Smartwatch

Official website: https://wiki.pine64.org/index.php/PineTime

This repo is just my sandbox for playing around with PineTime firmware. These notes are only tested on Ubuntu 18.04.3 LTS

Compiling notes

• sudo apt install gcc-arm-none-eabi
• Download the nRF5 SDK v16.0 and extract it somewhere. Set $NRF_SDK to that path.
• Update the cross-compiler paths and version in $NRF_SDK/components/toolchain/gcc/Makefile.posix :

GNU_INSTALL_ROOT ?= /usr/bin
GNU_VERSION ?= 6.3.1
GNU_PREFIX ?= arm-none-eabi

Using the SDK

Looks like the SDK wants the custom board to be called custom_board.h and then needs to see #define BOARD_CUSTOM

Flashing notes

initial unprotect + erase

from https://forum.pine64.org/showthread.php?tid=8143

source [find interface/cmsis-dap.cfg]
source [find target/nrf52.cfg]

init
nrf52.dap apreg 1 0x04 0x01
sleep 100
shutdown

Schematic notes

(Just a few random notes recorded when parsing the schematic and datasheets.)

SoC + flash

nRF52832

• ARM Cortex-M4F
• crystals: 32.768 kHz and 32 MHz
• external SPI flash: PM25LV512
  • 64 Kbyte (512 Kbit)
  • 256 byte pages, 4 Kbyte sectors, 32 Kbyte blocks
  • 2ms page program, 60ms sector erase
  • 200,000 program/erase cycles per sector

Power scheme

Single-cell LiPo. Charge cradle powered by USB (5 VDC) feeds +5V through two parallel Schottkey diodes into the charge IC. Battery powers two LDO's which power everything except the vibration motor and heart-rate sensor.

• charger IC: SGM40561
• VCC33 (main LDO): ME6206
• VDD33 (low-noise sensor LDO): SGM2036-3.3

Sensors

• accelerometer: Bosch BMA421
• touch sensor (not populated?): tontek TTP233D-QA6

LCD

• connected via SPI