Zero/dev/libmraa
Radxa Zero > Development Guide > Install Libmraa
Contents
Libmraa on Radxa Zero
This guide describes how to use libmraa on Radxa Zero to access GPIO, SPI, and other peripherals.
Requirement
- Radxa Zero
- You need our latest official image
Install essential packages
Prebuilt libmraa is located in our Radxa APT Focal and Buster repositories.
Update your /etc/apt/sources.list.d/apt-radxa-com.list accordingly to enable Radxa APT repository.
For Ubuntu Focal:
root@zero:~# cat /etc/apt/sources.list.d/apt-radxa-com.list deb http://apt.radxa.com/focal-stable/ focal main deb http://apt.radxa.com/focal-testing/ focal main
For Debian Buster:
root@zero:~# cat /etc/apt/sources.list.d/apt-radxa-com.list deb http://apt.radxa.com/buster-stable/ buster main deb http://apt.radxa.com/buster-testing/ buster main
Install libmraa:
rock@zero:~$ sudo apt update rock@zero:~$ sudo apt install libmraa
Optionally, install compiler if you want to run some tests:
rock@zero:~$ sudo apt install build-essential
Enable interface
Radxa Zero has a 40-pin color coded expansion header. See Radxa Zero GPIO pintout for more detail on pin definition.
mraa pin definition is configured as follow:
23 GPIO:
PIN03 GPIOA_14 PIN05 GPIOA_15 PIN07 GPIOAO_3 PIN08 GPIOAO_0 PIN10 GPIOAO_1 PIN11 GPIOAO_2 PIN12 GPIOX_9 PIN13 GPIOX_11 PIN16 GPIOX_10 PIN18 GPIOX_8 PIN19 GPIOH_4 PIN21 GPIOH_5 PIN22 GPIOC_7 //Not supported gpio funtion now PIN23 GPIOH_7 PIN24 GPIOH_6 PIN27 GPIOAO_3 PIN28 GPIOAO_2 PIN32 GPIOAO_4 PIN35 GPIOAO_8 PIN36 GPIOH_8 PIN37 GPIOAO_9 PIN38 GPIOAO_10 PIN40 GPIOAO_11
3 I2C:
PIN23 I2C1_SCL PIN24 I2C1_SDA PIN13 I2C1_SCL PIN16 I2C1_SDA //these are two i2c-1, only one can be opened when using PIN3 I2C3_SDA PIN5 I2C3_SCL PIN7 I2C4_SDA PIN11 I2C4_SCL PIN27 I2C4_SDA PIN28 I2C4_SCL ///these are two i2c-4, only one can be opened when using
2 SPI: pwm_c
PIN12 SPI0RX //must disable i2c1 uart1 pwm_c PIN13 SPI0CLK PIN16 SPI0CSN PIN18 SPI0TX PIN19 SPI1TX //must disable i2c1 uart4 PIN21 SPI1RX PIN23 SPI1CLK PIN24 SPI1CSN
3 UART:
PIN8 UART0_TX PIN10 UART0_RX PIN7 UART1_RX //must disable i2c4 PIN11 UART1_TX PIN27 UART1_RX PIN28 UART1_TX PIN23 UART4_TX //must disable i2c1 spi1 PIN24 UART4_RX
2 PWM:
PIN18 PWM18 PIN40 PWM40
Since many peripherals are reusing the same physical pin, all but one has to be disabled to allow proper functionality. While in a normal PC user can easily disable or enable peripherals in their UEFI firmware, currently there is no such universal equivalent in ARM world. Instead, Device tree blobs (dtb) and Device tree overlays (dtbo) are used to inform Linux kernel the existence of external devices. Please refer to this guide on available dtbo for Radxa Zero and here on how to specify the correct dtbo. Please read those carefully or you may get an unbootable system.
Run libmraa tests
After set correct dtbo to use, reboot Radxa Zero for change to take effect. You can now try some examples supplied by libmraa. They can be used to test SPI, UART, I2C, GPIO, and so on.
In this example, we will use the sample files located under /usr/local/share/mraa/examples/c.
