RIALTO SBC/Interfaces and Connectors/Led and buttons
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Contents
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.
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/pca955xsyfs interface - the KEY buttons can be detected via
/dev/input/event1input devices- KEY0 is mapped to
KEY_F1 - KEY1 is mapped to
KEY_F2 - the mapping can be easily modified in the device tree file
- KEY0 is mapped to
