Nucleo-WL55JC1集成BME688后阻塞问题排查求助

Key Observations #

• Forced mode works as expected (one-shot measurement then sleep)
• Sleep mode operates normally
• Sequential/Parallel modes cause system hang after first measurement
• LoRaWAN join fails, then system stops after attempting to send data

Troubleshooting Steps & Fixes #

1. Correct Measurement Delay Calculation

Your current delay calculation in SendTxData is incorrect, which can lead to premature data reads and I2C bus lockup:

// Wrong calculation: heatr_dur in Sequential mode is 10ms per unit
del_period = bme68x_get_meas_dur(BME68X_SEQUENTIAL_MODE, &conf, &bme) + (heatr_conf.heatr_dur * 1000);

// Correct calculation: convert heatr_dur (10ms units) to microseconds
del_period = bme68x_get_meas_dur(BME68X_SEQUENTIAL_MODE, &conf, &bme) + (heatr_conf.heatr_dur * 10 * 1000);

The BME68X API defines heatr_dur in Sequential mode as 10ms per unit. Setting heatr_dur=100 means 1000ms of heating time. Your original code only added 100ms of delay, leading to trying to read data before the sensor finishes measuring, which can block the I2C bus indefinitely.

2. Avoid Blocking Delays in LoRaWAN Context

Blocking for extended periods (like 1s+) in SendTxData disrupts the LoRaWAN stack's timing (RX windows, join retries). Instead:

• Use the BME688's data-ready interrupt: connect the sensor's INT pin to an MCU GPIO, configure edge-triggered interrupts, and read data only when the interrupt fires.
• In Forced mode, trigger the measurement, then let the LoRaWAN stack manage sleep until the measurement is complete (use timers instead of blocking delays).

3. Check for I2C Bus Lockup

Add error checking to all BME68X API calls to identify communication failures:

int8_t rslt = bme68x_get_data(BME68X_SEQUENTIAL_MODE, &data, &n_fields, &bme);
if(rslt != BME68X_OK) {
  // Log error code (e.g., BME68X_E_COMM_FAIL for I2C issues)
  printf("BME688 read error: %d\n", rslt);
  // Reset I2C peripheral if needed
  HAL_I2C_DeInit(&hi2c3);
  HAL_I2C_Init(&hi2c3);
}

If you see BME68X_E_COMM_FAIL, the I2C bus is likely locked. Resetting the I2C peripheral can recover from this, but you'll need to find the root cause (incorrect delay, bus conflicts).

4. Resolve Power Management Conflicts

The LoRaWAN stack uses low-power modes (like STOP) to save power. Sequential mode requires the BME688 and I2C peripheral to stay powered, which may conflict with the MCU's sleep states:

• Ensure the sensor's power supply isn't cut when the MCU enters sleep.
• Re-initialize the I2C peripheral and BME688 after wakeup from low-power modes.
• Alternative: Stick to Forced mode, which aligns with LoRaWAN's typical cycle (wake → measure → send → sleep). This avoids continuous sensor operation and power conflicts entirely.

5. Isolate the Sensor Code

Test the BME688 in Sequential mode without the LoRaWAN stack:

• Create a minimal project that initializes I2C and BME688, then reads data in a loop.
• If this works, the issue is a conflict between the sensor's mode and the LoRaWAN stack's timing/power management.
• If it still hangs, check your I2C driver implementation (e.g., bme68x_interface_init functions) for bugs.

6. Verify Variable Scope

Ensure your extern variables (bme, conf, heatr_conf) are not being overwritten by other code. Confirm their values remain consistent between initialization and data read calls (e.g., conf.odr shouldn't change unexpectedly).

Recommended Fix #

Given the constraints of LoRaWAN end nodes (power efficiency, timing sensitivity), Forced mode is the most reliable choice. Modify your workflow to:

1. Wake the MCU from sleep
2. Trigger a Forced mode measurement
3. Wait for data ready (using interrupt or non-blocking timer)
4. Read sensor data
5. Send via LoRaWAN
6. Return to sleep

This avoids the conflicts caused by continuous sensor operation in Sequential/Parallel modes.

内容的提问来源于stack exchange，提问作者Nguyen Huy