Let's first copy them to your home directory so we can modify them later:
rock@zero:~$ cp -av /usr/local/share/mraa/examples/c /home/rock/mraa-examples
GPIO test
Use mraa-gpio tool to test GPIO:
root@rockpis:~# mraa-gpio list 01 3V3: 02 5V: 03 I2C_EE_M3_S: GPIO I2C 04 5V: 05 I2C_EE_M3_S: GPIO I2C 06 GND: 07 I2C_AO_M0_S: GPIO I2C UART 08 UART_AO_A_T: GPIO UART 09 GND: 10 UART_AO_A_R: GPIO UART 11 I2C_AO_M0_S: GPIO I2C UART 12 SPI_A_MISO: GPIO SPI 13 I2C_EE_M1_S: GPIO I2C SPI 14 GND: 15 SARADC_CH1: 16 I2C_EE_M1_S: GPIO I2C SPI 17 3V3: 18 SPI_A_MOSI,: GPIO SPI PWM 19 SPI_B_MOSI: GPIO SPI 20 GND: 21 SPI_B_MISO: GPIO SPI 22 GPIOC_7: GPIO 23 I2C_EE_M1_S: GPIO I2C SPI UART 24 UART_EE_C_R: GPIO I2C SPI UART 25 GND: 26 SARADC_CH2: 27 I2C_AO_M0_S: GPIO I2C UART 28 I2C_AO_M0_S: GPIO I2C UART 29 NC: 30 GND: 31 NC: 32 GPIOAO_4: GPIO 33 NC: 34 GND: 35 UART_AO_B_T: GPIO UART 36 GPIOH_8: GPIO 37 UART_AO_B_R: GPIO UART 38 GPIOAO_10: GPIO 39 GND: 40 PWMAO_A: GPIO PWM
root@rockpis:~# mraa-gpio set 40 1 #pin40 pull high root@rockpis:~# mraa-gpio set 40 0 #pin40 pull low
PWM test
Radxa Zero provides 2 PWM devices: PWM_C and PWMAO_A. It is required to enable them at the same time if you want PWM function.
First, modify /boot/uEnv.txt overlays option as follows:
rock@zero:~$ cat /boot/uEnv.txt verbosity=7 console=ttyAML0,115200 overlay_prefix=meson rootfstype=ext4 fdtfile=amlogic/meson-g12a-radxa-zero.dtb overlays=meson-g12a-uart-ao-a-on-gpioao-0-gpioao-1 meson-g12a-pwm-c-on-gpiox-8 meson-g12a-pwmao-a-on-gpioao-11 rootuuid=bbe0631f-bbed-4033-8f75-fa5930deceed initrdsize=0xf1ee3e kernelversion=5.10.69-5-amlogic-gfeede6ac474e initrdimg=initrd.img-5.10.69-5-amlogic-gfeede6ac474e kernelimg=vmlinuz-5.10.69-5-amlogic-gfeede6ac474e
Reboot to apply the change.
Modify the macro PWM in /home/rock/mraa-examples/pwm.c as follows to test PWM_C. To test PWMAO_A, change #define PWM 18 to #define PWM 40.
/* PWM declaration */ #define PWM 18
Save and compile pwm.c:
rock@zero:~/mraa-examples$ gcc -o pwm pwm.c -lmraa rock@zero:~/mraa-examples$ sudo ./pwm PWM value is 0.010015 PWM value is 0.019985 PWM value is 0.030000 PWM value is 0.040014 PWM value is 0.049984 PWM value is 0.059999
I2C test
Radxa Zero provides 3 I2C devices: I2C1, I2C3, and I2C4.
Unlike PWM, if you need the I2C function, you can turn them on separately.
First, modify /boot/uEnv.txt overlays option as follows:
rock@zero:~$ cat /boot/uEnv.txt verbosity=7 console=ttyAML0,115200 overlay_prefix=meson rootfstype=ext4 fdtfile=amlogic/meson-g12a-radxa-zero.dtb overlays=meson-g12a-uart-ao-a-on-gpioao-0-gpioao-1 meson-g12a-i2c-ee-m1-gpioh-6-gpioh-7 rootuuid=bbe0631f-bbed-4033-8f75-fa5930deceed initrdsize=0xf1ee3e kernelversion=5.10.69-5-amlogic-gfeede6ac474e initrdimg=initrd.img-5.10.69-5-amlogic-gfeede6ac474e kernelimg=vmlinuz-5.10.69-5-amlogic-gfeede6ac474e
We use MPU6050 example to test I2C. Modify the macro MPU6050 in /home/rock/mraa-examples/i2c_mpu6050.c as follows to test I2C1.
