Stop first-boot bootloop on unconfigured HAN RX pin (#1184)

[gskjold]

Problem

Fixes #1184 — WT32-ETH01 (and any WROOM-based ESP32) enters a permanent bootloop on first boot with no configuration.

The reported log:

(setupHanPort) Setting up HAN on pin -1/-1 with baud 2400 and parity 11
Guru Meditation Error: Core 1 panic'ed (IllegalInstruction).

Root cause

On a fresh device, hasConfig() can't validate the EEPROM and forces boardType = 0xFF + clear(), and clearMeter() leaves the meter as GPIO/passive with rxPin = 0xFF, txPin = 0xFF, baud = 0. (This matches the "board type 255 / zero voltage" in the report.)

Each loop, handleMeterConfig() builds a PassiveMeterCommunicator and calls setupHanPort(). The only invalid-pin guard there was if(rxpin == 0). With rxPin = 0xFF (-1 as the int8_t copy) that guard doesn't fire, so it prints pin -1/-1 and proceeds to:

hwSerial->begin(baud, serialConfig, -1, -1, invert);
uart_set_pin(uart_num, txpin, rxpin, -1, -1);   // tx=-1, rx=-1

With rx=-1 the Arduino-ESP32 core falls back to UART1's default pins, which on WROOM modules are the SPI-flash data lines. Rebinding them corrupts flash reads and the next instruction fetch faults → IllegalInstruction panic at a flash address → reset → bootloop. Because this happens before the web server starts, the user can never reach the wizard to select the correct board type.

Fix

Bail out of setupHanPort when rxPin is the unconfigured 0xFF sentinel, the same way pin 0 is already handled. The device then boots cleanly into the AP/config wizard where the board type (243 = WT32-ETH01) can be selected. Covers both callers (PassiveMeterCommunicator::configure and KmpCommunicator).

Verification

src/PassiveMeterCommunicator.cpp is Arduino-dependent firmware, so it isn't covered by the native pio test decoder harness. The change is a single guard matching the existing pin-0 idiom directly below it.

🤖 Generated with Claude Code

[github-actions]

🔧 PR Build Artifacts

Version: c89a41e

All environments built successfully. Download the zip files:

• esp32s2: Download esp32s2.zip
• esp32s3: Download esp32s3.zip
• esp32c3: Download esp32c3.zip
• esp32: Download esp32.zip
• esp32solo: Download esp32solo.zip
• esp8266: Download esp8266.zip

Artifacts expire after 7 days. View workflow run