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

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

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.

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.

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 The e-paper screen has been replaced by a color TFT screen of 1.54 “diagonal available in a touch version or not called T-Watch-N sold in a yellow packaging.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

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):

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.

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.

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.

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.

Function T-Watch 2020 V1 T-Watch 2020 V2
ESP32 ESP32-DOWDQ6 ESP32-DOWDQ6
Flash 16MB 16MB
SPRAM 8MB 8MB
Touchscreen resolution 1.54 “ 240×240 240×240
Touch screen driver FT6236 FT6236
TFT screen driver ST7789 ST7789
GPS module Air530

Powered by LDO4 port

User button Rotary + Click Rotary + Click (?)
Micro-USB connector Protected by a removable hood x1 (?)
Drums LiPo 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.

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 TOUCH T-Watch 2020 T-Block
Version 2019 V1 V2
Processor ESP32-DOWDQ6 ESP32-DOWDQ6 ESP32-DOWDQ6
Flash 16MB 16MB 16MB
SPRAM 8MB 8MB 8MB
USB / TTL converter for programming CP2104 CP2104 CP2104
Accessories
User button 36 No No 36
SD card reader Additional card No Yes Not available
Power controller AXP202 AXP202 AXP202 AXP202
GPS Additional card Air 530 Not available
Accelerometer BMA423

3-axis

BMA423

3-axis

BMA423

3-axis

MPU6050

6 axes

RTC clock PCF8563 PCF8563 PCF8563 PCF8563
Vibrator (motor) 33 4 ? 33
External I2C bus (SDA / SCL) 21/22 21/22 21/22 21/22
I2S audio interface

(BCK / WS / DOUT)

26/25/33
IR (send only) 13 4
Extension connector *

Molex 53015-0410

x1 No No
Screen ST7789V

TFT

ST7789V

TFT

ST7789V

TFT

e-Paper
Screen resolution (HxV) 240×240 240×240 240×240 240×240
Touchscreen FT5206 FT6236 FT6236
Camera
Interruptions
AXP202  35 35 35 35
Power button 37 37 37 37
Accelerometer 39 39 39 39
Touchscreen 38 38 38 38
Other interfaces
UART (TX/RX) 33/34 33/34
Useful links
Pin definition file GitHub GitHub GitHub GitHub
Pin identification See See See
Examples See See

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

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