Adding Arduino sketch for completely buffering implementation

2020-05-29 21:39:25 +02:00
parent 9073271cd5
commit aa6129723d
1 changed files with 167 additions and 0 deletions
@@ -0,0 +1,167 @@
+/* Implementation which buffers all data before sending. See README. */
+
+/* Start a timer which counts 1 each clock cycle. When it reaches
+ * (hicnt*256)+lowcnt, OCF1A is set. Call waitTimer() to wait until this
+ * bit is set.
+ */
+inline void startTimer(int lowcnt, int hicnt)
+{
+  /* Set count mode and max count*/
+  TCCR1A = 0;
+  OCR1AH = hicnt;
+  OCR1AL = lowcnt;
+
+  /* Stop timer 1 */
+  TCCR1B = 0;
+
+  /* Zero out timer 1 */
+  TCNT1 = 0;
+
+  /* Reset overflow flag */
+  TIFR1 = 2; /* OCF1A */
+
+  /* Start timer with prescaler 1 */
+  TCCR1B = 1;
+}
+
+/* Assembly would be preferred but we're a bit lax on timing requirements */
+#define waitTimer() while ( !(TIFR1 & 0x02 ) ) /* OCF1A */
+
+
+#define LEDPIN 13
+#define IRLED 12
+
+void setup()
+{
+  pinMode(LEDPIN, OUTPUT);
+  digitalWrite(LEDPIN, LOW);
+  pinMode(IRLED, OUTPUT);
+  digitalWrite(IRLED, LOW);
+
+  Serial.begin(9600);
+}
+
+/* 31.47 kHz => 16 MHz / 31.47 kHz = 508 counts (Approx .0318 ms bit length) */
+#define BITLEN_L 0
+#define BITLEN_H 2
+//#define BITLEN_L 252
+//#define BITLEN_H 1
+
+/* 31.47 kHz / (15-1) => 7118 counts (Approx 0.445 ms between bits, or 0.477 ms bit interval or 2098 baud) */
+#define SPACELEN_L 206
+#define SPACELEN_H 28
+//#define SPACELEN_L 206
+//#define SPACELEN_H 27
+
+/* 31.47 kHz / 68 (made up) => 34573 counts (approx 2.16 ms between bytes) */
+/* Trying larger delay so that it sounds more like data from the PC. */
+#define INTERBYTE_L 0
+#define INTERBYTE_H 220
+//#define INTERBYTE_L 13
+//#define INTERBYTE_H 135
+
+/* Number of times to repeat interbyte package between bytes */
+#define INTERBYTE_BYTE 3
+
+/* Number of times to repeat interbyte package between packages */
+#define INTERBYTE_PACKAGE 45
+
+void blastData(unsigned char* data, int datalen)
+{
+  unsigned char curbyte;
+  unsigned int packetLeft = 0;
+  bool past55sync = false;
+  bool pastAAsync = false;
+
+  /* Disable arduino interrupts (temporarily breaks delay, serial, ...) */
+  noInterrupts();
+
+  for (unsigned int i=0; i<datalen; i++) {
+    curbyte = data[i];
+
+    if (curbyte != 0x55) {
+      if (!past55sync) {
+        /* Delay between 0x55-sync and 0xAA-sync - Test if this is necessary. */
+        digitalWrite(LEDPIN, LOW);
+        for (unsigned int ipd=0; ipd<INTERBYTE_PACKAGE; ipd++) {
+          startTimer(INTERBYTE_L, INTERBYTE_H);
+          waitTimer();
+          digitalWrite(LEDPIN, HIGH);
+        }
+      }
+      past55sync = true;
+      if (curbyte != 0xAA) {
+        pastAAsync = true;
+      }
+    }
+
+    if (pastAAsync) {
+      /* Delay before each package */
+      if (packetLeft <= 0) {
+        /* First byte of package is package length, including this length byte */
+        packetLeft = curbyte;
+        
+        digitalWrite(LEDPIN, LOW);
+        for (unsigned int ipd=0; ipd<INTERBYTE_PACKAGE; ipd++) {
+          startTimer(INTERBYTE_L, INTERBYTE_H);
+          waitTimer();
+        }
+        digitalWrite(LEDPIN, HIGH);
+
+      }
+      packetLeft--;
+    }
+
+    /* Start bit */
+    startTimer(BITLEN_L, BITLEN_H);
+    digitalWrite(IRLED, HIGH);
+    waitTimer();
+    startTimer(SPACELEN_L, SPACELEN_H);
+    digitalWrite(IRLED, LOW);
+    waitTimer();
+
+    /* Other bits */
+    for (unsigned int b=0; b<8; b++) {
+      startTimer(BITLEN_L, BITLEN_H);
+      digitalWrite(IRLED, !(curbyte&0x01) );
+      waitTimer();
+      startTimer(SPACELEN_L, SPACELEN_H);
+      digitalWrite(IRLED, LOW);
+      curbyte>>=1;
+      waitTimer();
+    }
+
+    /* Inter-byte delay */
+    for (unsigned int ipd=0; ipd<INTERBYTE_BYTE; ipd++) {
+      startTimer(INTERBYTE_L, INTERBYTE_H);
+      waitTimer();
+    }
+  }
+
+  /* Re-enable arduino interrupts */
+  interrupts();
+
+  digitalWrite(LEDPIN,HIGH);
+}
+
+void loop()
+{
+  size_t datalen;
+  unsigned char* data;
+
+  while (!Serial.available());
+  datalen = (Serial.read()<<8)&0xFF00;
+  while (!Serial.available());
+  datalen += (Serial.read())&0x00FF;
+
+  data=malloc(datalen);
+
+  for (int i=0; i<datalen; i++) {
+    while (!Serial.available());
+    data[i] = Serial.read()&0xFF;
+  }
+
+  blastData(data, datalen);
+
+  free(data);
+}