Wellue FS20F pulse oximeter logger

Python script for connecting to and parsing data from the ~$30 Wellue FS20F pulse oximeter (Bluetooth model).

Usage

Install bluepy (requires Linux) and run with

sudo python fs20f_logger.py <MAC_ADDRESS>

where <MAC_ADDRESS> is the MAC address of your FS20F (find "VTM 20F" with a BLE sniffer like nRF Connect on Android/iOS).

The script will keep trying to connect (and reconnect when disconnected) and print output in JSON, like this (see also sample_output.json):

{"type": "wave", "unknown_1": 0, "unknown_2": 29, "counter": 129, "ppg": 54, "spo2_wave_val": 8, "sensor_off": false, "parse_time": 1601991825.1619356}
{"type": "wave", "unknown_1": 0, "unknown_2": 30, "counter": 130, "ppg": 54, "spo2_wave_val": 8, "sensor_off": false, "parse_time": 1601991825.1625514}
{"type": "wave", "unknown_1": 0, "unknown_2": 31, "counter": 131, "ppg": 54, "spo2_wave_val": 8, "sensor_off": false, "parse_time": 1601991825.191919}
{"type": "wave", "unknown_1": 0, "unknown_2": 33, "counter": 132, "ppg": 55, "spo2_wave_val": 8, "sensor_off": false, "parse_time": 1601991825.251962}
{"type": "param", "unknown_1": 146, "pulse_rate": 78, "spo2": 99, "counter": 18, "perfusion_index": 4.702, "parse_time": 1601991825.252156}
{"type": "wave", "unknown_1": 0, "unknown_2": 35, "counter": 133, "ppg": 56, "spo2_wave_val": 8, "sensor_off": false, "parse_time": 1601991825.2524467}
{"type": "wave", "unknown_1": 0, "unknown_2": 39, "counter": 134, "ppg": 58, "spo2_wave_val": 9, "sensor_off": false, "parse_time": 1601991825.2532318}
{"type": "wave", "unknown_1": 0, "unknown_2": 43, "counter": 135, "ppg": 61, "spo2_wave_val": 9, "sensor_off": false, "parse_time": 1601991825.2818196}

Simple continuous Sp02 logger

This command will automatically log Sp02 readings to the file log.json anytime your FS20F is turned on (and in Bluetooth range):

sudo python fs20f_logger.py <MAC_ADDRESS> | grep param > log.json

The resulting file can be read with pandas using pd.read_json('log.json', lines=True).

Note that the FS20F will not turn off while measuring, so you could potentially log Sp02 over many hours this way (e.g. overnight).

Details

Upon connecting, the FS20F (which advertises itself as "VTM 20F") will automatically start publishing binary data under attribute FFE4. Some sample raw data is included in the file sample_raw_data.hex.

Two types of messages are published:

1. wave data at 50 Hz with photoplethysmogram (PPG) waveform data.
2. parameter data at 1 Hz with SpO2, pulse rate and perfusion index data.

There are a couple other fields that are currently unknown, which are parsed as unknown_X (they don't seem very important). Field spo2_wave_val seems to be a scaled version of ppg, so probably use the latter.