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.

The 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, CSR8510 chip), 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 very well as PC version, this is an ad hoc implementation to MPY/aioble. The code was also tested with MPY-1.24.0-preview/aioble on ESP32-S3-WROOM-1-N16R8 (see Note 3).

5. Optional

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. These intervals can be reduced to the minimum value of 7_500 (7.5 ms) on ESP32-S3, although I am not sure about the actual connection interval after negotiation.

Modify 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)

With the short intervals, you might have to add a short sleep_ms before reading the notification queue as following.

Modify async def _notified_indicated() in aioble/client.py:

        # Either we started > 1 item, or the wait completed successfully, return
        # the front of the queue.
+       await asyncio.sleep_ms(5)
        return queue.popleft()

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)/block 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/block 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 6 SEP 2024).

• Proprietary XOSS App
  • Android-x86 and TPLink UB400, 00:07:27 (4.2 kbps).
    • Connection interval could not be changed (see Note 4).
• PC/Bleak version
  • Windows10 and TPLink UB400, 00:03:45 (8.4 kbps).
  • Windows11 and Intel wireless, 00:08:41 (3.6 kbps).
• MPY/aioble version
  • MPY/aioble, ESP32-WROOM-32E, 00:07:11 (4.4 kbps).
  • MPY/modified aioble(conn_intervals=11.5 ms), ESP32-WROOM-32E, 00:04:04 (7.7 kbps).
  • MPY/modified aioble(conn_intervals=11.5 ms), ESP32-S3-1-N16R8, 00:03:46 (8.3 kbps).
  • MPY/modified aioble(conn_intervals=7.5 ms), reduced NAK/ACK delays and no garbage-collection, ESP32-S3-1-N16R8, 00:02:42 (11.6 kbps).
    • Further optimization requires a modified firmware with increased tick-rate in FreeRTOS ; CONFIG_FREERTOS_HZ=1000 (which defaults to 100 Hz).
  • MPY(CONFIG_FREERTOS_HZ=1000)/modified aioble(conn_intervals=7.5 ms), optimized delays and no garbage-collection, ESP32-S3-1-N16R8, 00:02:05 (15.0 kbps).

(c.f.) Theoretical limit using 11.5 ms connection interval on MPY/aioble:

1 s / 11.5 ms = 87 connections; 1 connection = 6 packets * 20 bytes (mtu=23); so, 128 bytes (1 block) == 2 connections + 1 connection for ACK.

87 connections/s * (128 bytes / 3 connections) * 8 bits/byte = 29.7 kbps.

On Win11, the limits are 1.9, 5.7 and 22.8 kbps for PowerOptimized (180 ms), Balanced (60 ms) and ThroughputOptimized (15 ms) BLE settings, respectively. There is no API in Bleak on Windows to change this setting though. The measured throughput of 3.6 kbps on Win11 using Intel wireless adaptor (as shown above) suggests Balanced setting. On Linux, the min/max connection intervals might be specified by the user (see below).

4. Conn_min_interval/conn_max_interval on Linux kernels.

Unfortunately, changing the parameters did not work for the XOSS App/Android-x86 in my case.

x86:/ $ su
x86:/ # cat /sys/kernel/debug/bluetooth/hci0/conn_min_interval
40                                                                      # 40 * 1.25  = 50 ms
x86:/ # cat /sys/kernel/debug/bluetooth/hci0/conn_max_interval
56                                                                      # 56 * 1.25 = 70 ms
x86:/ # echo 9 > /sys/kernel/debug/bluetooth/hci0/conn_min_interval     # 9 * 1.25 = 11.25 ms
x86:/ # echo 20 > /sys/kernel/debug/bluetooth/hci0/conn_max_interval    # 20 * 1.25 = 25 ms