Reverse engineering the SMA-Q2/SMA-Time smartwatch

by emeryth (emeryth at hackerspace.pl)

Intro

SMA Q2 also known as SMA TIME is a Chinese smartwatch similar in design and features to the Pebble Time.
Featuring a color Memory LCD, heart rate sensor and a NRF52832 Bluetooth SoC to drive it all.

~~All the documents and interesting things are uploaded here: https://owncloud.hackerspace.pl/index.php/s/1bqTRwMI8XKXGKL~~
Follow the project here: https://hackaday.io/project/85463-color-open-source-smartwatch

Firmware

The original watch firmware runs on S132 SoftDevice ver 2.0.1.
The device contains an OTA bootloader that can be used with the generic Nordic upload tool, so new firmwares can be uploaded safely.
Just make sure you have a way to reset the device if you screw up.

Hardware

Important Components

IC	Description	Datasheet
NRF52832-QFAAB0	Main SoC
LP2985 (?)	3.3V LDO for everything
LP2985 (?)	3.3V LDO for heart rate sensor module
???	Battery charger
KX022-1020	3-Axis acccelerometer
PAH8002	Heart rate sensor
GD25Q16C (?)	16Mbit SPI flash
LPM013M126A (?)	176×176 Japan Display Color memory LCD

MCU Pinout

Pin	Description
P0.02	LCD SCLK
P0.03	LCD SI
P0.05	LCD SCS
P0.06	LCD EXTCOMIN
P0.07	LCD DISP

P0.04	Battery voltage measurement (x0.25 divider)

P0.08	BACKLIGHT ON

P0.09	BUTTON BACK
P0.27	BUTTON UP
P0.28	BUTTON OK
P0.29	BUTTON DOWN

P0.11	FLASH MISO
P0.12	FLASH CS
P0.13	FLASH MOSI
P0.14	FLASH CLK

P0.25	UART RX
P0.26	UART TX

P0.30	VIBRATOR ON

P0.15	ACCEL INT ?
P0.16	ACCEL POWER
P0.17	ACCEL SDA
P0.18	ACCEL SCL

P0.19	HRM SDA
P0.20	HRM SCL
P0.22	HRM INT?
P0.10	HRM RESET?
P0.31	HRM POWER ON

sma-q2-oss
Status	active
Founder	emeryth
Source	emeryth/sma-q2-oss

Warszawski Hackerspace

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