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The T-Watch 2020 hardware devices

The LilyGo t-watch 2020 is a smart watch, based on the ESP32, which you must program yourself. If you want a fully functional smart watch with analogue and digital time display, step counter ... then do not buy the t-watch 2020!

If however you want to find out how to create your own smart watch with BliueTooth and Internet connectivity using C or MicroPython programming then do buy the t-watch!

The t-watch 2020 features:

  • a dual core ESP32 CPU with BlueTooth and WiFi interfaces
  • 16 MBytes of psram
  • a BMA423 three-axis accelerometer
  • a MAX98357a I2S audio amplifier
  • a AXP202 power management unit
  • a PCF8563 real time clock
  • a 240x240 TFT screen controlled by a ST7789V display controller
  • a touch screen controlled by a FT6236U touch screen controller
  • it supports IR control, a vibration motor
The pinouts can be found at https://t-watch_document-en.readthedocs.io

Here is a photo of the watch. The program shown on the display is not supplied.


Software examining the T-Watch 2020 hardware

The programs described in this section are available on github: https://github.com/uraich/twatch2020_firmware/tree/main/hardware

I2C devices

There are 2 I2C buses on the t-watch. To find out which devices are connected to these buses we can use i2cScanBus[0 or 1].py.

The I2C buses use the following connections:

  I2C bus 0 I2C bus 1
Here is the result:

i2cbus0.png i2cbus1.png
and here is a table relating the I2C addresses to the slave devices:

!I2C slave address !I2C device
I2C bus 0: 0x35 AXP202 Power System Management
I2C bus 0:0x19 BMA432 Triaxial Acceleration Sensor
I2C bus 0:0x51 PCF8563 Real-time Clock and Calendar
I2C bus 1:0x38 FT6236U Touch Screen Controller

Drivers for the T-Watch hardware:

Some time ago a custom version of MicroPython integrating lvgl and all drivers needed to drive the t-watch devices was published on
https://github.com/OPHoperHPO/lilygo-ttgo-twatch-2020-micropython. I got the drivers below , except of the I2S driver, from this source.

-- Uli Raich - 2021-01-08


Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng i2cbus0.png r1 manage 23.2 K 2021-01-25 - 14:17 UliRaich  
PNGpng i2cbus1.png r1 manage 22.5 K 2021-01-25 - 14:17 UliRaich  
PNGpng twatch2020.png r1 manage 57.2 K 2021-01-08 - 10:27 UliRaich  
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Topic revision: r9 - 2021-01-29 - UliRaich
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