uart_tx_test.tc

UART TX continuous burst test for oscilloscope verification.

Source on GitHub

// UART TX continuous burst test for oscilloscope verification.
//
// Opens UART on RX=11 TX=12 @ 9600 8N1 (same config as onewire DS2480B).
// Then continuously sends 0xC1 bytes for ~10 seconds with 10 ms gaps.
// At 9600 baud each byte is ~1.04 ms wide → with 10 ms gap that's about
// ~91 bytes / second visible as a steady burst pattern on the TX pin.
//
// Expected on Hans's oscilloscope at GPIO 12:
//   - Idle high (3.3V)
//   - Every ~10 ms: a brief 1.04 ms transmission of 0xC1
//     (start bit low, then 0xC1 = 0b11000001 LSB-first, then stop high)
//   - 10 seconds of activity, then idle high
//
// If Oszi sees nothing during this run: TasmotaSerial / Arduino-ESP32
// HardwareSerial UART1 GPIO-matrix-routing failed silently — script
// thinks it's sending but UART peripheral isn't connected to GPIO 12.
// If Oszi sees the bursts: UART path works → onewire issue is elsewhere
// (chip not responding, etc).

int main() {
    addLog("uart_tx_test: opening UART rx=11 tx=12 @9600");
    int s = serialBegin(11, 12, 9600, 3, 64);
    if (s < 0) {
        addLog("uart_tx_test: serialBegin FAILED");
        return -1;
    }
    addLog("uart_tx_test: opened slot=%d, sending 0xC1 burst", s);

    delay(200);  // let UART settle, give the addLog a chance to flush

    int i = 0;
    while (i < 1000) {        // 1000 × 10 ms = 10 seconds
        serialWriteByte(s, 0xC1);
        delay(10);
        i = i + 1;
    }

    addLog("uart_tx_test: burst done, closing");
    serialClose(s);
    return 0;
}