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The PineTime

The PineTime is a free and open source smartwatch capable of running custom-built open operating systems. Some of the notable features include a heart rate monitor, a week-long battery, and a capacitive touch IPS display that is legible in direct sunlight. It is a fully community driven side-project which anyone can contribute to, allowing you to keep control of your device.

Getting started

Read these first!

The frequently asked question can be found in the article PineTime FAQ.

Default OS

The current default operating system on the PineTime is called InfiniTime, you can find more information about the firmware on its GitHub page. First devkits shipped with a proprietary custom firmware.

You can find a list of available firmware and other software here: PineTime Development

Companion Apps

PineTime/InfiniTime needs a companion app to e.g. upload a firmware, get notifications from a phone, or just get the date/time. Here are some companion apps:

  • Gadgetbridge (Android >= 4.4) - Companion mobile app, supports updating firmware/bootloader, send notifications, etc.
  • Amazfish (SailfishOS and Linux) - Companion mobile and desktop app, supports updating firmware/bootloader, send notifications, etc.
  • Siglo (Linux) - Companion desktop app.
  • PinetimeFlasher (Windows) - Companion desktop app, only supports flashing firmware.
  • nRFConnect (iOS) - Only supports flashing firmware. The app is closed source and versions after 4.24.3 don't work for the PineTime anymore
  • InfiniLink (iOS) - Companion mobile app in development. Supports updating firmware/bootloader, setting date and time, Apple Music controls, and battery and heart rate data.
  • ITD (Linux)


  • Dimensions: 37.5 x 40 x 11mm
  • Weight: 38 grams
  • IP Rating: IP67 (waterproof to 1 meter (sealed edition!))
  • Display:
    • Size: 1.3 inches (33mm) diagonal
    • Type: IPS capacitive touchscreen, RGB 65K colors
    • Display Controller: ST7789
    • 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 3.8V LiPo




Developers and coding:

Development efforts

To read more about development on the PineTime, the projects available and more technical details, check out PineTime Development

Useful articles and blog posts

If you want to dive in to the ecosystem, here's a short list of various articles and blog posts that can help you set up your soft- or hardware development environment.



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_RS (P0.18) Command/Data pin (CD)
LCD_CS (P0.25) Chip select
LCD_RESET (P0.26) Display reset
LCD_BACKLIGHT_{LOW,MID,HIGH} Backlight (active low)


  • 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_BACKLIGHT_* 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.


Adafruit ST7789 driver in cpp

Battery measurement

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.


The button on the side of the PineTime is disabled by default. To enable it, drive the button out pin (P0.15) high.

While enabled, the button in pin (P0.13) will be high when the button is pressed, and low when it is not pressed.

Note that the button consumes around 34µA when P0.15 is left high. To reduce current consumption, set it to low most of the time and only set it to high shortly before reading it. The button needs a short time to give good outputs though, setting P0.15 high at least four times in a row seems to result in enough delay that P0.13 has a stable output.

Touch panel

The touch panel is controlled by a Hynitron CST816S chips. Unfortunately, there is not much information about this chip on the internet apart from the datasheet below and a reference driver. This is enough to implement a basic driver, but crucial information needed to implement advanced functionalities are missing (I²C protocol and registers, timings, power modes,...).


  • P0.10 : Reset
  • P0.28 : Interrupt (signal to the CPU when a touch event is detected)
  • P0.06 : I²C SDA
  • P0.07 : I²C SCL


  • Device address : 0x15
  • Frequency : from 10Khz to 400Khz

NOTE: The controller goes to sleep when no event is detected. In sleep mode, the controller does not communicate on the I²C bus (it appears disconnected). So, for the communication to work, you need to tap on the screen so that the chip wakes-up.

NOTE: The I²C bus, also known as TWI bus, has known issues, make sure to write your TWI driver with timeouts.

Touch events

Touch information is available from the 63 first registers of the controller. Remember: the device is in sleep mode when no touch event is detected. It means that you can read the register only when the touch controller detected an event. You can use the Interrupt pin to detect such event in the software.

These 63 bytes contain up to 10 touch point (X, Y, event type, pressure,...) :

Byte Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
0 ?
1 GestureID : (Gesture code ,

0x00: no gesture,

0x01: Slide down,

0x02: Slide up,

0x03: Slide left,

0x04: Slide right,

0x05: Single click,

0x0B: Double click,

0x0C: Long press)

2 ? Number of touch points
3 Event (0 = Down, 1 = Up, 2 = Contact) ? X (MSB) coordinate
4 X (LSB) coordinate
5 ? Touch ID Y (MSB) coordinate
6 Y (LSB) coordinate
7 Pressure (?)
8 Miscellaneous (?)

