IS31FL3746A Driver

I²C 18x4 LED matrix driver by Lumissil. Supports a maximum of four drivers, each controlling up to 72 single-color LEDs, or 24 RGB LEDs.

IS31FL3746A Datasheet

Usage

The IS31FL3746A driver code is automatically included if you are using the LED Matrix or RGB Matrix feature with the is31fl3746a 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 += is31fl3746a-mono.c # For single-color
SRC += is31fl3746a.c # For RGB
I2C_DRIVER_REQUIRED = yes

Basic Configuration

Add the following to your config.h:

Define	Default	Description
IS31FL3746A_SDB_PIN	Not defined	The GPIO pin connected to the drivers' shutdown pins
IS31FL3746A_I2C_TIMEOUT	100	The I²C timeout in milliseconds
IS31FL3746A_I2C_PERSISTENCE	0	The number of times to retry I²C transmissions
IS31FL3746A_I2C_ADDRESS_1	Not defined	The I²C address of driver 0
IS31FL3746A_I2C_ADDRESS_2	Not defined	The I²C address of driver 1
IS31FL3746A_I2C_ADDRESS_3	Not defined	The I²C address of driver 2
IS31FL3746A_I2C_ADDRESS_4	Not defined	The I²C address of driver 3
IS31FL3746A_CONFIGURATION	0x01	The value of the configuration register
IS31FL3746A_PWM_FREQUENCY	IS31FL3746A_PWM_FREQUENCY_29K_HZ	The PWM frequency of the LEDs
IS31FL3746A_SW_PULLDOWN	IS31FL3746A_PDR_2K_OHM_SW_OFF	The SWx pulldown resistor value
IS31FL3746A_CS_PULLUP	IS31FL3746A_PUR_2K_OHM_CS_OFF	The CSx pullup resistor value
IS31FL3746A_GLOBAL_CURRENT	0xFF	The global current control value

I²C Addressing

The IS31FL3746A has 16 possible 7-bit I²C addresses, depending on how the ADDR1 and ADDR2 pins are connected.

To configure this, set the IS31FL3746A_I2C_ADDRESS_n defines to one of the following in your config.h, where n denotes the driver index:

Define	Value
IS31FL3746A_I2C_ADDRESS_GND_GND	0x60
IS31FL3746A_I2C_ADDRESS_GND_SCL	0x61
IS31FL3746A_I2C_ADDRESS_GND_SDA	0x62
IS31FL3746A_I2C_ADDRESS_GND_VCC	0x63
IS31FL3746A_I2C_ADDRESS_SCL_GND	0x64
IS31FL3746A_I2C_ADDRESS_SCL_SCL	0x65
IS31FL3746A_I2C_ADDRESS_SCL_SDA	0x66
IS31FL3746A_I2C_ADDRESS_SCL_VCC	0x67
IS31FL3746A_I2C_ADDRESS_SDA_GND	0x68
IS31FL3746A_I2C_ADDRESS_SDA_SCL	0x69
IS31FL3746A_I2C_ADDRESS_SDA_SDA	0x6A
IS31FL3746A_I2C_ADDRESS_SDA_VCC	0x6B
IS31FL3746A_I2C_ADDRESS_VCC_GND	0x6C
IS31FL3746A_I2C_ADDRESS_VCC_SCL	0x6D
IS31FL3746A_I2C_ADDRESS_VCC_SDA	0x6E
IS31FL3746A_I2C_ADDRESS_VCC_VCC	0x6F

PWM Frequency

The PWM frequency can be adjusted by adding the following to your config.h:

#define IS31FL3746A_PWM_FREQUENCY IS31FL3746A_PWM_FREQUENCY_29K_HZ

Valid values are:

Define	Frequency
IS31FL3746A_PWM_FREQUENCY_29K_HZ	29 kHz (default)
IS31FL3746A_PWM_FREQUENCY_14K5_HZ	14.5 kHz
IS31FL3746A_PWM_FREQUENCY_7K25_HZ	7.25 kHz
IS31FL3746A_PWM_FREQUENCY_3K63_HZ	3.63 kHz
IS31FL3746A_PWM_FREQUENCY_1K81_HZ	1.81 kHz
IS31FL3746A_PWM_FREQUENCY_906_HZ	906 Hz
IS31FL3746A_PWM_FREQUENCY_453_HZ	453 Hz

De-Ghosting

These settings control the pulldown and pullup resistor values on the SWy and CSx pins respectively, for the purposes of eliminating ghosting. Refer to the datasheet (p. 23) for more information on how and why this occurs.

