Turning Technologies QT "clicker" (RCQR-01) hardware and software exploration (WIP). My adventures in reverse engineering an interesting platform.
- based on nrf51822 (QFAA, 16kB ram, 256kB flash, Cortex M0)
- low ram (non 32k model) makes it very tricky to run any BLE softdevice.
- lcd 360x160 ?, 2-bit grayscale ?
- maybe ST7586 chipset? connected to serial bus. Use SPI to transfer data to chip.
- hacked up uGFX framework
- extremely wierd pixel column format (packed 3 2-bit pixels per byte)
- no per-pixel modification, so using a 1bpp framebuffer (consumes considerable amount of ram) and just flushing periodically to display chip
- may be able to optimize this down to a smaller row buffer, and for pixel-level or window modifications, just read and rewrite and "dirty" display lines
- Microchip MCP1256 3.3v boost converter/regulator powers lcd stuff
- CAT25512 512-Kb SPI Serial CMOS EEPROM
- 8x8 matrix, qwerty style. Glow-in-the-dark keypad is a neat touch.
- rows have external pullups?
| nRF51822 gpio | component | nRF51822 gpio | component | |
|---|---|---|---|---|
| 00 | EEP_CK | 16 | EEP_SO | |
| 01 | LCD_CS | 17 | KEY_COL3 | |
| 02 | LCD_RST | 18 | KEY_ROW1 | |
| 03 | LCD_DC | 19 | KEY_ROW2 | |
| 04 | LCD_MISO | 20 | KEY_ROW3 | |
| 05 | LCD_MOSI | 21 | KEY_ROW4 | |
| 06 | LCD_RW | 22 | KEY_ROW5 | |
| 07 | LCD_SCK | 23 | KEY_ROW6 | |
| 08 | KEY_ROW0 | 24 | KEY_ROW7 | |
| 09 | KEY_COL0 | 25 | KEY_COL4 | |
| 10 | KEY_COL1 | 26 | KEY_COL5 | |
| 11 | KEY_COL2 | 27 | MCP1256_SHDN | |
| 12 | EEP_CS | 28 | KEY_COL6 | |
| 13 | LCD_BACKLIGHT | 29 | KEY_COL7 | |
| 14 | MCP1256_PGOOD | 30 | EEP_SI | |
| 15 | MCP1256_SLEEP |
see picture below
- unpopulated cortex debug connector pad - only vcc, gnd, swdio, swdclk populated
- test points pad pinout (from left to right - ignore the pins with the larger holes)
| pad | destination |
|---|---|
| 1 | SWDIO/nRST |
| 2 | SWDCLK |
| 3 | EEP_SO |
| 4 | EEP_SI |
| 5 | EEP_CLK |
| 6 | EEP_CS |
| 7 | P0.20 ? |
| 8 | P0.19 ? |
| 9 | GND |
| 10 | VCC 3V3 |
- using free, cross-platform Segger Studio (only tested on mac as of yet, linux testing to come)
- using segger j-link for swd programming and debugging
- setup path to the nrf51 sdk. Mine is
NRF_SDK_DIR=../../nRF5_SDK_12.3.0as project macro (set on common configuration).- note below about needing to make two minor patches to sdk
- display/ui framework is uGFX
- (maybe)implement display row-level buffering instead of huge frambuffer to save ram and draw/refresh time.
- improve standby/sleep modes and decrease current draw. Currently get avg <1mA when display sleeping, which is good enough for me. (The 1ms timer tick is wasteful - maybe move to 10ms?)
- uGFX offers menuing framework, look into implementing this
- nrf51822 product specification datasheet
- nrf51 reference manual
- nordic nrf51 sdk 12.3.0
- sdk bug needs patching: nrf_esb_rf_channel_get -> nrf_esb_get_rf_channel in nrf_esb.h
- modify app_timer.c to use SWI3 instead of SWI0, which is already used by nrf_esb.c
#define SWI_IRQn SWI3_IRQn
#define SWI_IRQHandler SWI3_IRQHandler