xoss_sync

Python (CPython and Micropython) codes to fetch FIT files from XOSS G+ cyclo-computer over bluetooth (BLE) for you.

(C) 2024 ekspla

A quick/preliminary version of code to use with XOSS G+ GPS cyclo-computer, inspired by f-xoss project.

This code is a modified version of cycsync.py for Cycplus M2, which does not work for my use case as is.

The PC version (xoss_sync.py) was tested with XOSS G+ (gen1), Windows10 on Core-i5, TPLink USB BT dongle (UB400, v4.0), Python-3.8.6 and Bleak-0.22.2 while the Micropython (MPY) version (mpy_xoss_sync.py) with MPY-1.23.0 on ESP32-WROOM-32E, SD card, and aioble.

Features

This script allows you to:

• Obtain a list of data files on your device
• Download data (in FIT fromat) from your device
• See free/usage of storage in your device

Usage (PC version)

1. Install bluetooth low energy interface/driver software on your PC.

2. Check if your device and the PC are paired.

3. Install python (of course).

4. Install bleak:

pip install bleak

5. Download and run the script python xoss_sync.py:

D:\backup\Bicycle\XOSS\python>python xoss_sync.py
Scanning for Bluetooth devices...
Found device: XOSS G-040989 - EC:37:9F:xx:yy:zz
Found target device: XOSS G-040989 - EC:37:9F:xx:yy:zz
Connected to XOSS G-040989
Notifications started
Free Diskspace: 684/8104kb
Successfully wrote combined data to filelist.txt
Skip: 20240713062144.fit
Skip: 20240609141047.fit
Skip: 20240504063456.fit
Skip: 20240525060956.fit
Skip: 20240511055922.fit
Skip: 20240609130215.fit
Skip: 20240608063049.fit
Skip: 20240615062615.fit
Retrieving 20240715062336.fit
Successfully wrote combined data to 20240715062336.fit
Skip: 20240420055014.fit
Skip: 20240427061131.fit
Skip: 20240502061739.fit
Skip: 20240518060936.fit
Skip: 20240707055411.fit
Skip: 20240429060242.fit
Skip: 20240622055813.fit
Skip: 20240629073413.fit
Skip: 20240506053748.fit
Skip: 20240706062605.fit
Skip: 20240601060515.fit

D:\backup\Bicycle\XOSS\python>

Though I tested this only with XOSS G+ (gen1) and Windows10 & 11, combinations of the other XOSS device/OS might work. C.f. Bleak supports Android, MacOS, Windows, and Linux.

Usage (Micropython version)

1. Install SD card/interface on your ESP32 board.

2. Install Micropython (of course).

3. Install aioble:

mpremote mip install aioble

4. Download/install and run the script

>>> import mpy_xoss_sync
>>> mpy_xoss_sync.start()

Though it works well as PC version, this is an adhoc implementation to MPY/aioble; still work-in-progress.

Throughput (see Note 3) can be increased by specifying the optional connection parameters of scan_duration_ms, min_conn_interval_us and max_conn_interval_us as described here.

async def _connect() in aioble/central.py:

-           ble.gap_connect(device.addr_type, device.addr)
+           ble.gap_connect(device.addr_type, device.addr, 5_000, 11_500, 11_500)

Limitation

The script seems to work perfectly for my use case as shown above, but there are possible limitations due mainly to the implementation of YMODEM in part as followings.

• The script expects a transport with MTU of 23, 128-byte data per block, and CRC16/ARC (not CRC16/XMODEM). I am not sure if the SoC(seems to be nRF52832)/software in the XOSS device supports larger MTU or 1024-byte data in YMODEM (see, Notes 1 & 2).

Notes

1. My XOSS-G+ (Gen1) was found to be not changing MTU(23)/data size(128) with Win11 and Bluetooth 5.1 interface, which always requests MTU of 525, while f-xoss project for XOSS-NAV used MTU of 206.

2. The proprietary XOSS App on mobile phone itself seems to support larger MTU/data size by DLE (data length extension) and STX. See, for example this Xingzhe's web site.

3. Sync times using my FIT file of 235,723 bytes were as followings (as of 19 AUG 2024).

• Proprietary XOSS App using Android-x86 on FX-6300, 00:07:27 (4.2 kbps).
• PC/bleak version using Windows10 on Core-i5, 00:03:45 (8.4 kbps).
• MPY/aioble version using MPY-1.23.0 on ESP32-WROOM-32E, 00:07:11 (4.4 kbps).
• MPY/aioble with specific connection parameters using MPY-1.23.0 on ESP32-WROOM-32E, 00:04:04 (7.7 kbps).

(c.f.) Theoretical limit using 11.5 ms conn_interval:

1 s / 11.5 ms = 87 connections; 1 connection = 6 packets * 20 bytes (mtu=23); so, 133 bytes (1 block) == 2 connection + 1 connection for ACK.

87 connections/s * (133 bytes / 3 connections) * 8 bits/byte = 30.8 kbps.