From a22b814d63e7dc241b1ffa691b7e36dabaff6621 Mon Sep 17 00:00:00 2001
From: Stephen Olesen <slepp@slepp.ca>
Date: Mon, 13 Jul 2015 18:55:07 -0600
Subject: [PATCH] KISS TNC mode for the AX25 stack and example.

---
 KISS.cpp               | 88 ++++++++++++++++++++++++++++++++++++++++++
 KISS.h                 | 35 +++++++++++++++++
 examples/KISS/KISS.ino | 36 +++++++++++++++++
 3 files changed, 159 insertions(+)
 create mode 100644 KISS.cpp
 create mode 100644 KISS.h
 create mode 100644 examples/KISS/KISS.ino

diff --git a/KISS.cpp b/KISS.cpp
new file mode 100644
index 0000000..06a2115
--- /dev/null
+++ b/KISS.cpp
@@ -0,0 +1,88 @@
+#include <HamShield.h>
+#include "AFSK.h"
+#include "KISS.h"
+
+//AFSK::Packet kissPacket;
+bool inFrame = false;
+uint8_t kissBuffer[PACKET_MAX_LEN];
+uint16_t kissLen = 0;
+
+// Inside the KISS loop, we basically wait for data to come in from the
+// KISS equipment, and look if we have anything to relay along
+void KISS::loop() {
+  static bool currentlySending = false;
+  if(radio->afsk.decoder.read() || radio->afsk.rxPacketCount()) {
+     // A true return means something was put onto the packet FIFO
+     // If we actually have data packets in the buffer, process them all now
+     while(radio->afsk.rxPacketCount()) {
+       AFSK::Packet *packet = radio->afsk.getRXPacket();
+       if(packet) {
+         writePacket(packet);
+         AFSK::PacketBuffer::freePacket(packet);
+       }
+     }
+   }
+   // Check if we have incoming data to turn into a packet
+   if(io->available()) {
+     uint8_t c = (uint8_t)io->read();
+     if(c == KISS_FEND) {
+       if(inFrame && kissLen > 0) {
+         int i;
+         AFSK::Packet *packet = AFSK::PacketBuffer::makePacket(PACKET_MAX_LEN);
+         packet->start();
+         for(i = 0; i < kissLen; i++) {
+           packet->append(kissBuffer[i]);
+         }
+         packet->finish();
+         radio->afsk.encoder.putPacket(packet);
+       }
+       kissLen = 0;
+       inFrame = false;
+     }
+     // We're inside the boundaries of a FEND
+     if(inFrame) {
+       // Unescape the incoming data
+       if(c == KISS_FESC) {
+         c = io->read();
+         if(c == KISS_TFESC) {
+           c = KISS_FESC;
+         } else {
+           c = KISS_FEND;
+         }
+       }
+       kissBuffer[kissLen++] = c;
+     }
+     if(kissLen == 0 && c != KISS_FEND) {
+       if((c & 0xf) == 0) // First byte<3:0> should be a 0, otherwise we're having options
+         inFrame = true;
+     }
+   }
+   if(radio->afsk.txReady()) {
+     radio->setModeTransmit();
+     currentlySending = true;
+     if(!radio->afsk.txStart()) { // Unable to start for some reason
+       radio->setModeReceive();
+       currentlySending = false;
+     }
+   }
+   if(currentlySending && radio->afsk.encoder.isDone()) {
+    radio->setModeReceive();
+    currentlySending = false;
+  }
+}
+
+void KISS::writePacket(AFSK::Packet *p) {
+  int i;
+  io->write(KISS_FEND);
+  io->write((uint8_t)0); // Host to TNC port identifier
+  for(i = 0; i < p->len-2; i++) {
+    char c = p->getByte(i);
+    if(c == KISS_FEND || c == KISS_FESC) {
+      io->write(KISS_FESC);
+      io->write((c==KISS_FEND?KISS_TFEND:KISS_TFESC));
+    } else {
+      io->write(c);
+    }
+  }
+  io->write(KISS_FEND);
+}
diff --git a/KISS.h b/KISS.h
new file mode 100644
index 0000000..dd839e6
--- /dev/null
+++ b/KISS.h
@@ -0,0 +1,35 @@
+#ifndef _KISS_H_
+#define _KISS_H_
+
+#include <HamShield.h>
+#include "AFSK.h"
+
+#define KISS_FEND 0xC0
+#define KISS_FESC 0xDB
+#define KISS_TFEND 0xDC
+#define KISS_TFESC 0xDD
+
+class KISS {
+public:
+  KISS(Stream *_io, HamShield *h, DDS *d) : io(_io), radio(h), dds(d) {}
+  bool read();
+  void writePacket(AFSK::Packet *);
+  void loop();
+  inline void isr() {
+    static uint8_t tcnt = 0;
+    TIFR1 = _BV(ICF1); // Clear the timer flag
+    dds->clockTick();
+    if(++tcnt == (DDS_REFCLK_DEFAULT/9600)) {
+      PORTD |= _BV(2); // Diagnostic pin (D2)
+      radio->afsk.timer();
+      tcnt = 0;
+    }
+    PORTD &= ~(_BV(2));
+  }
+private:
+  Stream *io;
+  HamShield *radio;
+  DDS *dds;
+};
+
+#endif /* _KISS_H_ */
diff --git a/examples/KISS/KISS.ino b/examples/KISS/KISS.ino
new file mode 100644
index 0000000..7cec7e1
--- /dev/null
+++ b/examples/KISS/KISS.ino
@@ -0,0 +1,36 @@
+#define DDS_REFCLK_DEFAULT 19200
+
+#include <HamShield.h>
+#include <Wire.h>
+#include <KISS.h>
+
+HamShield radio;
+DDS dds;
+KISS kiss(&Serial, &radio, &dds);
+
+void setup() {
+  pinMode(2, OUTPUT);
+  pinMode(3, OUTPUT);
+  pinMode(11, INPUT);
+  
+  Serial.begin(9600);
+  Wire.begin();
+  radio.initialize();
+  radio.setVHF();
+  radio.setSQOff();
+  radio.setFrequency(145010);
+  I2Cdev::writeWord(A1846S_DEV_ADDR_SENLOW, 0x30, 0x06);
+  I2Cdev::writeWord(A1846S_DEV_ADDR_SENLOW, 0x30, 0x26);
+  I2Cdev::writeWord(A1846S_DEV_ADDR_SENLOW, 0x44, 0b0000011111111111);
+
+  dds.start();
+  radio.afsk.start(&dds);
+}
+
+void loop() {
+  kiss.loop();
+}
+
+ISR(ADC_vect) {
+  kiss.isr();
+}