STEVAL-STWINBX1 / FP-SNS-DATALOG2 v3.4.0 – battery reported as 0 % (Low Battery) although battery is fully charged; SD logging stops after ~1s
Hello,
I am using a new STEVAL-STWINBX1 with FP-SNS-DATALOG2 v3.4.0 (DATALOG2_Release.bin from the GitHub package, Wi-Fi module updated with EMW3080update v2.3.4). SD logging works correctly when the board is powered via USB. On battery, the logging stops by itself about 1 second after pressing USR, every time.
Observations:
- The battery is the original LiPo supplied with the kit. Measured with a multimeter: 4.15 V on the battery and 4.15 V on the battery pins of the board.
- ST BLE Sensor app always shows "battery: 0%", also after more than 2 hours of charging (5 V USB charger).
- On battery the app shows "alarm: Low Battery"; with USB connected it shows "No Alarm".
- The red LED blinks fast while the charger is connected.
- SD card: SanDisk Ultra 16 GB, FAT32, 32 KB allocation unit. Logging on USB power runs without errors (sd_failed = false).
- With the battery disconnected the firmware also reports 0 %, i.e. the reading does not change between 0 V and 4.15 V.
From the source code, the battery percentage is computed from the ADC reading in BCAdcDriver (3.0 V = 0 %, 4.2 V = 100 %), and DatalogAppTask stops SD logging when the level is below 10 % and the status is discharging. A reported 0 % therefore means the firmware measures 3.0 V or less, while the real voltage is 4.15 V. It looks like the battery voltage measurement path (STBC02 BATMS / ADC4) returns an invalid value.
Questions:
1. Is this a known issue with DATALOG2 v3.4.0 on STWIN.box, or does it indicate a hardware fault on the STBC02 measurement path of my board?
2. Is there a recommended way to verify the battery measurement (e.g. with the default firmware)?
3. Is there a fix or a configuration option to avoid the forced stop of logging?
Thank you.