IS31FL3745 Driver

I²C 18x8 LED matrix driver by Lumissil. Supports a maximum of four drivers, each controlling up to 144 single-color LEDs, or 48 RGB LEDs.

IS31FL3745 Datasheet

Usage

The IS31FL3745 driver code is automatically included if you are using the LED Matrix or RGB Matrix feature with the is31fl3745 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 += is31fl3745-mono.c # For single-color
SRC += is31fl3745.c # For RGB
I2C_DRIVER_REQUIRED = yes

Basic Configuration

Add the following to your config.h:

Define	Default	Description
IS31FL3745_SDB_PIN	Not defined	The GPIO pin connected to the drivers' shutdown pins
IS31FL3745_I2C_TIMEOUT	100	The I²C timeout in milliseconds
IS31FL3745_I2C_PERSISTENCE	0	The number of times to retry I²C transmissions
IS31FL3745_I2C_ADDRESS_1	Not defined	The I²C address of driver 0
IS31FL3745_I2C_ADDRESS_2	Not defined	The I²C address of driver 1
IS31FL3745_I2C_ADDRESS_3	Not defined	The I²C address of driver 2
IS31FL3745_I2C_ADDRESS_4	Not defined	The I²C address of driver 3
IS31FL3745_SYNC_1	IS31FL3745_SYNC_NONE	The sync configuration for driver 0
IS31FL3745_SYNC_2	IS31FL3745_SYNC_NONE	The sync configuration for driver 1
IS31FL3745_SYNC_3	IS31FL3745_SYNC_NONE	The sync configuration for driver 2
IS31FL3745_SYNC_4	IS31FL3745_SYNC_NONE	The sync configuration for driver 3
IS31FL3745_CONFIGURATION	0x31	The value of the configuration register
IS31FL3745_SW_PULLDOWN	IS31FL3745_PDR_2K_OHM_SW_OFF	The SWx pulldown resistor value
IS31FL3745_CS_PULLUP	IS31FL3745_PUR_2K_OHM_CS_OFF	The CSx pullup resistor value
IS31FL3745_GLOBAL_CURRENT	0xFF	The global current control value

I²C Addressing

The IS31FL3745 has 16 possible 7-bit I²C addresses, depending on how the ADDR1 and ADDR2 pins are connected.

To configure this, set the IS31FL3745_I2C_ADDRESS_n defines to one of the following in your config.h, where n denotes the driver index:

Define	Value
IS31FL3745_I2C_ADDRESS_GND_GND	0x20
IS31FL3745_I2C_ADDRESS_GND_SCL	0x21
IS31FL3745_I2C_ADDRESS_GND_SDA	0x22
IS31FL3745_I2C_ADDRESS_GND_VCC	0x23
IS31FL3745_I2C_ADDRESS_SCL_GND	0x24
IS31FL3745_I2C_ADDRESS_SCL_SCL	0x25
IS31FL3745_I2C_ADDRESS_SCL_SDA	0x26
IS31FL3745_I2C_ADDRESS_SCL_VCC	0x27
IS31FL3745_I2C_ADDRESS_SDA_GND	0x28
IS31FL3745_I2C_ADDRESS_SDA_SCL	0x29
IS31FL3745_I2C_ADDRESS_SDA_SDA	0x2A
IS31FL3745_I2C_ADDRESS_SDA_VCC	0x2B
IS31FL3745_I2C_ADDRESS_VCC_GND	0x2C
IS31FL3745_I2C_ADDRESS_VCC_SCL	0x2D
IS31FL3745_I2C_ADDRESS_VCC_SDA	0x2E
IS31FL3745_I2C_ADDRESS_VCC_VCC	0x2F

Multi-Driver Synchronization

Multiple IS31FL3745 drivers can be synchronized by connecting the SYNC pins together. One driver must be designated as the "master", and the others configured as "slave".

To do this, set the IS31FL3745_SYNC_n defines accordingly in your config.h, where n denotes the driver index:

Define	Value
IS31FL3745_SYNC_NONE	No synchronization
IS31FL3745_SYNC_MASTER	Driver configured as master
IS31FL3745_SYNC_SLAVE	Driver configured as slave

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 IS31FL3745_SW_PULLDOWN IS31FL3745_PDR_2K_OHM_SW_OFF
#define IS31FL3745_CS_PULLUP IS31FL3745_PUR_2K_OHM_CS_OFF

Valid values for IS31FL3745_SW_PULLDOWN are:

Define	Resistance
IS31FL3745_PDR_0_OHM	None (default)
IS31FL3745_PDR_0K5_OHM_SW_OFF	0.5 kΩ in SWx off time
IS31FL3745_PDR_1K_OHM_SW_OFF	1 kΩ in SWx off time
IS31FL3745_PDR_2K_OHM_SW_OFF	2 kΩ in SWx off time (default)
IS31FL3745_PDR_1K_OHM	1 kΩ
IS31FL3745_PDR_2K_OHM	2 kΩ
IS31FL3745_PDR_4K_OHM	4 kΩ
IS31FL3745_PDR_8K_OHM	8 kΩ

Valid values for IS31FL3745_CS_PULLUP are:

Define	Resistance
IS31FL3745_PUR_0_OHM	None (default)
IS31FL3745_PUR_0K5_OHM_CS_OFF	0.5 kΩ in CSy off time
IS31FL3745_PUR_1K_OHM_CS_OFF	1 kΩ in CSy off time
IS31FL3745_PUR_2K_OHM_CS_OFF	2 kΩ in CSy off time (default)
IS31FL3745_PUR_1K_OHM	1 kΩ
IS31FL3745_PUR_2K_OHM	2 kΩ
IS31FL3745_PUR_4K_OHM	4 kΩ
IS31FL3745_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 IS31FL3745_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 is31fl3745_led_t PROGMEM g_is31fl3745_leds[IS31FL3745_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 is31fl3745_led_t PROGMEM g_is31fl3745_leds[IS31FL3745_LED_COUNT] = {
/* Driver
 *   |  V */
    {0, SW1_CS1},
    // etc...
};

These values correspond to the register indices as shown in the datasheet on page 12, figure 9.

API

struct is31fl3745_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 is31fl3745_init(uint8_t index)

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

Arguments

• uint8_t index
  The driver index.

---

void is31fl3745_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 is31fl3745_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 is31fl3745_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 is31fl3745_update_pwm_buffers() after you are finished.

Arguments

• int index
  The LED index (ie. the index into the g_is31fl3745_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 is31fl3745_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 is31fl3745_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 is31fl3745_update_pwm_buffers() after you are finished.

Arguments

• int index
  The LED index (ie. the index into the g_is31fl3745_leds array).
• uint8_t value
  The brightness value to set.

---

void is31fl3745_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 is31fl3745_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 is31fl3745_update_scaling_registers() after you are finished.

Arguments

• uint8_t index
  The LED index (ie. the index into the g_is31fl3745_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 is31fl3745_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 is31fl3745_update_scaling_registers() after you are finished.

Arguments

• uint8_t index
  The LED index (ie. the index into the g_is31fl3745_leds array).
• uint8_t value
  The scaling value for the LED.

---

void is31fl3745_update_pwm_buffers(uint8_t index)

Flush the PWM values to the LED driver.

Arguments

• uint8_t index
  The driver index.

---

void is31fl3745_update_scaling_registers(uint8_t index)

Flush the scaling register values to the LED driver.

Arguments

• uint8_t index
  The driver index.