keychron_qmk_firmware/keyboards/infinity60/keymaps/jpetermans

Backlight for Infinity60

Led Controller Specs

The Infinity60 (revision 1.1a) pcb uses the IS31FL3731C matrix LED driver from ISSI (datasheet). The IS31 has the ability to control two led matrices (A & B), each matrix controlling 9 pins, each pin controlling 8 leds. The Infinity only utilizes matrix A.

Infinity60 LED Map: digits mean "row" and "col", i.e. 45 means pin 4, column 5 in the IS31 datasheet

  11 12 13 14 15 16 17 18 21 22 23 24 25  26 27*
   28 31 32 33 34 35 36 37 38 41 42 43 44 45
   46 47 48 51 52 53 54 55 56 57 58 61    62
   63 64 65 66 67 68 71 72 73 74 75      76 77*
   78  81  82       83         84  85  86  87

*Unused in Alphabet Layout

The IS31 includes 8 led pages (or frames) 0-7 than can be displayed, and each page consists of 144 bytes.

• bytes 0 - 17 - LED control (on/off).
  • 18 bytes which alternate between A and B matrices (A1, B1, A2, B2, ..).
  • Each byte controls the 8 leds on that pin with bits (8 to 1).
• bytes 8 - 35 - Blink control.
  • Same as LED control above, but sets blink on/off.
• bytes 36 - 143 - PWM control.
  • One byte per LED, sets PWM from 0 to 255.
  • Same as above, the register alternates, every 8 bytes (not bits) between the A & B matrices.

Led Controller Code

In the Infinity60 project folder, led_controller.c sets up ability to write led layers at startup or control leds on demand as part of fn_actions. By default led_controller.c assumes page 0 will be used for full on/off. The remaining 7 pages (1-7) are free for preset led maps or single led actions at init or on demand. Communication with the IS31 is primarily done through the led_mailbox using chMBPost described further below under "Sending messages in Keymap.c". This code is based on work matt3o and flabbergast did for tmk firmware on the whitefox.

One function is available to directly set leds without the mailbox:

write_led_page(page#, array of leds by address, # of addresses in array)

This function saves a full page to the controller using a supplied array of led locations such as:

uint8_t led_numpad[16] =  {
  18,21,22,23,
  37,38,41,42,
  55,56,57,58,
  72,73,74,75
}
write_led_page(5, led_numpad, 16);

Remaining led control is done through the led mailbox using these message types:

• SET_FULL_ROW (3 bytes) - message type, 8-bit mask, and row#. Sets all leds on one pin per the bit mask.
• OFF_LED, ON_LED, TOGGLE_LED (3 bytes) - message type, led address, and page#. Off/on/toggle specific led.
• BLINK_OFF_LED, BLINK_ON_LED, BLINK_TOGGLE_LED (3 bytes) - message type, led address, and page#. Set blink Off/on/toggle for specific led.
• TOGGLE_ALL (1 byte) - Turn on/off full backlight.
• TOGGLE_BACKLIGHT (2 bytes) - message type, on/off. Sets backlight completely off, no leds will display.
• DISPLAY_PAGE (2 bytes) - message type, page to display. Switch to specific pre-set page.
• RESET_PAGE (2 bytes) - message type, page to reset. Reset/erase specific page.
• TOGGLE_NUM_LOCK (2 bytes) - message type, on/off (NUM_LOCK_LED_ADDRESS). Toggle numlock on/off. Usually run with the set_leds function to check state of numlock or capslock. If all leds are on (e.i. TOGGLE_ALL) then this sets numlock to blink instead (this is still a little buggy if toggling on/off quickly).
• TOGGLE_CAPS_LOCK (2 bytes) - message type, on/off (CAPS_LOCK_LED_ADDRESS). Same as numlock.
• STEP_BRIGHTNESS (2 bytes) - message type, and step up (1) or step down (0). Increase or decrease led brightness.

Sending messages in Keymap.c

Sending an action to the led mailbox is done using chMBPost:

chMBPost(&led_mailbox, message, timeout);

• &led_mailbox - pointer to led mailbox
• message - up to 4 bytes but most messages use only 2. First byte (LSB) is the message type, the remaining three bytes are the message to process.
• timeout is TIME_IMMEDIATE

An example:

//set the message to be sent. First byte (LSB) is the message type, and second is the led address
msg=(42 << 8) | ON_LED;

//send msg to the led mailbox
chMBPost(&led_mailbox, msg, TIME_IMMEDIATE);

Another:

msg=(46 << 8) | BLINK_TOGGLE_LED;
chMBPost(&led_mailbox, msg, TIME_IMMEDIATE);

Finally, SET_FULL_ROW requires an extra byte with row information in the message so sending this message looks like:

msg=(row<<16) | (led_pin_byte << 8) | SET_FULL_ROW;
chMBPost(&led_mailbox, msg, TIME_IMMEDIATE);