QMK firmware for Toshiba T1200

keyboard.json

{
  "keyboard_name": "toshiba_t1200",
  "manufacturer": "Toshiba",
  "url": "",
  "maintainer": "penk",
  "usb": {
    "vid": "0xFEED",
    "pid": "0x0000",
    "device_version": "1.0"
  },
  "processor": "RP2040",
  "bootloader": "rp2040",
  "layouts": {
    "LAYOUT": {
      "layout": [
        {"matrix": [0, 0], "label":"F1", "x":0, "y":0}, {"matrix": [0, 1], "label":"Num Lock", "x":1, "y":0}, {"matrix": [0, 2], "label":"F3", "x":2, "y":0}, {"matrix": [0, 3], "label":"PgDn", "x":3, "y":0}, {"matrix": [0, 4], "label":"F5", "x":4, "y":0}, {"matrix": [0, 5], "label":"F7", "x":5, "y":0}, {"matrix": [0, 6], "label":"F9", "x":6, "y":0}, {"matrix": [0, 7], "label":"End", "x":7, "y":0},
        {"matrix": [1, 0], "label":"F2", "x":0, "y":1}, {"matrix": [1, 1], "label":"Scroll Lock", "x":1, "y":1}, {"matrix": [1, 2], "label":"F4", "x":2, "y":1}, {"matrix": [1, 3], "label":"PgUp", "x":3, "y":1}, {"matrix": [1, 4], "label":"F6", "x":4, "y":1}, {"matrix": [1, 5], "label":"F8", "x":5, "y":1}, {"matrix": [1, 6], "label":"F10", "x":6, "y":1}, {"matrix": [1, 7], "label":"Alt", "x":7, "y":1},
        {"matrix": [2, 0], "label":"Esc", "x":0, "y":2}, {"matrix": [2, 1], "label":"1", "x":1, "y":2}, {"matrix": [2, 2], "label":"Tab", "x":2, "y":2}, {"matrix": [2, 3], "label":"Q", "x":3, "y":2}, {"matrix": [2, 4], "label":"A", "x":4, "y":2}, {"matrix": [2, 5], "label":"Ctrl", "x":5, "y":2}, {"matrix": [2, 6], "label":"Shift", "x":6, "y":2}, {"matrix": [2, 7], "label":"\\", "x":7, "y":2},
        {"matrix": [3, 0], "label":"2", "x":0, "y":3}, {"matrix": [3, 1], "label":"3", "x":1, "y":3}, {"matrix": [3, 2], "label":"W", "x":2, "y":3}, {"matrix": [3, 3], "label":"E", "x":3, "y":3}, {"matrix": [3, 4], "label":"S", "x":4, "y":3}, {"matrix": [3, 5], "label":"D", "x":5, "y":3}, {"matrix": [3, 6], "label":"Z", "x":6, "y":3}, {"matrix": [3, 7], "label":"X", "x":7, "y":3},
        {"matrix": [4, 0], "label":"4", "x":0, "y":4}, {"matrix": [4, 1], "label":"5", "x":1, "y":4}, {"matrix": [4, 2], "label":"R", "x":2, "y":4}, {"matrix": [4, 3], "label":"T", "x":3, "y":4}, {"matrix": [4, 4], "label":"F", "x":4, "y":4}, {"matrix": [4, 5], "label":"G", "x":5, "y":4}, {"matrix": [4, 6], "label":"V", "x":6, "y":4}, {"matrix": [4, 7], "label":"C", "x":7, "y":4},
        {"matrix": [5, 0], "label":"6", "x":0, "y":5}, {"matrix": [5, 1], "label":"7", "x":1, "y":5}, {"matrix": [5, 2], "label":"Y", "x":2, "y":5}, {"matrix": [5, 3], "label":"U", "x":3, "y":5}, {"matrix": [5, 4], "label":"H", "x":4, "y":5}, {"matrix": [5, 5], "label":"B", "x":5, "y":5}, {"matrix": [5, 6], "label":"N", "x":6, "y":5}, {"matrix": [5, 7], "label":"Space", "x":7, "y":5},
        {"matrix": [6, 0], "label":"8", "x":0, "y":6}, {"matrix": [6, 1], "label":"9", "x":1, "y":6}, {"matrix": [6, 2], "label":"I", "x":2, "y":6}, {"matrix": [6, 3], "label":"O", "x":3, "y":6}, {"matrix": [6, 4], "label":"J", "x":4, "y":6}, {"matrix": [6, 5], "label":"K", "x":5, "y":6}, {"matrix": [6, 6], "label":",", "x":6, "y":6}, {"matrix": [6, 7], "label":"M", "x":7, "y":6},
        {"matrix": [7, 0], "label":"0", "x":0, "y":7}, {"matrix": [7, 1], "label":"-", "x":1, "y":7}, {"matrix": [7, 2], "label":"P", "x":2, "y":7}, {"matrix": [7, 3], "label":"Left", "x":3, "y":7}, {"matrix": [7, 4], "label":"L", "x":4, "y":7}, {"matrix": [7, 5], "label":";", "x":5, "y":7}, {"matrix": [7, 6], "label":".", "x":6, "y":7}, {"matrix": [7, 7], "label":"Delete", "x":7, "y":7},
        {"matrix": [8, 0], "label":"=", "x":0, "y":8}, {"matrix": [8, 1], "label":"Up", "x":1, "y":8}, {"matrix": [8, 2], "label":"[", "x":2, "y":8}, {"matrix": [8, 3], "label":"]", "x":3, "y":8}, {"matrix": [8, 4], "label":"Right", "x":4, "y":8}, {"matrix": [8, 5], "label":"'", "x":5, "y":8}, {"matrix": [8, 6], "label":"/", "x":6, "y":8}, {"matrix": [8, 7], "label":"Caps Lock", "x":7, "y":8},
        {"matrix": [9, 0], "label":"Backspace", "x":0, "y":9}, {"matrix": [9, 1], "label":"Down", "x":1, "y":9}, {"matrix": [9, 2], "label":"Home", "x":2, "y":9}, {"matrix": [9, 3], "label":"Enter", "x":3, "y":9}, {"matrix": [9, 4], "label":"`", "x":4, "y":9}, {"matrix": [9, 5], "label":"Right Shift", "x":5, "y":9}, {"matrix": [9, 6], "label":"Print Screen", "x":6, "y":9}, {"matrix": [9, 7], "label":"Insert", "x":7, "y":9},
        {"matrix": [10, 0], "label":"GUI", "x":0, "y":10}, {"matrix": [10, 1], "label":"Fn", "x":1, "y":10}
      ]
    }
  },
  "matrix_pins": {
    "rows": ["GP0", "GP9", "GP1", "GP2", "GP10", "GP3", "GP11", "GP12", "GP5", "GP29", "GP6"],
    "cols": ["GP28", "GP7", "GP27", "GP8", "GP4", "GP15", "GP14", "GP13"]
  },
  "diode_direction": "COL2ROW"
}

