The T28 is a nRF52832 based smart watch with onboard GPS, Barometer, Accelerometer and optical HRM (PPG). The T28 is available from several online retailers under a variety of brand names; Mindkoo/LEMDIOE/DOITOP/NIYOQUE to name a few.
This board is supported by Sandeep Mistry's nRF5 core, through the following smartwatch variant T28 variant.h.
| peripheral type | name | pin | T28 |
|---|---|---|---|
| accelerometer | Kx023 | SCL | 16 |
| SDA | 13 | ||
| optical HR sensor | Si1143? | SCL | ? |
| SDA | ? | ||
| INT | ? | ||
| LED | 9 | ||
| OLED Character ROM | GT24L24A2Y | MISO | 19 |
| MOSI | 23 | ||
| SCK | 22 | ||
| CE | 21 | ||
| OLED | --- | MISO | n/a |
| --- | MOSI | 18 | |
| --- | SCK | 17 | |
| --- | RST | 14 | |
| --- | CS | 28 | |
| --- | DC | 30 | |
| --- | VPP | 1 | |
| GPS | G7020-KT | Tx | 31 |
| (ublox) | Rx | 11 | |
| Altitude/Pressure/Temp | HP203B | SCL | ? |
| SDA | ? | ||
| side tactile button | (top) | BUTTON1 | 20 |
| side tactile button | (bottom) | BUTTON2 | 24 |
| capacitive touch button | RH6015C | BUTTON3 | 2 |
| vibrate motor | --- | VIBRATE -or- | 10 |
| LED_BUILTIN | |||
| serial UART * | --- | Tx | 26 |
| Rx | 25 | ||
| battery voltage level | --- | --- | ? |
* There are no dedicated UART pins broken out. I chose two solder pads near the OLED connector as Tx,Rx.
- 0x1F : Accelerometer (Kx022/Kx023)
- 0x5A : Heart Rate Sensor / PPG (Si1143)
- 0x76 : Altitude / Pressure / Temperature (HP203B)