Bytes 3 to 8 are repeated 10 times (10*6 + 3 = 63 bytes).


  • The touch controller seems to report only 1 touch point
  • Fields X, Y, Number of touch points and touch ID are updated. The others are always 0.


The reference driver specifies some registers and value, but there is no information about them:

Register Address Description
HYN_REG_POWER_MODE 0xA5 0x03 = SLEEP (reset the touchpanel using the reset pin before using this register : pin_low, delay 5ms, pin_high, delay 50ms then write 3 to register 0xA5)

WARNING : Writing the SLEEP command (write 0x05 in HYN_REG_POWER_MODE) seems to freeze the controller (it returns only static values) until the battery is totally drained and the whole system reset. Analysis and debugging is more than welcome!


The on board accelerometer in devices shipped before July 2021 is a Bosch BMA421, connected to the I2C bus. Devices shipped after July 2021 use a Bosch BMA425 accelerometer.


  • P0.06 : I²C SDA
  • P0.07 : I²C SCL
  • P0.08 : Interrupt

I2C Device address : 0x18

Reducing power consumption

The PineTime appears to be able to sleep with a current consumption of only 66µA.

To investigate current consumption, it's a good idea to disable everything possible to get the lowest current consumption possible, and then re-enable things one by one. Here is one way to get a baseline current consumption of 60µA, as measured from the 3.3V pin with the battery disconnected:

  • Enable the DC/DC regulator. This doesn't affect the current consumption while sleeping, but almost halves the runtime current consumption.
  • Use the low-frequency (32.768kHz) oscillator.
  • Leave all pins in their default state, except for P0.05 (SPI CS) and P0.25 (LCD CS) which should be configured as an output and set to high.
  • Put the heart rate sensor in sleep mode by setting the PDRIVER (0x0C) register to 0, see the HRS3300 datasheet for details.
  • Put the SPI flash in deep power-down mode by setting flash CS high, then low, then writing the byte 0xb9 on the SPI bus, and then setting flash CS high again.
  • Sleep in a loop, using WFE or WFI (if you're using the Nordic SoftDevice, call sd_app_evt_wait instead).

Here are some current consumption statistics (current consumed in addition to the baseline power), roughly ordered from large to small:

Source Current Notes
SWD 3.05mA Power cycle the chip after programming to avoid this, it can hide other inefficiencies.
LCD 5.61mA Set the LCD to sleep mode when not used, using SLPIN.
Backlight high 12.27mA
Backlight mid 5.51mA
Backlight low 1.83mA
ADC left enabled 1.3mA Stopping SAADC brings the current back to the baseline. It seems that it doesn't need to be disabled entirely.
UART left enabled 1.25mA Some bootloaders might leave the UART enabled after they start the application, leading to high current consumption.
Edge triggered pin interrupts 0-0.47mA? It appears that under some configurations, edge triggered interrupts result in a large power drain. One way to avoid this is by using the pin sense mechanism.
Accelerometer 0.15mA 151µA in performance mode, 99µA with performance mode disabled but power saving disabled, 50µA while polling on a high interval (100Hz, average 4 samples), 14µA when running at the lowest possible setting that still counts steps (50Hz, no averaging).
HRS sensor is enabled 0.1mA The HRS3300 sensor is enabled on power on. Write byte 0x00 to the PDRIVER register (0x0C) to set it in sleep mode.
BUTTON_OUT left high 0.04mA See Button for how to avoid this.
SPI flash sleep mode 0.014mA Sleep mode still consumes power. Put it in deep power down mode to avoid this.
SPI, I2C (negligible) SPI and I2C appear to consume very little power when idle, around 1µA or less.


The following accessory is compatible with the PineTime.

Watch band

The PineTime uses a standard 20mm watch band / strap. There is a thread in the forum discussing this.

Due to the watches design. Retention for the spring bars are recessed into the watch. Not all 20mm bands / straps work. This is especially the case for Nato style bands / straps being too thick.

Known working bands:


There are no cases for PineTime yet, but some cases for Fitbit are suitable for it. Cases for Fitbit have one microphone hole, which is unnecessary for the PineTime, but otherwise they fit perfectly.

The community designed the following cases:

Datasheets, Schematics and Certifications


Note: The part number for the SPI FLASH in the schematic diagram is not correct, the PineTime features a larger external FLASH device, see below.

Chip Datasheets

NORDIC nRF52832 information:

ARMv7-M information:

Component Datasheets

PMU (Power Management Unit) information:

SPI Flash information:

LCD Panel:

Touchpad information: