TTGO T-Watch ESP32. Which model to choose? Available expansion boards

lilygo TTGO T-Watch ESP32. Which model to choose? Available expansion boards
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LilyGO, the Chinese manufacturer of the TTGO brand, is very prolific. After the ESP32 and ESP8266 development boards, he offers us the T-Watch series which concentrates in a 20mm thick mini case an ESP32 battery-powered development board equipped with a color touch screen (or not). The box can accommodate a specialized expansion board (Lora, GPS, GPRS …). The T-Watch 2020 is a real connected watch with a design reminiscent of the Apple Watch. As it is above all an ESP32 development board, it can be entirely programmed with Arduino code!

 

T-Block et T-Bot

The LilyGo T-Block is an attractive small plastic case ideal for children. The PCB has an ESP32, 8MB of flash memory, 16MB of SPRAM memory, an RTC clock (PCF8563), a 3-axis accelerometer (MPU6050) and an AXP202 power controller that can be driven via the I2C bus with C++ code. The display is entrusted to a 1.54” e-Paper screen.

ttgo lilygo t-block esp32

The T-Bot is a version that integrates an expansion board on which an HC-SR04 ultrasonic proximity sensor is placed. The T-Block is then installed on a base equipped with a motor to transform the T-Bot into a mini robot! Up to 3 analog sensors can be installed on the expansion board in addition to the HC-SR04.

ttgo t-bot HC-SR04 front viewHC-SR04 ttgo lilygo connectors

The T-Block is clearly intended for beginners and offers a fairly limited number of expansion boards (keyboard, LED matrix, e-paper). Past the playful aspect of the case, you quickly risk being limited in your projects.

T-Watch TOUCH et NO TOUCH (2019)

The T-Watch Touch (2019) is an improved version of the T-Block. The e-paper screen has been replaced by a color TFT screen of 1.54 “diagonal available in a touch version or not called T-Watch-N sold in a yellow packaging.

The case measures 40 x 38mm and 20mm thick. It comes with a bracelet that will allow it to be worn on the wrist.

The T-Watch case is clearly not a Smart Watch but has many advantages.

LilyGo has concentrated in this mini box a real SP32 development board. On the Core PCB , the motherboard we find

  • The ESP32 SoS backed by 16MB of Flash memory and 8MB of SPRAM memory
  • A 1.54″ color TFT touch screen (or not) driven by an ST7789V controller supported by the excellent LVGL graphics library
  • A 300mAh LiPo battery sufficient for most applications
  • One user programmable button
  • An external I2C connector
  • An AXP202 power controller that takes care of charging the LiPo battery. CL’AXP202 has several I / Os that can be used to power accessories via the I2C bus!
  • A 3-axis accelerometer BMA423
  • A PCF8563 RTC clock
  • A connector for an expansion board (mandatory for the LiPo battery)

An expansion board is superimposed on the Core PCB. It is needed to connect the LiPo battery.

LilyGo offers 13 specialized expansion boards (in addition to the Basic Expansion Board):

  • Basic Expansion Board (supplied with each T-Watch) , 2 x 8-pin expansion connectors providing access to pins 33, 34, 21 (SDA), 22 (SCL) of ESP32 and IO0, IO1, IO2 and IO3 of the AXP202 (power manager). This is the board delivered as standard
  • T-Fork connector for breadboard
  • GPS and M8N Blox
  • Handle , joystick and 4 buttons to transform the T-Watch into a Gameboy!
  • Motor & Speaker (Pack H329), vibrator + speaker
  • MPR121, external touch interface
  • SIM800L, modem GPRS
  • MP3 , MP3 player
  • NFC , contactless reader (note, this is not an RFID reader)
  • T-Car, can drive up to 3 servo motors via the 1-Wire bus
  • T-Quick , can control up to 2 motors in I2C
  • MAX98357 (Pack H328), I2S audio output
  • S76G Lora + GPS (Pack H327)
  • S78G Lora (433 to 470 MHz) + GPS (Pack H397). LoRa modem

The list is constantly evolving.

Attention, expansion boards are not compatible with the T-Block!
[ wpsm_box]

Most expansion boards have a micro SD card reader accessible without opening the case via a side slot. Difficult to find so compact on the side of traditional ESP32 development boards!

See more expansion boards for the T-Watch

Here, the T-Watch Touch with a Lora + GPS S78G expansion board. The Lora antenna unfortunately comes out of the case via the slot for the bracelet. It can be glued under the case … but be careful when removing it to replace the battery.

lilygo ttgo t-watch touch 2019

Lora + GPS S76G version

9.4Expert Score
Verdict on LilyGo's T-Watch case

The T-Watch case can replace a classic ESP32 development board in many cases. The price / function integration ratio is unbeatable. The color touch screen is a real plus.

Price / function ratio
10
Build quality
9
Specifications
10
Design
8
Expansion possibility
10
PROS
  • Ultra compact format
  • Good quality color touch screen
  • Unbeatable compactness / functionality ratio
  • Easy-access i2c connector
  • LiPo battery
  • AXP202 power controller
CONS
  • No access to Reset without opening the box (replaced by holding 6s on the main button)
  • Molex connector not very widespread and bulky
  • Protective cap of the i2c connector does not hold much

T-Watch 2020, a DIY Apple Watch!

