RIALTO SBC/Interfaces and Connectors/Led and buttons

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History
Issue Date Notes
2024/01/13 First documentation release



Led and buttons connector[edit | edit source]

Description[edit | edit source]

RIALTO SBC can drive up to six leds and detect two key buttons at the expansion connector J70.

J70 is a 10x1x2.54mm pin strip header connector.


Led and buttons connector (J70)

Signals[edit | edit source]

The six LED output are driven by a PCA9551PW integrated circuit. In the following table describes the IC output pins to the connector J70:

Pin# Pin name PCA9551 output PCA9551 pin
1 3V3_IO
2 AUX_LED0 LED7 12
3 AUX_LED1 LED6 11
4 AUX_LED2 LED5 10
5 AUX_LED3 LED4 9
6 AUX_LED4 LED0 4
7 AUX_LED5 LED1 5
10 DGND

The two KEY input are connected to the i.MX6UL SoC or (optionally) to the PCA9551PW IC. The following table describes the interface signals:

Pin# Pin name PCA9551 input PCA9551 pin GPIO
8 LCD_RESET LED2 6 GPIO3_IO04
9 LCD_ENABLE LED3 7 GPIO3_IO01

All the GPIO signals are 0-3.3V level.

Device mapping[edit | edit source]

The led are mapped to a sysfs led class interface. The button are mapped to the input event device handler.

Device usage[edit | edit source]

Under Linux:

  • the LEDs can be manipulated via /sys/class/leds/pca955x syfs interface
  • the KEY buttons can be detected via /dev/input/event1 input devices
    • KEY0 is mapped to KEY_F1
    • KEY1 is mapped to KEY_F2
    • the mapping can be easily modified in the device tree file