/* mraa header */ #include "mraa/i2c.h" #define I2C_BUS 0
rock@zero:~/mraa-examples$ gcc -o i2c_mpu6050 i2c_mpu6050.c -lmraa
rock@zero:~/mraa-examples$ sudo ./i2c_mpu6050
accel: x:0 y:0 z:0
gyro: x:-10 y:1 z:7
accel: x:0 y:0 z:0
gyro: x:107 y:-12 z:69
accel: x:0 y:0 z:0
gyro: x:6 y:136 z:-50
accel: x:0 y:0 z:0
gyro: x:-5 y:48 z:-103
accel: x:0 y:0 z:0
gyro: x:3 y:3 z:5
UART test
Radxa Zero provides 3 UART devices: uart0, uart1, and uart4.
Like I2C, you can turn them on separately.
First, disable console and enable uart0 for uart test. Pay attention to ovelays and console options in below file:
rock@zero:~$ cat /boot/uEnv.txt verbosity=7 console=ttyAML0,115200 overlay_prefix=meson rootfstype=ext4 fdtfile=amlogic/meson-g12a-radxa-zero.dtb overlays=meson-g12a-uart-ao-a-on-gpioao-0-gpioao-1 meson-g12a-uart-ao-b-on-gpioao-2-gpioao-3 console= rootuuid=bbe0631f-bbed-4033-8f75-fa5930deceed initrdsize=0xf1ee3e kernelversion=5.10.69-5-amlogic-gfeede6ac474e initrdimg=initrd.img-5.10.69-5-amlogic-gfeede6ac474e kernelimg=vmlinuz-5.10.69-5-amlogic-gfeede6ac474e
Here we set console to NULL.
Reboot to apply the change. While waiting for system to boot up, you can use a jumper wire to short uart0's RX and TX pin, referring to this table if you don't know which pins you need to connect.
In another computer, start 2 SSH sessions, one for sending and one for receiving data via uart0.
Let's first start the receiving end, so it can wait for data input:
rock@zero:~$ sudo mraa-uart dev 0 baud 1500000 recv 1000
In another SSH session, run following command to send data:
rock@zero:~$ sudo mraa-uart dev 0 baud 1500000 send radxa
You should be able to see radxa shown in your first session.
SPI test
Change overlays in /boot/uEnv.txt and reboot:
rock@zero:~$ cat /boot/uEnv.txt verbosity=7 console=ttyAML0,115200 overlay_prefix=meson rootfstype=ext4 fdtfile=amlogic/meson-g12a-radxa-zero.dtb overlays=meson-g12a-uart-ao-a-on-gpioao-0-gpioao-1 meson-g12a-spi-spidev param_spidev_spi_bus=0 param_spidev_max_freq=10000000 rootuuid=bbe0631f-bbed-4033-8f75-fa5930deceed initrdsize=0xf1ee3e kernelversion=5.10.69-5-amlogic-gfeede6ac474e initrdimg=initrd.img-5.10.69-5-amlogic-gfeede6ac474e kernelimg=vmlinuz-5.10.69-5-amlogic-gfeede6ac474e
Create file test-spi.c with following content and build:
rock@zero:~/mraa-examples$ cat test-spi.c
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
/* mraa header */
#include "mraa/spi.h"
/* SPI declaration */
#define SPI_BUS 0
/* SPI frequency in Hz */
#define SPI_FREQ 10000000
int
main(int argc, char** argv)
{
mraa_result_t status = MRAA_SUCCESS;
mraa_spi_context spi;
int i, j;
/* initialize mraa for the platform (not needed most of the times) */
mraa_init();
//! [Interesting]
/* initialize SPI bus */
spi = mraa_spi_init(SPI_BUS);
if (spi == NULL) {
fprintf(stderr, "Failed to initialize SPI\n");
mraa_deinit();
return EXIT_FAILURE;
}
/* set SPI frequency */
status = mraa_spi_frequency(spi, SPI_FREQ);
if (status != MRAA_SUCCESS)
goto err_exit;
/* set big endian mode */
status = mraa_spi_lsbmode(spi, 0);
if (status != MRAA_SUCCESS) {
goto err_exit;
}
j = 10;
while(j) {
j--;
printf("0x%x\n",mraa_spi_write(spi, 0xaa));
}
err_exit:
mraa_result_print(status);
/* stop spi */
mraa_spi_stop(spi);
/* deinitialize mraa for the platform (not needed most of the times) */
mraa_deinit();
return EXIT_FAILURE;
}
rock@zero:~/mraa-examples$ gcc -o test-spi test-spi.c -lmraa
Then short PIN12 and PIN18 and run test-spi:
rock@zero:~/mraa-examples$ sudo ./test-spi 0xaa 0xaa 0xaa 0xaa 0xaa 0xaa 0xaa 0xaa 0xaa 0xaa MRAA: SUCCESS
Development
You can find libmraa's documentation here.