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

#define IS31FL3746A_SW_PULLDOWN IS31FL3746A_PDR_2K_OHM_SW_OFF
#define IS31FL3746A_CS_PULLUP IS31FL3746A_PUR_2K_OHM_CS_OFF

Valid values for IS31FL3746A_SW_PULLDOWN are:

Define	Resistance
IS31FL3746A_PDR_0_OHM	None
IS31FL3746A_PDR_0K5_OHM_SW_OFF	0.5 kΩ in SWx off time
IS31FL3746A_PDR_1K_OHM_SW_OFF	1 kΩ in SWx off time
IS31FL3746A_PDR_2K_OHM_SW_OFF	2 kΩ in SWx off time (default)
IS31FL3746A_PDR_1K_OHM	1 kΩ
IS31FL3746A_PDR_2K_OHM	2 kΩ
IS31FL3746A_PDR_4K_OHM	4 kΩ
IS31FL3746A_PDR_8K_OHM	8 kΩ

Valid values for IS31FL3746A_CS_PULLUP are:

Define	Resistance
IS31FL3746A_PUR_0_OHM	None (default)
IS31FL3746A_PUR_0K5_OHM_CS_OFF	0.5 kΩ in CSy off time
IS31FL3746A_PUR_1K_OHM_CS_OFF	1 kΩ in CSy off time
IS31FL3746A_PUR_2K_OHM_CS_OFF	2 kΩ in CSy off time (default)
IS31FL3746A_PUR_1K_OHM	1 kΩ
IS31FL3746A_PUR_2K_OHM	2 kΩ
IS31FL3746A_PUR_4K_OHM	4 kΩ
IS31FL3746A_PUR_8K_OHM	8 kΩ

Global Current Control

This setting controls the current sunk by the CSy 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 IS31FL3746A_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 is31fl3746a_led_t PROGMEM g_is31fl3746a_leds[IS31FL3746A_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 is31fl3746a_led_t PROGMEM g_is31fl3746a_leds[IS31FL3746A_LED_COUNT] = {
/* Driver
 *   |  V */
    {0, SW1_CS1},
    // etc...
};

These values correspond to the register indices as shown in the datasheet on page 13, figure 8.

API

struct is31fl3746a_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 is31fl3746a_init(uint8_t index)

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

Arguments

• uint8_t index
  The driver index.
• uint8_t sync
  Sync configuration of the LED driver.

---

void is31fl3746a_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 is31fl3746a_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 is31fl3746a_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 is31fl3746a_update_pwm_buffers() after you are finished.

Arguments

• int index
  The LED index (ie. the index into the g_is31fl3746a_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 is31fl3746a_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 is31fl3746a_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 is31fl3746a_update_pwm_buffers() after you are finished.

Arguments

• int index
  The LED index (ie. the index into the g_is31fl3746a_leds array).
• uint8_t value
  The brightness value to set.

---

void is31fl3746a_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 is31fl3746a_set_scaling_register(uint8_t index, uint8_t red, uint8_t green, uint8_t blue)

Configure the scaling registers for a single LED (RGB driver only). This function does not immediately update the LEDs; call is31fl3746a_update_scaling_registers() after you are finished.

Arguments

• uint8_t index
  The LED index (ie. the index into the g_is31fl3746a_leds array).
• uint8_t red
  The scaling value for the red channel.
• uint8_t green
  The scaling value for the green channel.
• uint8_t blue
  The scaling value for the blue channel.

---

void is31fl3746a_set_scaling_register(uint8_t index, uint8_t value)

Configure the scaling register for a single LED (single-color driver only). This function does not immediately update the LEDs; call is31fl3746a_update_scaling_registers() after you are finished.

Arguments

• uint8_t index
  The LED index (ie. the index into the g_is31fl3746a_leds array).
• uint8_t value
  The scaling value for the LED.

---

void is31fl3746a_update_pwm_buffers(uint8_t index)

Flush the PWM values to the LED driver.

Arguments

• uint8_t index
  The driver index.

---

void is31fl3746a_update_scaling_registers(uint8_t index)

Flush the scaling register values to the LED driver.

Arguments

• uint8_t index
  The driver index.