keymap.c

#include QMK_KEYBOARD_H

enum layer_names {
    _BASE,
    _FN
};

const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
    [_BASE] = LAYOUT(
        KC_F1,   KC_LNUM, KC_F3,   KC_PGDN, KC_F5,   KC_F7,   KC_F9,   KC_END,
        KC_F2,   KC_LSCR, KC_F4,   KC_PGUP, KC_F6,   KC_F8,   KC_F10,  KC_LALT,
        KC_ESC,  KC_1,    KC_TAB,  KC_Q,    KC_A,    KC_LCTL, KC_LSFT, KC_BSLS,
        KC_2,    KC_3,    KC_W,    KC_E,    KC_S,    KC_D,    KC_Z,    KC_X,
        KC_4,    KC_5,    KC_R,    KC_T,    KC_F,    KC_G,    KC_V,    KC_C,
        KC_6,    KC_7,    KC_Y,    KC_U,    KC_H,    KC_B,    KC_N,    KC_SPC,
        KC_8,    KC_9,    KC_I,    KC_O,    KC_J,    KC_K,    KC_COMM, KC_M,
        KC_0,    KC_MINS, KC_P,    KC_LEFT, KC_L,    KC_SCLN, KC_DOT,  KC_DEL,
        KC_EQL,  KC_UP,   KC_LBRC, KC_RBRC, KC_RGHT, KC_QUOT, KC_SLSH, KC_CAPS,
        KC_BSPC, KC_DOWN, KC_HOME, KC_ENT,  KC_GRV,  KC_RSFT, KC_PSCR, KC_INS,
        MO(_FN), KC_LGUI
    ),
    [_FN] = LAYOUT(
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______, _______, _______, _______, _______, _______, _______,
        _______, _______
    )
};

I used @thedalles77's awesome T4p1_thruhole PCB and a 22-pin 1.25mm pitch FFC connector. Too impatient to wait for the Teensy 4.1 order to arrive, I used that board as a breakout, slapped on an RP2040 Zero, and translated the Arduino code to QMK firmware.

Here's how I connected the RP2040 Zero:

0     1     2     3     4     5     6     7     8     9      10      11
GP9   x     GP10  GP11  GP12  GP29  GP28  GP27  x     GP15   GP14    GP13

23    22    21    20    19    18    17    16    15    14
GP0   GP1   GP2   GP3   x     GP5   GP6   GP7   GP8   GP4 

And matrix_pins looks like this:

{
    "rows": ["GP0", "GP9", "GP1", "GP2", "GP10", "GP3", "GP11", "GP12", "GP5", "GP29", "GP6"],
    "cols": ["GP28", "GP7", "GP27", "GP8", "GP4", "GP15", "GP14", "GP13"]
}

That's a good looking cat, and the keyboard's nice too!
Great job getting it working with the RP2040 and QMK. I'm still trying to figure them both out.
Cheers
Frank