TheT-watch2020Hardware < IoT_Course

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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 [[https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bma423-ds000.pdf][BMA423]] three-axis accelerometer
   * a [[https://datasheets.maximintegrated.com/en/ds/MAX98357A-MAX98357B.pdf][MAX98357a]] !I2S audio amplifier
   * a [[http://dl.linux-sunxi.org/AXP/AXP202%20Datasheet_v1.0_en.pdf][AXP202 ]]power management unit
   * a [[https://www.nxp.com/docs/en/data-sheet/PCF8563.pdf][PCF8563]] real time clock
   * a 240x240 TFT screen controlled by a [[https://newhavendisplay.com/appnotes/datasheets/LCDs/ST7789V.pdf][ST7789V ]]display controller
   * a touch screen controlled by a [[https://www.buydisplay.com/download/ic/FT6236-FT6336-FT6436L-FT6436_Datasheet.pdf][FT6236U ]]touch screen controller
   * it supports IR control, a vibration motor
The pinouts can be found at [[https://t-watch-document-en.readthedocs.io/en/latest/introduction/product/2020.html#descriptionhttps?spm=a2g0o.detail.1000023.19.194e16c8jvtOOI][https://t-watch_document-en.readthedocs.io]]

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

<img alt="twatch2020.png" src="%ATTACHURL%/twatch2020.png" title="twatch2020.png" />
---++ 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 |
| SCL | GPIO 22 | GPIO 32 |
| SDA | GPIO 21 | GPIO 23 |
Here is the result:

| <img alt="i2cbus0.png" height="418" src="%ATTACHURL%/i2cbus0.png" title="i2cbus0.png" width="606" /> | <img alt="i2cbus1.png" height="416" src="%ATTACHURL%/i2cbus1.png" title="i2cbus1.png" width="586" /> |
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<br /> https://github.com/OPHoperHPO/lilygo-ttgo-twatch-2020-micropython. I got the drivers below , except of the !I2S driver, from this source.

   * The [[st7789_lvgl display driver]]
   * The [[ft6x36 touch panel driver]]
   * The Real-time clock and calendar: [[PCF8563 driver]]
   * The Power System Management: [[AXP202 driver]]
   * The Triaxial Acceleration Sensor: [[BMA423 driver]]
   * The Max9837 !I2S Audio Power Amplifier: [[t-watch sound]]
   * The buzzer and vibration motor [[t-watch buzzer]]
   * The IR remote control: [[t-watch IR]]
   * The [[ttgo module]]

-- %USERSIG{UliRaich - 2021-01-08}%

---++ Comments

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