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Manage the special GPIO lines
This article explais how to use as normal IO lines some special GPIOs
PD14...PD18
This pins are defined by default as JTAG pins. To use them as normal GPIO it is possible to change the fuse configuration using SAM-BA or force the SAMA5D27 CPU to set them as normal GPIO.
In this last case use the Dougg Gilbert GPIO utilities and add these line at Linux startup:
# mem2io -w -i fc0380c0,7c000
# mem2io -w -i fc0380c4,200
PA30
PA30 has by default an internal pull down resistor and is used as SDMMC1_CD signal.
To use it as normal GPIO use this command (Dougg Gilbert GPIO utilities):
mem2io -w -i fc038000,40000000 e mem2io -w -i fc038004,200
How to set pins as GPIO using the device tree
To set as normal GPIO some pins inside the device tree use a section like this adding the pins you need:
pinctrl_gpio: gpio_default {
pinmux = <PIN_PA12__GPIO>,
<PIN_PD31__GPIO>,
<PIN_PB22__GPIO>,
<PIN_PC9__GPIO>,
<PIN_PB17__GPIO>,
<PIN_PB16__GPIO>,
<PIN_PD13__GPIO>,
<PIN_PD16__GPIO>,
<PIN_PD18__GPIO>;
bias-pull-down;
};
To compile the device tree follow this article:
Related products
Low-power Linux System On Module
- CPU Microchip SAMA5D27
- Cortex A5 @ 500 MHz
- Low power consumption:
Suspend to RAM mode 10mW
Full speed: 396mW - Debian, Buildroot and Yocto Linux
- Fully open source drivers
Single Board Computer based on RoadRunner Linux SOM (Included)
- Low power consumption
- Two USB Host 2.0 ports (one configurable as USB client on the USB-C connector)
- One 10/100 Mbit/s Lan port
- 2 Acme Sensor ports
- Huge set of GPIOS, SPI, I2C and serial lines
Evaluation board for RoadRunner SOM
- All the circuitries you need to test the RoadRunner SOM
- USB host, USB device, Ethernet port, MicroSD socket
- Test points for power consumption measurements
- All the Roadrunner signals exposed on 2.54mm pitch pins
- On-board supercap for RTC and backup memory circuit
