QSP protocol implementation

.vscode/arduino.json

@@ -0,0 +1,6 @@
+{
+    "board": "arduino:avr:pro",
+    "configuration": "cpu=16MHzatmega328",
+    "sketch": "crossbow.ino",
+    "port": "COM5"
+}

.vscode/c_cpp_properties.json

@@ -0,0 +1,21 @@
+{
+    "configurations": [
+        {
+            "name": "Win32",
+            "includePath": [
+                "C:\\Users\\pspyc\\AppData\\Local\\Arduino15\\packages\\arduino\\hardware\\avr\\1.6.19\\cores\\arduino",
+                "C:\\Users\\pspyc\\Documents\\Arduino\\libraries\\PPMReader"
+            ],
+            "browse": {
+                "limitSymbolsToIncludedHeaders": false,
+                "path": [
+                    "C:\\Users\\pspyc\\AppData\\Local\\Arduino15\\packages\\arduino\\hardware\\avr\\1.6.19\\cores\\arduino",
+                    "${workspaceRoot}",
+                    "C:\\Users\\pspyc\\Documents\\Arduino\\libraries\\PPMReader"
+                ]
+            },
+            "intelliSenseMode": "msvc-x64"
+        }
+    ],
+    "version": 3
+}

common.h

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+//Only for UART connected radio modules
+#define UART_SPEED 57600
+
+#define CHANNEL_ID 0x01
+#define QSP_PREAMBLE 0x51
+#define QSP_PAYLOAD_LENGTH 32
+
+#define PIN_LED 13
+
+enum dataStates {
+    IDLE,
+    PREAMBLE_RECEIVED,
+    CHANNEL_RECEIVED,
+    FRAME_TYPE_RECEIVED,
+    PACKET_ID_RECEIVED,
+    PAYLOAD_RECEIVED,
+    CRC_RECEIVED
+};

crossbow.ino

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+// #define DEVICE_MODE_TX
+#define DEVICE_MODE_RX
+
+#ifdef DEVICE_MODE_TX
+
+/*
+ * Main defines for device working in TX mode
+ */
+
+#include <PPMReader.h>
+
+#define PPM_INPUT_PIN       2
+#define PPM_INPUT_INTERRUPT 0
+
+PPMReader ppmReader(PPM_INPUT_PIN, PPM_INPUT_INTERRUPT);
+
+#endif
+
+#ifdef DEVICE_MODE_RX
+
+#include <Adafruit_SSD1306.h>
+
+#define OLED_RESET 4
+Adafruit_SSD1306 display(OLED_RESET);
+
+#endif
+
+static uint8_t protocolState = IDLE;
+static uint8_t packetId = 0;
+static uint8_t qspCrc = 0;
+static uint8_t qspPayload[QSP_PAYLOAD_LENGTH] = {0};
+
+void writeToRadio(uint8_t dataByte) {
+    //Compute CRC
+    qspCrc ^= dataByte;
+
+    //Write to radio
+    Serial.write(dataByte);
+}
+
+void decodeIncomingQspFrame(uint8_t incomingByte) {
+
+    static uint8_t frameId;
+    static uint8_t payloadLength;
+    static uint8_t receivedPayload;
+    static uint8_t packetId; //TODO move this to global scope maybe?
+
+    if (protocolState == IDLE && incomingByte == QSP_PREAMBLE) {
+        //If in IDLE and correct preamble comes, start to decode frame
+        protocolState = PREAMBLE_RECEIVED;
+        qspCrc = 0 ^ incomingByte;
+    } else if (protocolState == PREAMBLE_RECEIVED) {
+        // Check if incomming channel ID is the same as receiver
+        if (incomingByte == CHANNEL_ID) {
+            protocolState = CHANNEL_RECEIVED;
+            qspCrc ^= incomingByte;
+
+            for (uint8_t i = 0; i < QSP_PAYLOAD_LENGTH; i++) {
+                qspPayload[i] = 0x00;
+            }
+
+            receivedPayload = 0;
+            packetId = 0;
+        } else {
+            protocolState = IDLE;
+        }
+    } else if (protocolState == CHANNEL_RECEIVED) {
+        //Frame ID and payload length
+        qspCrc ^= incomingByte;
+
+        frameId = (incomingByte >> 4) & 0x0f;
+        payloadLength = incomingByte & 0x0f;
+
+        protocolState = FRAME_TYPE_RECEIVED;
+
+    } else if (protocolState == FRAME_TYPE_RECEIVED) {
+        qspCrc ^= incomingByte;
+        packetId = incomingByte;
+        protocolState = PACKET_ID_RECEIVED;
+    } else if (protocolState == PACKET_ID_RECEIVED) {
+
+        //Now it's time for payload
+        qspCrc ^= incomingByte;
+        qspPayload[receivedPayload] = incomingByte;
+
+        receivedPayload++;
+
+        if (receivedPayload == payloadLength) {
+            protocolState = PAYLOAD_RECEIVED;    
+        }
+
+    } else if (protocolState == PAYLOAD_RECEIVED) {
+
+        if (qspCrc == incomingByte) {
+            display.clearDisplay();
+            display.setCursor(0, 0);
+            display.print(qspPayload[0]); 
+        
+            display.setCursor(0, 10);
+            display.print(qspPayload[1]); 
+        
+            display.setCursor(0, 20);
+            display.print(qspPayload[2]); 
+        
+            display.setCursor(0, 30);
+            display.print(qspPayload[3]); 
+        
+            display.display(); 
+        } else {
+
+            display.clearDisplay();
+            display.setCursor(0, 0);
+            display.print("CRC failed"); 
+            display.display(); 
+
+        }
+
+        protocolState = IDLE;
+    }
+
+}
+
+uint8_t getPacketId() {
+    return packetId++;
+}
+
+void encodeQspFrame(uint8_t frameId, uint8_t length, uint8_t *payload) {
+    //Zero CRC
+    qspCrc = 0;
+    
+    //Write preamble
+    writeToRadio(QSP_PREAMBLE);
+    //Write CHANNEL_ID
+    writeToRadio(CHANNEL_ID);
+
+    //Write frame type and length
+    uint8_t data = length & 0x0f;
+    data |= (frameId << 4) & 0xf0;
+    writeToRadio(data);
+
+    //Write packet ID
+    writeToRadio(getPacketId());
+
+    //Write payload
+    for (uint8_t i = 0; i < length; i++) {
+        writeToRadio(payload[i]);
+    }
+
+    //Finally write CRC
+    writeToRadio(qspCrc);
+}
+
+void setup(void) {
+    Serial.begin(UART_SPEED);
+
+#ifdef DEVICE_MODE_RX
+    pinMode(PIN_LED, OUTPUT);
+
+    /*
+     * Initialize OLED display
+     */
+    display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  // initialize with the I2C addr 0x3C (for the 128x32)
+    display.setTextSize(1);
+    display.setTextColor(WHITE);
+    display.clearDisplay();
+    display.display();
+
+#endif
+}
+
+void loop(void) {
+
+#ifdef DEVICE_MODE_TX
+    uint8_t pp[4] = {0x41, 0x42, 0x43, 0x44};
+
+    encodeQspFrame(0x01, 0x04, pp);
+
+    Serial.end();
+    delay(30);
+    Serial.begin(UART_SPEED);
+    delay(1000);
+#endif
+
+#ifdef DEVICE_MODE_RX
+    
+    if (Serial.available()) {
+        decodeIncomingQspFrame(Serial.read());
+    }
+
+#endif
+}