ESP32 KISS TNC V1.1

V1.1 Changelog:

• Reduce PCB size at 65x60MM.
• TRRS connector and separate pins for custom connectors.
• Pin 2 as PTT LED, can connect external LED driven via pin 2.
• Volume controls for Audio in and Audio out to fine tune audio for radio.

Schematics:

PCB:

Gerber & BOM:

Gerber_ESP32-WROOM-TNC-1.1

BOM_ESP32-WROOM-TNC-1.1

Code:

// ESP32 KISS TNC v1.1 //
// https://uhpowerup.com/ //
// Code generated by AI and modified by 2E0UMR //
// use at your own risk //

#include 
#include "BluetoothSerial.h"

#define ATR 25
#define AFR 34
#define PTT 4
#define PTT_LED 2


BluetoothSerial BTSerial; // Bluetooth KISS Interface
bool useBluetooth = false;

// KISS protocol special characters
#define FEND 0xC0 // Frame End
#define FESC 0xDB // Frame Escape
#define TFEND 0xDC // Transposed FEND
#define TFESC 0xDD // Transposed FESC

void setup() {
Serial.begin(115200); // USB Serial KISS
BTSerial.begin("ESP32_KISS_TNC v1.1"); // Bluetooth KISS (Change name as needed)


pinMode(PTT, OUTPUT);
pinMode(PTT_LED, OUTPUT);
digitalWrite(PTT, LOW);
digitalWrite(PTT_LED, LOW);

Serial.println("ESP32 KISS TNC Ready");
}

// Function to send KISS packets over serial/Bluetooth
void sendKISSPacket(uint8_t *data, size_t len) {
Serial.write(FEND);
BTSerial.write(FEND);

for (size_t i = 0; i < len; i++) {
if (data[i] == FEND) {
Serial.write(FESC);
Serial.write(TFEND);
BTSerial.write(FESC);
BTSerial.write(TFEND);
} else if (data[i] == FESC) {
Serial.write(FESC);
Serial.write(TFESC);
BTSerial.write(FESC);
BTSerial.write(TFESC);
} else {
Serial.write(data[i]);
BTSerial.write(data[i]);
}
}
Serial.write(FEND);
BTSerial.write(FEND);
}

// Function to generate AFSK tones (simplified example)
void transmitAFSK(uint8_t *packet, size_t len) {
digitalWrite(PTT, HIGH);
digitalWrite(PTT_LED, HIGH);
delay(50); // Small delay for radio keying

for (size_t i = 0; i < len; i++) {
// Generate 1200 Hz or 2200 Hz based on packet bits
tone(ATR, (packet[i] & 1) ? 2200 : 1200, 10);
delay(10);
}

delay(50); // Hold PTT briefly
digitalWrite(PTT, LOW);
digitalWrite(PTT_LED, LOW);
}

// Function to decode received AFSK audio (simplified)
void receiveAFSK() {
int sample = analogRead(AFR);
if (sample > 2000) { // Threshold for detecting signal
uint8_t receivedPacket[] = { 0x82, 0xA6, 0x40, 0x61, 0xE0, 0x03, 0xF0, 'H', 'e', 'l', 'l', 'o' };
sendKISSPacket(receivedPacket, sizeof(receivedPacket));
}
}

void loop() {
// Check USB Serial for KISS frames
if (Serial.available()) {
uint8_t kissFrame[256];
size_t len = Serial.readBytes(kissFrame, sizeof(kissFrame));
transmitAFSK(kissFrame, len);
}

// Check Bluetooth Serial for KISS frames
if (BTSerial.available()) {
uint8_t kissFrame[256];
size_t len = BTSerial.readBytes(kissFrame, sizeof(kissFrame));
transmitAFSK(kissFrame, len);
}

receiveAFSK(); // Process incoming audio
}

73’s

2E0UMR