BLE Xiaomi Mijia measurements collector application

This nrf52840 application scans and retrieves measurements from Xiaomi Mijia LYWSD03MMC devices, which are Bluetooth Low Energy (BLE) devices.

The measurements are embedded into records which are sent over the UART1 interface.

Getting started

You will need :

• Xiaomi Mijia LYWSD03MMC devices with firmware version 1.0.0_0130 custom firmware (https://github.com/pvvx/ATC_MiThermometer) version 3.7.
  • Firmware can be upgraded using "Xiaomi Home" app Telink Flasher for Mi Thermostat (select subcategory : OTA Flasher).
  • Use default settings of the custom firmware.
• nrf52840 based board.
• Zephyr RTOS project + ARM toolchain.

Workspace can be created and application can be imported using west commands :

• west init -m https://github.com/lucasdietrich/zephyr-nrf52840-ble-dev --mr main myworkspace
• west update
• Build project with west build command.
• Flash the application with west -v flash -r nrfjprog --snr XXX command, where XXX is the serial number of the board.

Measurements

Following measurements are periodically collected from Xiaomi devices are :

Symbol	Measurement	Unit	Maximum resolution
T	Temperature	°C	1,00E-02
H	Humidity	%	1,00E+00
Bl	Battery Level	%	1,00E+00
Bv	Battery Voltage	V	1,00E-02

IPC Protocol (UART)

UART configuration is for board nrf52840dk_nrf52840 :

Option	Value
Baudrate	1000000
TX pin	p1.02
RX pin	p1.01
Parity	NONE
Stop bits	1
Data bits	8
RTS/CTS	off
HW flow control	off

And for acn52840 board :

Option	Value
Baudrate	9600
TX pin	TODO
RX pin	TODO
Parity	NONE
Stop bits	1
Data bits	8
RTS/CTS	off
HW flow control	off

The IPC protocol is based on messages of fixed length. IPC frame format is as follows :

LEDS

LED	nrf52840dk_nrf52840	custom_acm52840
BLE	GREEN1	RED
TX	GREEN2	GREEN
RX	GREEN3	ORANGE

LOGS

• nrf52840dk_nrf52840: logging via UART0
• acn52840 : logging using SEGGER RTT
  • Run RTT Client JLinkRTTClient
  • Run debugger JLinkGDBServerCLExe -device nrf52840_xxaa -if SWD

Zephyr application-specific configuration options

Configuration option	Description	Unit	Default Value
CONFIG_XIAOMI_MAX_DEVICES	Size of the table containing Xiaomi Devices		13
CONFIG_ACTIVE_SCAN_DURATION	Active scan duration	Seconds	30
CONFIG_ACTIVE_SCAN_PERIODICITY	Active scan frequency	Seconds	3570
CONFIG_DATAFRAME_MIN_INTERVAL	Minimum interval between two dataframes	Seconds	30

Expected console output

[00:00:00.406,250] <inf> bt_hci_core: HW Variant: nRF52x (0x0002)
[00:00:00.406,250] <inf> bt_hci_core: Firmware: Standard Bluetooth controller (0x00) Version 2.7 Build 1
[00:00:00.407,012] <inf> bt_hci_core: Identity: D3:5F:A1:2E:37:92 (random)
[00:00:00.407,012] <inf> bt_hci_core: HCI: version 5.3 (0x0c) revision 0x0000, manufacturer 0x05f1
[00:00:00.407,012] <inf> bt_hci_core: LMP: version 5.3 (0x0c) subver 0xffff
[00:00:00.407,592] <dbg> io.button_init: Set up button at GPIO_0 pin 11
[00:00:01.303,710] <wrn> ipc: Seq gap 0 -> 101, 100 frames lost
[00:00:06.173,736] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:56:5E:CE (ATC_565ECE) rssi: -65 temp: 2948 hum: 3814 bat: 3051 %: 94
[00:00:06.174,072] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:EC:1C:6D (ATC_EC1C6D) rssi: -66 temp: 2952 hum: 3752 bat: 3080 %: 97
[00:00:06.174,224] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:E0:18:ED (ATC_E018ED) rssi: -56 temp: 3220 hum: 3413 bat: 3038 %: 93
[00:00:06.174,407] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:8D:BA:B4 (ATC_8DBAB4) rssi: -84 temp: 2725 hum: 4401 bat: 2842 %: 71
[00:00:06.174,560] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:68:05:63 (ATC_680563) rssi: -59 temp: 2972 hum: 3916 bat: 2869 %: 74
[00:00:06.174,713] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:0A:1E:38 (ATC_0A1E38) rssi: -63 temp: 2950 hum: 3887 bat: 2836 %: 70
[00:00:06.174,957] <dbg> app.send_data_frame: count = 6, frame_time = 6
[00:00:12.118,438] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:56:5E:CE (ATC_565ECE) rssi: -61 temp: 2948 hum: 3814 bat: 3051 %: 94
[00:00:12.118,774] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:EC:1C:6D (ATC_EC1C6D) rssi: -65 temp: 2952 hum: 3752 bat: 3080 %: 97
[00:00:12.118,927] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:E0:18:ED (ATC_E018ED) rssi: -55 temp: 3216 hum: 3419 bat: 3037 %: 93
[00:00:12.119,079] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:68:05:63 (ATC_680563) rssi: -77 temp: 2972 hum: 3916 bat: 2869 %: 74
[00:00:12.119,232] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:0A:1E:38 (ATC_0A1E38) rssi: -57 temp: 2947 hum: 3884 bat: 2837 %: 70
[00:00:12.119,384] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:28:17:E3 (ATC_2817E3) rssi: -66 temp: 2953 hum: 3878 bat: 3045 %: 93
[00:00:12.119,567] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:D5:08:40 (ATC_D50840) rssi: -66 temp: 2592 hum: 5004 bat: 2680 %: 53
[00:00:12.119,720] <dbg> app.df_build_dev_iterate_cb: A4:C1:38:A7:30:C4 (ATC_A730C4) rssi: -65 temp: 2957 hum: 3949 bat: 2593 %: 43
[00:00:12.119,964] <dbg> app.send_data_frame: count = 8, frame_time = 12

Custom board acn52840

Check if board is found using : west boards --board-root . | grep acn52840

VS Code

This project is fully supported by VS Code IDE.

You might need to change tasks environment variables to match your setup in .vscode/tasks.json file.

    "options": {
        "env": {
            "venvPath": "../.venv",
            "westPath": "../.venv/bin/west",
            "netToolsPath": "../tools/net-tools",
            "serialNumber": "683339521"
        }
    },

• You might need to install python with required packages :

  • python -m virtualenv myworkspace/venv
  • source myworkspace/venv/bin/activate
  • pip install -r myworkspace/zephyr/scripts/requirements.txt

• Monitor console screen /dev/ttyACM0 115200

Sources / links :

• lucasdietrich/AVRTOS : src/examples/zephyr-dev-usart-tool/main.c
• ./build/zephyr/zephyr.dts
• ./build/zephyr/include/generated/autoconf.h
• Xiaomi Mijia LYWSD03MMC : Récupérer les données du capteur sur un Raspberry Pi avec gatttool
• Board Porting Guide