# XD84
Development docs covering the following:
- Kimera core
- RGB
- Backlight
- Light Through Cat
## Kimera core
What little available info that was available for the qmk port
- atmega32u4 16Mhz
- board seems to have a 6Mhz crystal
- 2x PCA9555 I2C IO expander
Links:
- [Schematic, BOM, Gerbers](/kairyu/kimera/blob/master/kimera_core)
- [Original firmware](https://github.com/kairyu/tmk_keyboard_custom/tree/master/keyboard/kimera)
```c
/*
Kimera_core_v1.0 Components
U1 (atmega32u4)
,----------------.
TX --| TX0(PD3) RAW |--
RX --| RX1(PD2) GND |--
--| GND RESET |-- RST
--| GND VCC |--
SDA --| 2(PD1) (PF4)A3 |--
SCL --| 3(PD0) (PF5)A2 |--
(INT) --| 4(PD4) (PF6)A1 |--
--| 5(PC6) (PF7)A0 |--
--| 6(PD7) (PB1)15 |-- SCK
LED2 --| 7(PE6) (PB3)14 |-- MISO
LED1 --| 8(PB4) (PB2)16 |-- MOSI
LED3 --| 9(PB5) (PB6)10 |-- LED4
`----------------'
IC1 (PCA9555) IC2 (PCA9555)
,----------. ,----------.
SDA --| SDA P00 |-- P1 SDA --| SDA P00 |-- P17
SCL --| SCL P01 |-- P2 SCL --| SCL P01 |-- P18
INT --| INT P02 |-- P3 INT --| INT P02 |-- P19
| P03 |-- P4 | P03 |-- P20
GND --| A0 P04 |-- P5 VCC --| A0 P04 |-- P21
SJ1 --| A1 P05 |-- P6 SJ1 --| A1 P05 |-- P22
SJ2 --| A2 P06 |-- P7 SJ2 --| A2 P06 |-- P23
| P07 |-- P8 | P07 |-- P24
| | | |
| P10 |-- P9 | P10 |-- P25
| P11 |-- P10 | P11 |-- P26
| P12 |-- P11 | P12 |-- P27
| P13 |-- P12 | P13 |-- P28
| P14 |-- P13 | P14 |-- P29
| P15 |-- P14 | P15 |-- P30
| P16 |-- P15 | P16 |-- P31
| P17 |-- P16 | P17 |-- P32
`----------' `----------'
*/
```
### Bootloader
Default bootloader is `atmel-dfu`.
Reboot to bootloader via magnetic switch next to icsp header.
Flash using regular dfu methods.
### XD84 pin mappings
Taken from [kimera-config.json](https://github.com/kairyu/tkg/blob/master/keyboard/config/kimera-config.json)
"row_mapping": [ 1, 2, 3, 4, 5, 6 ],
"col_mapping": [ 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 ],
# RGB
- PIN C7
- Number of RGB LED 7
# Backlight
- PIN B6
# Light Through Cat
TODO - PWM C6
## Assumptions
### Pin/Port mappings
- All cols are on the same IC
- All rows are on the same IC and port
- Pins mapped sequentially
- Each port only does row or column not a mixture of both
- No need to have complex port config
-
| 0 | 1 | IC1 Port 0 pin 0 |
| 1 | 2 | IC1 Port 0 pin 1 |
| 2 | 3 | IC1 Port 0 pin 2 |
| 3 | 4 | IC1 Port 0 pin 3 |
| 4 | 5 | IC1 Port 0 pin 4 |
| 5 | 6 | IC1 Port 0 pin 5 |
- Safe enough to assume `row_index == pin`
| 0 | 17 | IC2 Port 0 pin 0 |
| 1 | 18 | IC2 Port 0 pin 1 |
| 2 | 19 | IC2 Port 0 pin 2 |
| 3 | 20 | IC2 Port 0 pin 3 |
| 4 | 21 | IC2 Port 0 pin 4 |
| 5 | 22 | IC2 Port 0 pin 5 |
| 6 | 23 | IC2 Port 0 pin 6 |
| 7 | 24 | IC2 Port 0 pin 7 |
| 8 | 25 | IC2 Port 1 pin 0 |
| 9 | 26 | IC2 Port 1 pin 1 |
| 10 | 27 | IC2 Port 1 pin 2 |
| 11 | 28 | IC2 Port 1 pin 3 |
| 12 | 29 | IC2 Port 1 pin 4 |
| 13 | 30 | IC2 Port 1 pin 5 |
| 14 | 31 | IC2 Port 1 pin 6 |
- Safe enough to assume here col_index does not need to be converted to pin
- Reading both ports one after the other gives us the same sequential behavior
- maps to the usual practice of reading matrix columns
- while this technically gives 16 column reads, the 16th column can never be set so is safely ignored
## Notes
[pca9555 datasheet](https://www.ti.com/lit/ds/symlink/pca9555.pdf)
- Other Kimera based boards with non sequential pin mappings, pins mapped across ICs, or mixed row/col configs will need more complicated `pin -> i2c_addr,port,pin` logic as well as rather more complex pin functions.
## Return to stock firmware
Not tested but original firmware seems to be available in the [kairyu/tkg-firmware](https://github.com/kairyu/tkg-firmware/blob/master/kimera-core.hex) repo.