUSB0 | grep speed
+    Serial.begin(115200);
+    pinMode(PIN, OUTPUT);
+}
+
+void loop() {
+    // https://www.arduino.cc/reference/en/language/functions/communication/serial/read/
+    if (Serial.available() > 0) {
+        // $ printf '\0' > /dev/ttyUSB0
+        // $ printf '\x01' > /dev/ttyUSB0
+        digitalWrite(PIN, (Serial.read() > 0) ? HIGH : LOW);
+    }
+}