The T-Watch 2020 is a compact version that adopts the design of the Apple Watch. The T-Watch 2020 is above all designed as a connected watch. It adopts exactly the same internal architecture as the T-Watch Touch, which means that the code will work on both boxes.

lilygo ttgo t-watch 2020

However, it does not offer any possibility of extension, nor of GPRS modem. It will therefore be impossible to connect the TWatch 2020 to the internet.

It only has one USB-C standard port for recharging the Li-Ion battery and programming. This is protected by a removable cover (quite difficult to open moreover).

Small regret, the rotation of the crown of the main power button is not functional. It would have been really a plus to navigate the menus: cry:

The bottom cover (very easy to remove) allows access to the 3.7V Li-Ion battery with a capacity of 380mAh for its replacement.

lilygo ttgo t-watch 2020 esp32 back side

Compatible replacement batteries are fairly easy to find.

LiLyGo references two versions of the T-Watch 2020 in the technical documentation on this GitHub page . Version 2 does not appear to be released yet at the time of this writing.

In the event that version 2 is marketed, it should include a GPS receiver (Air 530) as well as a microSD card reader (internal or external, for the moment nothing has been indicated).

Here is a summary table of the main technical characteristics.

FunctionT-Watch 2020 V1T-Watch 2020 V2
ESP32ESP32-DOWDQ6ESP32-DOWDQ6
Flash16MB16MB
SPRAM8MB8MB
Touchscreen resolution 1.54 “240×240240×240
Touch screen driverFT6236FT6236
TFT screen driverST7789ST7789
GPS moduleAir530

Powered by LDO4 port

User buttonRotary + ClickRotary + Click (?)
Micro-USB connectorProtected by a removable hoodx1 (?)
DrumsLiPo 3.7V 300mAh

Data source

]

7.4Expert Score
Verdict on LilyGo's 2020 T-Watch

The design of the 2020 T-Watch is forgotten that it is above all an ESP32 development board. It is a real achievement. The price ratio / functions is excellent. Too bad the crown is not functional. We also regret the absence of an external i2c connector which would have been more true for Makers.

Price / functions ratio
8
Manufacturing quality
9
Specifications
7
Design
8
Possibility of expansion
5
PROS
  • Design of a connected watch
  • ESP32
  • Available memory (16MB + 8MB)
  • Li-Ion battery easy to replace
  • Excellent quality / price ratio
CONS
  • Crown not functional
  • No GPRS modem
  • No GPS in v1

K210 AIOT with OV2640 camera

Unlike the other boxes developed on the basis of the ESP32 from Espressif, the K210 AIOT uses a K210 processor from Kendryte . On paper, the K210 looked promising, but few manufacturers adopted it. Seeed Studio integrated it into several development boards last year, Sipeed M1 and  Sipeed Maixduino in particular.

lilygo k210 you are going to micropython ov2640 camera 2MP

The easiest way to use the camera module is to use the fork of the MaixPy project from LiLyGo. MaixPy uses MicroPython for programming. Here is an example to take a snapshot and display it on the LCD screen of the box.

import sensor
import image
import lcd

lcd.init()
sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.run(1)
while True:
    img=sensor.snapshot()
    lcd.display(img)

It is also possible to develop in C ++ using the library available for the Arduino IDE .

The project is enticing on paper, remains to be seen if it will continue to be maintained and supported by SeedStudio and LiLyGo? At the moment this does not appear to be the case based on the state of official documentation and the closure of the official site of Kendryte, the maker of the K210.

Currently, I advise you instead to turn to an M5stack box and the OV2640 camera module compatible with all the examples offered for ESP32-CAM modules.

Comparison of models

Here is a comparative table of the main technical characteristics

T-Watch TOUCHT-Watch 2020T-Block
Version2019V1V2
ProcessorESP32-DOWDQ6ESP32-DOWDQ6ESP32-DOWDQ6
Flash16MB16MB16MB
SPRAM8MB8MB8MB
USB / TTL converter for programmingCP2104CP2104CP2104
Accessories
User button36NoNo36
SD card readerAdditional cardNoYesNot available
Power controllerAXP202AXP202AXP202AXP202
GPSAdditional cardAir 530Not available
AccelerometerBMA423

3-axis

BMA423

3-axis

BMA423

3-axis

MPU6050

6 axes

RTC clockPCF8563PCF8563PCF8563PCF8563
Vibrator (motor)334?33
External I2C bus (SDA / SCL)21/2221/2221/2221/22
I2S audio interface

(BCK / WS / DOUT)

26/25/33
IR (send only)134
Extension connector *

Molex 53015-0410

x1NoNo
ScreenST7789V

TFT

ST7789V

TFT

ST7789V

TFT

e-Paper
Screen resolution (HxV)240×240240×240240×240240×240
TouchscreenFT5206FT6236FT6236
Camera
Interruptions
AXP202 35353535
Power button37373737
Accelerometer39393939
Touchscreen38383838
Other interfaces
UART (TX/RX)33/3433/34
Useful links
Pin definition fileGitHubGitHubGitHubGitHub
Pin identificationSeeSeeSee
ExamplesSeeSee

(*) requires a cable fitted with a Molex 51065-0400 connector

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