PineTime

Specifications

Dimensions: 37.5 x 40 x 11mm
Weight: 38 grams
IP Rating: IP67 (waterproof to 1 meter)
Display:

Size: 1.3 inches (33mm) diagonal

Type: IPS capacitive touchscreen, RGB 65K colors

Resolution: 240x240 pixels

System on Chip: Nordic Semiconductor nRF52832
Flash: 512KB with additional 4MB SPI NOR
RAM: 64KB
Bluetooth: 5.0 (including Bluetooth Low Energy)
Sensors: Accelerometer, Heart rate sensor
Feedback: Vibration motor
Battery: 170-180mAh LiPo

SWD Pinout

The devkits have exposed SWD pins for flashing and debugging. The pinout is:

Driving the peripherals

Display

Note: The factory-default software on the PineTime does not auto-detect the display being disconnected when it has already booted. That can cause garbled output, to fix it just restart the PineTime.

The display is driven using the ST7789 display controller. Use the following pins to drive the screen:

PineTime pin	ST7789 pin
LCD_SCK (P0.02)	SPI clock
LCD_SDI (P0.03)	SPI MOSI
LCD_RS (P0.18)	Clock/data pin (CD)
LCD_CS (P0.25)	Chip select
LCD_RESET (P0.26)	Display reset
LCD_BACKLIGHT_{LOW,MID,HIGH}	Backlight (active low)

Notes:

• Chip select must be held low while driving the display. It must be high when using other SPI devices on the same bus (such as external flash storage) so that the display controller won't respond to the wrong commands.
• SPI must be used in mode 3. Mode 0 (the default) won't work.
• LCD_DISPLAY_* is used to enable the backlight. Set at least one to low to see anything on the screen.
• Use SPI at 8MHz (the fastest clock available on the nRF52832) because otherwise refreshing will be super slow.

Battery

Reading whether the PineTime has power attached is easy: simply read the charge indication pin (P0.12). When it is high it is running on battery, when it is low it is charging.

Reading the battery voltage is a bit harder. For that you can use the battery voltage pin on P0.31 (AIN7). The returned value is 12 bits, which means it is 0..4095. You can get the measured voltage with the following formula, assuming a reference voltage of 3.3V (this is configurable in the ADC):

adcVoltage = adcValue / (4095 / 3.3)

The measured voltage is actually half of the actual battery voltage, because the ADC is connected between a voltage divider where both resistors are 1MΩ. This can be corrected by multiplying the value:

batteryVoltage = adcValue * 2 / (4095 / 3.3)

It's often better to avoid floating point values on embedded systems and in this case there is no reason to use float at all, we can just represent the value in millivolts. Therefore the formula can be simplified to:

batteryVoltage = adcValue * 2000 / (4095 / 3.3)
batteryVoltage = adcValue * 2000 / 1241

Converting this voltage to an estimated capacity in percent requires a more complicated algorithm, because Lithium-ion batteries have a non-linear discharge curve.

Manual / Articles

• Beginner manual explained how you to programs and install zephyr on PineTime Dev Kit, big thanks to najnesnaj :-)

• Sneak Peek of PineTime Smart Watch… And why it’s perfect for teaching IoT

Development efforts

	Project Homepage	Project Source	PineTime Implementations
FreeRTOS	https://www.freertos.org	https://sourceforge.net/projects/freertos/	JF002/Pinetime kaythe/pinetime-os
Zephyr	https://www.zephyrproject.org	https://github.com/zephyrproject-rtos/zephyr	najnesnaj/pinetime-zephyr SuperPrower/pinetime_zephyr_sample_fw
mynewt	https://mynewt.apache.org/about/	https://github.com/apache/mynewt-core	lupyuen/stm32bluepill-mynewt-sensor
MbedOS	https://os.mbed.com	https://github.com/ARMmbed/mbed-os	sethitow/mbed-pinetime
TinyGo	https://tinygo.org	https://github.com/tinygo-org/tinygo	aykevl/go-smartwatch

Datasheets and Schematics

Schematics

• PineTime Schematic ver1.0a
• PineTime GPIO Port Assignment ver1.0

Component Datasheets

• NORDIC SoC information:
  • NORDIC nRF52832 Product Brief
  • NORDIC nRF52840 Product Brief
• PMU (Power Management Unit) information:
  • SGMicro SGM40561 Single Cell Charger Datasheet
  • SGMicro SGM2036 3.3V Low Power Low Dropout RF Linear Regulator Datasheet
• SPI Flash information:
  • Macronix 64Mb(8MB) SPI NOR Flash
  • Macronix 128Mb(16MB) SPI NOR Flash
• LCD Panel:
  • 1.3" 240x240 IPS LCD Panel Specification for PineTime
  • 11.6" Sitronix LCD Driver/Controller Datasheet
• Touchpad information:
  • Touchpad Specification for PineTimel
  • 11.6" Hynitron CST816S Capacitive Touch Controller Datasheet in Chinese
    • English Translation
• Sensor:
  • BOSCH BMA421 Triaxial VAcceleration Sensor Product Brief
  • TianYiHeXin HRS3300 PPG Heart Rate Sensor Data Sheet