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qmk-firmware/docs/drivers/is31fl3741.md

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IS31FL3741 Driver

I²C 39x9 LED matrix driver by Lumissil. Supports a maximum of four drivers, each controlling up to 351 single-color LEDs, or 117 RGB LEDs.

IS31FL3741A Datasheet

Usage

The IS31FL3741 driver code is automatically included if you are using the LED Matrix or RGB Matrix feature with the is31fl3741 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 += is31fl3741-mono.c # For single-color
SRC += is31fl3741.c # For RGB
I2C_DRIVER_REQUIRED = yes

Basic Configuration

Add the following to your config.h:

Define Default Description
IS31FL3741_SDB_PIN Not defined The GPIO pin connected to the drivers' shutdown pins
IS31FL3741_I2C_TIMEOUT 100 The I²C timeout in milliseconds
IS31FL3741_I2C_PERSISTENCE 0 The number of times to retry I²C transmissions
IS31FL3741_I2C_ADDRESS_1 Not defined The I²C address of driver 0
IS31FL3741_I2C_ADDRESS_2 Not defined The I²C address of driver 1
IS31FL3741_I2C_ADDRESS_3 Not defined The I²C address of driver 2
IS31FL3741_I2C_ADDRESS_4 Not defined The I²C address of driver 3
IS31FL3741_CONFIGURATION 1 The value of the configuration register
IS31FL3741_PWM_FREQUENCY IS31FL3741_PWM_FREQUENCY_29K_HZ The PWM frequency of the LEDs (IS31FL3741A only)
IS31FL3741_SW_PULLUP IS31FL3741_PUR_32K_OHM The SWx pullup resistor value
IS31FL3741_CS_PULLDOWN IS31FL3741_PDR_32K_OHM The CSx pulldown resistor value
IS31FL3741_GLOBAL_CURRENT 0xFF The global current control value

I²C Addressing

The IS31FL3741 has four possible 7-bit I²C addresses, depending on how the ADDR pin is connected.

To configure this, set the IS31FL3741_I2C_ADDRESS_n defines to one of the following in your config.h, where n denotes the driver index:

Define Value
IS31FL3741_I2C_ADDRESS_GND 0x30
IS31FL3741_I2C_ADDRESS_SCL 0x31
IS31FL3741_I2C_ADDRESS_SDA 0x32
IS31FL3741_I2C_ADDRESS_VCC 0x33

PWM Frequency

The PWM frequency can be adjusted (for IS31FL3741A only) by adding the following to your config.h:

#define IS31FL3741_PWM_FREQUENCY IS31FL3741_PWM_FREQUENCY_29K_HZ

Valid values are:

Define Frequency
IS31FL3741_PWM_FREQUENCY_29K_HZ 29 kHz (default)
IS31FL3741_PWM_FREQUENCY_3K6_HZ 3.6 kHz
IS31FL3741_PWM_FREQUENCY_1K8_HZ 1.8 kHz
IS31FL3741_PWM_FREQUENCY_900_HZ 900 Hz

De-Ghosting

These settings control the pullup and pulldown resistor values on the CSx and SWy pins respectively, for the purposes of eliminating ghosting. Refer to the datasheet (p. 18) for more information on how and why this occurs.

To adjust the resistor values, add the following to your config.h:

#define IS31FL3741_SW_PULLUP IS31FL3741_PUR_32K_OHM
#define IS31FL3741_CS_PULLDOWN IS31FL3741_PDR_32K_OHM

Valid values for IS31FL3741_SW_PULLUP are:

Define Resistance
IS31FL3741_PUR_0_OHM None
IS31FL3741_PUR_0K5_OHM 0.5 kΩ
IS31FL3741_PUR_1K_OHM 1 kΩ
IS31FL3741_PUR_2K_OHM 2 kΩ
IS31FL3741_PUR_4K_OHM 4 kΩ
IS31FL3741_PUR_8K_OHM 8 kΩ
IS31FL3741_PUR_16K_OHM 16 kΩ
IS31FL3741_PUR_32K_OHM 32 kΩ (default)

Valid values for IS31FL3741_CS_PULLDOWN are:

Define Resistance
IS31FL3741_PDR_0_OHM None
IS31FL3741_PDR_0K5_OHM 0.5 kΩ
IS31FL3741_PDR_1K_OHM 1 kΩ
IS31FL3741_PDR_2K_OHM 2 kΩ
IS31FL3741_PDR_4K_OHM 4 kΩ
IS31FL3741_PDR_8K_OHM 8 kΩ
IS31FL3741_PDR_16K_OHM 16 kΩ
IS31FL3741_PDR_32K_OHM 32 kΩ (default)

Global Current Control

This setting controls the current sunk by the CSx pins, from 0 to 255. By default, the value is the maximum (255), but if you need to lower it, add the following to your config.h:

#define IS31FL3741_GLOBAL_CURRENT 0xFF

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 is31fl3741_led_t PROGMEM g_is31fl3741_leds[IS31FL3741_LED_COUNT] = {
/* Driver
 *   |  R         G         B */
    {0, SW1_CS1,  SW1_CS2,  SW1_CS3},
    // etc...
};

In this example, the red, green and blue channels for the first LED index on driver 0 all have their anodes connected to the SW1 pin, and their cathodes on the CS1, CS2 and CS3 pins respectively.

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

const is31fl3741_led_t PROGMEM g_is31fl3741_leds[IS31FL3741_LED_COUNT] = {
/* Driver
 *   |  V */
    {0, SW1_CS1},
    // etc...
};

These values correspond to the register indices as shown in the datasheet on page 12, figure 8.

API

struct is31fl3741_led_t

Contains the PWM register addresses for a single RGB LED.

Members

  • uint32_t driver
    The driver index of the LED, from 0 to 3.
  • uint32_t r
    The output PWM register address for the LED's red channel (RGB driver only).
  • uint32_t g
    The output PWM register address for the LED's green channel (RGB driver only).
  • uint32_t b
    The output PWM register address for the LED's blue channel (RGB driver only).
  • uint32_t v
    The output PWM register address for the LED (single-color driver only).

void is31fl3741_init(uint8_t index)

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

Arguments

  • uint8_t index
    The driver index.

void is31fl3741_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 is31fl3741_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 is31fl3741_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 is31fl3741_update_pwm_buffers() after you are finished.

Arguments

  • int index
    The LED index (ie. the index into the g_is31fl3741_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 is31fl3741_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 is31fl3741_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 is31fl3741_update_pwm_buffers() after you are finished.

Arguments

  • int index
    The LED index (ie. the index into the g_is31fl3741_leds array).
  • uint8_t value
    The brightness value to set.

void is31fl3741_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 is31fl3741_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 is31fl3741_update_led_control_registers() after you are finished.

Arguments

  • uint8_t index
    The LED index (ie. the index into the g_is31fl3741_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 is31fl3741_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 is31fl3741_update_led_control_registers() after you are finished.

Arguments

  • uint8_t index
    The LED index (ie. the index into the g_is31fl3741_leds array).
  • bool value
    Enable or disable the LED.

void is31fl3741_update_pwm_buffers(uint8_t index)

Flush the PWM values to the LED driver.

Arguments

  • uint8_t index
    The driver index.

void is31fl3741_update_led_control_registers(uint8_t index)

Flush the LED control register values to the LED driver.

Arguments

  • uint8_t index
    The driver index.