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How to use the SPI ports
This article illustrates how to use the SPI ports on Acme Systems Road Runner SOM based on Microchip
SAMA5D27 MPU
Pinout of SPI ports
The SPI bus lines are located on the following pins:
| Signal | Per A | Per B | Per C | Per D | Per E | Per F
|------------|-------|-------|-------|-------|-------|-------
| SPI0 MOSI | PA15 | | PB0 | | |
| SPI0 MISO | PA16 | | PA31 | | |
| SPI0 SCLK | PA14 | | PB1 | | |
| SPI0 CS0 | PA17 | | PA30 | | |
| SPI0 CS1 | PA18 | | PA29 | | |
| SPI0 CS2 | PA19 | | PA27 | | |
| SPI0 CS3 | PA20 | | PA28 | | |
!------------|-------|-------|-------|-------|-------|-------
| SPI1 MOSI | PD26 | | | PC2 | PA23 |
| SPI1 MISO | PD27 | | | PC3 | PA24 |
| SPI1 SCLK | PD25 | | | PC1 | PA25 |
| SPI1 CS0 | PD28 | | | PC4 | PA22 |
| SPI1 CS1 | PD29 | | | PC5 | PA26 |
| SPI1 CS2 | PD30 | | | PC6 | PA27 |
| SPI1 CS3 | | | | PC7 | PA28 |
|------------|-------|-------|-------|-------|-------|-------
Kernel configuration
Device Drivers --->
[*] SPI support --->
<*> Atmel SPI Controller
<*> User mode SPI device driver support
Device tree
/****************/
/* Enable SPI 0 */
/****************/
spi0: spi@f8000000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_spi0_default>;
status = "okay";
spidev@0 {
compatible = "linux,spidev";
spi-max-frequency = <10000000>;
reg = <0>;
};
};
/* Pin definition Peripheral A */
pinctrl_spi0_default: spi0_default {
pinmux = <PIN_PA14__SPI0_SPCK>,
<PIN_PA15__SPI0_MOSI>,
<PIN_PA16__SPI0_MISO>,
<PIN_PA17__SPI0_NPCS0>,
<PIN_PA18__SPI0_NPCS1>,
<PIN_PA19__SPI0_NPCS2>,
<PIN_PA20__SPI0_NPCS3>;
bias-disable;
};
/****************/
/* Enable SPI 1 */
/****************/
spi1: spi@fc000000 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_spi1_default>;
status = "okay";
spidev@0 {
compatible = "linux,spidev";
spi-max-frequency = <10000000>;
reg = <0>;
};
};
/* Pin definition Peripheral D */
pinctrl_spi1_default: spi1_default {
pinmux = <PIN_PC1__SPI1_SPCK>,
<PIN_PC2__SPI1_MOSI>,
<PIN_PC3__SPI1_MISO>,
<PIN_PC4__SPI1_NPCS0>;
bias-disable;
};
Links
- Microchip SAMA5D2 Series datasheet
- Use 2.8 inch TFT displays on SPI ports
- Overview of Linux kernel SPI support
- Intro to the userspace API for spi devices
- Example of Device Tree
Related products
- CPU Microchip SAMA5D27
- Cortex A5 @ 500 MHz
- Very low power consumption:
396mW in full speed mode
198mW at Linux prompt
17mW in standby mode
10mW in suspend to RAM mode - Armhf architecture
- DDR3L RAM 256 MB
- QuadSPI 0/16/64/128MB
- Size: 40x30 mm
- Plug-in module
- 200 pins 0.4 mm pitch
- TFT parallel interface
- Boot from internal Quad SPI or external uSD/eMMC
- Linux Kernel 5.15 LTS
- Debian, Buildroot and Yocto
- Open source drivers
- Single Board Computer based on RoadRunner Linux SOM (Included)
- Classic "Credit Card" form factor
- Two USB Host 2.0 ports (one configurable as USB client on the USB-C connector)
- One 10/100 Mbit/s Lan port
- Two AcmeSensor ports
- Double placements for 2.54mm pitch 20x2 pinstrips (not soldered) for GPIOS, SPI, I2C, Serial etc ports
- Credit Card footprint
