keychron_qmk_firmware/docs/drivers/is31fl3731.md

IS31FL3731 Driver

I²C Charlieplexed 16x9 LED matrix driver by Lumissil. Supports a maximum of four drivers, each controlling up to 144 single-color LEDs, or 48 RGB LEDs.

IS31FL3731 Datasheet

Usage

The IS31FL3731 driver code is automatically included if you are using the LED Matrix or RGB Matrix feature with the is31fl3731 driver set, and you would use those APIs instead.

However, if you need to use the driver standalone, add this to your rules.mk:

COMMON_VPATH += $(DRIVER_PATH)/led/issi
SRC += is31fl3731-mono.c # For single-color
SRC += is31fl3731.c # For RGB
I2C_DRIVER_REQUIRED = yes

Basic Configuration

Add the following to your config.h:

Define	Default	Description
IS31FL3731_SDB_PIN	Not defined	The GPIO pin connected to the drivers' shutdown pins
IS31FL3731_I2C_TIMEOUT	100	The I²C timeout in milliseconds
IS31FL3731_I2C_PERSISTENCE	0	The number of times to retry I²C transmissions
IS31FL3731_I2C_ADDRESS_1	Not defined	The I²C address of driver 0
IS31FL3731_I2C_ADDRESS_2	Not defined	The I²C address of driver 1
IS31FL3731_I2C_ADDRESS_3	Not defined	The I²C address of driver 2
IS31FL3731_I2C_ADDRESS_4	Not defined	The I²C address of driver 3
IS31FL3731_DEGHOST	Not defined	Enable ghost image prevention

I²C Addressing

The IS31FL3731 has four possible 7-bit I²C addresses, depending on how the AD pin is connected.

To configure this, set the IS31FL3731_I2C_ADDRESS_n defines to one of the following in your config.h, where n denotes the driver index:

Define	Value
IS31FL3731_I2C_ADDRESS_GND	0x74
IS31FL3731_I2C_ADDRESS_SCL	0x75
IS31FL3731_I2C_ADDRESS_SDA	0x76
IS31FL3731_I2C_ADDRESS_VCC	0x77

De-Ghosting

This setting enables the de-ghosting feature on the IS31FL3731. See this Application Note (p. 15) for more information.

To enable, add the following to your config.h:

#define IS31FL3731_DEGHOST

ARM/ChibiOS Configuration

Depending on the ChibiOS board configuration, you may need to enable and configure I²C at the keyboard level.

LED Mapping

In order to use this driver, each output must be mapped to an LED index, by adding the following to your <keyboardname>.c:

const is31fl3731_led_t PROGMEM g_is31fl3731_leds[IS31FL3731_LED_COUNT] = {
/* Driver
 *   |  R     G     B */
    {0, C1_1, C1_2, C1_3},
    // etc...
};

In this example, the red, green and blue channels for the first LED index on driver 0 all have their cathodes connected to the CA1 pin, and their anodes on the CA2, CA3 and CA4 pins respectively.

For the single-color driver, the principle is the same, but there is only one channel:

const is31fl3731_led_t PROGMEM g_is31fl3731_leds[IS31FL3731_LED_COUNT] = {
/* Driver
 *   |  V */
    {0, C1_1},
    // etc...
};

These values correspond to the register indices as shown in the datasheet on page 11, figure 8.

API

struct is31fl3731_led_t

Contains the PWM register addresses for a single RGB LED.

Members

• uint8_t driver
  The driver index of the LED, from 0 to 3.
• uint8_t r
  The output PWM register address for the LED's red channel (RGB driver only).
• uint8_t g
  The output PWM register address for the LED's green channel (RGB driver only).
• uint8_t b
  The output PWM register address for the LED's blue channel (RGB driver only).
• uint8_t v
  The output PWM register address for the LED (single-color driver only).

---

void is31fl3731_init(uint8_t index)

Initialize the LED driver. This function should be called first.

Arguments

• uint8_t index
  The driver index.

---

void is31fl3731_write_register(uint8_t index, uint8_t reg, uint8_t data)

Set the value of the given register.

Arguments

• uint8_t index
  The driver index.
• uint8_t reg
  The register address.
• uint8_t data
  The value to set.

---

void is31fl3731_select_page(uint8_t index, uint8_t page)

Change the current page for configuring the LED driver.

Arguments

• uint8_t index
  The driver index.
• uint8_t page
  The page number to select.

---

void is31fl3731_set_color(int index, uint8_t red, uint8_t green, uint8_t blue)

Set the color of a single LED (RGB driver only). This function does not immediately update the LEDs; call is31fl3731_update_pwm_buffers() after you are finished.

Arguments

• int index
  The LED index (ie. the index into the g_is31fl3731_leds array).
• uint8_t red
  The red value to set.
• uint8_t green
  The green value to set.
• uint8_t blue
  The blue value to set.

---

void is31fl3731_set_color_all(uint8_t red, uint8_t green, uint8_t blue)

Set the color of all LEDs (RGB driver only).

Arguments

• uint8_t red
  The red value to set.
• uint8_t green
  The green value to set.
• uint8_t blue
  The blue value to set.

---

void is31fl3731_set_value(int index, uint8_t value)

Set the brightness of a single LED (single-color driver only). This function does not immediately update the LEDs; call is31fl3731_update_pwm_buffers() after you are finished.

Arguments

• int index
  The LED index (ie. the index into the g_is31fl3731_leds array).
• uint8_t value
  The brightness value to set.

---

void is31fl3731_set_value_all(uint8_t value)

Set the brightness of all LEDs (single-color driver only).

Arguments

• uint8_t value
  The brightness value to set.

---

void is31fl3731_set_led_control_register(uint8_t index, bool red, bool green, bool blue)

Configure the LED control registers for a single LED (RGB driver only). This function does not immediately update the LEDs; call is31fl3731_update_led_control_registers() after you are finished.

Arguments

• uint8_t index
  The LED index (ie. the index into the g_is31fl3731_leds array).
• bool red
  Enable or disable the red channel.
• bool green
  Enable or disable the green channel.
• bool blue
  Enable or disable the blue channel.

---

void is31fl3731_set_led_control_register(uint8_t index, bool value)

Configure the LED control registers for a single LED (single-color driver only). This function does not immediately update the LEDs; call is31fl3731_update_led_control_registers() after you are finished.

Arguments

• uint8_t index
  The LED index (ie. the index into the g_is31fl3731_leds array).
• bool value
  Enable or disable the LED.

---

void is31fl3731_update_pwm_buffers(uint8_t index)

Flush the PWM values to the LED driver.

Arguments

• uint8_t index
  The driver index.

---

void is31fl3731_update_led_control_registers(uint8_t index)

Flush the LED control register values to the LED driver.

Arguments

• uint8_t index
  The driver index.