Arduino: Add full Arduino code

This is the full working Arduino code, for writing and loading.

This shouldn not be used by students.

Arduino/SendCart/SendCart.ino

@@ -0,0 +1,71 @@
+#include <Wire.h>
+#include <inttypes.h>
+
+static const int eeprom_addr = 0b1010000;
+uint8_t pageData[128] = {};
+uint16_t pageAddr = 0;
+
+void write_addr(uint16_t addr) {
+  Wire.write((uint8_t)(addr >> 8));
+  Wire.write((uint8_t)addr);
+}
+
+uint16_t sum_complement(const uint8_t data[128]) {
+        uint16_t sum = 0;
+        for (int i = 0; i<128; i += 2) {
+          sum += (data[i+1] << 8) | data[i];
+        }
+        return -sum;
+}
+
+void setup() {
+
+  Serial.begin(115200);
+  pinMode(LED_BUILTIN, OUTPUT);
+  Wire.begin();
+}
+
+void loop() {
+  char ret[4] = "";
+
+  // put your main code here, to run repeatedly:
+  do {
+    if (!Serial.readBytesUntil('\n', ret, 2))
+      Serial.read();
+  } while (strncmp(ret, "GO", 2) != 0);
+
+  // Reset the EEPROM internal address to 0. It autoincrements after.
+  Wire.beginTransmission(eeprom_addr);
+  write_addr(0);
+  Wire.endTransmission(false);
+
+  digitalWrite(LED_BUILTIN, HIGH);
+  /*
+   * We don't know the size of the cartridge, and it could be the whole EEPROM.
+   * Read and send all the pages (64kiB), it should not impact the final PNG.
+   */
+  for (int i = 0; i < 512; i++) {
+    memset(pageData, 0, 128);
+    // Arduino I2C buffer is 32 bytes, so we need multiple requests per page.
+    for (int j = 0; j < 4; j++) {
+      Wire.requestFrom(eeprom_addr, 32);
+      for (int k = 0; k < 32; k++) {
+        pageData[32*j + k] = Wire.read();
+      }
+    }
+    // Try to send the full page until the recipient ACKs
+    uint16_t page_checksum = sum_complement(pageData);
+    do {
+      memset(ret, 0, 4);
+      size_t written = 0;
+      while (written < 128) {
+        written += Serial.write(pageData + written, min(128 - written, 64));
+      }
+      Serial.write((uint8_t*)&page_checksum, 2);
+      while(!Serial.readBytesUntil('\n', ret, 3));
+      Serial.read();
+    } while(strncmp(ret, "ACK", 3) != 0);
+  }
+
+  digitalWrite(LED_BUILTIN, LOW);
+}