Hi all
I have a need to use SPI0 on my board.
How do I enable SPI0 support?
besides this, I need the ability to switch from Spi mode to GPIO mode in user space
Hi georgiy.lutsenko,
Are you using the devkit or custom board for Jetson Nano? with SD or eMMC module?
It would appear after you load spi driver through modprobe spidev.
Hi
I have both versions (SD or eMMC). And I’m using the latest version of jetpack for that platform.
how to find out device matching from /dev/spi
I also wanted to know about examples
Hi
I can’t figure out how the pins matchJetson Nano Hardware Design Documentation ) in which pinmux discribe, but why are there two columns for spi, and one column for matching with 40 pins header
You could configure the kernel config to enable it.
CONFIG_SPI_SPIDEV=y
You could check the device tree for SPI and also the carrier board specification for the details of SPI pins.
Which SPI would you like to use?
Left column(Module Pin) counts from SPI0, right column(Tegra X1 Signal) counts from SPI1.
For this SPI0, you could refer to spi0: spi@7000d400 in device tree.
Are there any official examples from nvidia in C/C++?
would it be ok to use this library?
For the name of 40-header pins, it is SPI1.spi@7000d400 address.
I looked through this topic and did not find any links to official libraries from Nvidia, is this true?
The only link that might help is this:
// SPDX-License-Identifier: GPL-2.0-only
/*
* SPI testing utility (using spidev driver)
*
* Copyright (c) 2007 MontaVista Software, Inc.
* Copyright (c) 2007 Anton Vorontsov <avorontsov@ru.mvista.com>
*
* Cross-compile with cross-gcc -I/path/to/cross-kernel/include
*/
#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <getopt.h>
#include <fcntl.h>
#include <time.h>
#include <sys/ioctl.h>
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Did I understand correctly?
And in this example the following path to the device is indicated:
Here’s what I have on my system:
and here’s what’s in the device tree:
SPI0[89,91,93,95] matches spidev0.0?
Yes, it is open source and you could use it to verify with SPI loopback test.
spidev0.0 and spidev0.1, it depends on which CS pin you are using.
thanks for answers
I’m currently working on running this example and I’m running into another problem.
Hi all
#include <iostream>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>
int main()
{
int fd;
int ret = 0;
const char *device = "/dev/spidev0.0";
uint8_t mode = SPI_MODE_0;
uint32_t speed = 500000;
fd = open(device, O_RDWR);
if (fd < 0) {
std::cerr << "Could not open SPI device." << std::endl;
return -1;
}
ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
if (ret == -1) {
std::cerr << "Could not set SPI mode." << std::endl;
close(fd);
return -1;
}
ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
if (ret == -1) {
std::cerr << "Could not set SPI speed." << std::endl;
close(fd);
return -1;
}
uint8_t tx[] = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
uint8_t rx[sizeof(tx)] = { 0 };
struct spi_ioc_transfer tr = {
.tx_buf = (unsigned long)tx,
.rx_buf = (unsigned long)rx,
.len = sizeof(tx),
.speed_hz = speed,
.delay_usecs = 0,
.bits_per_word = 8,
};
while(1) {
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret == -1) {
std::cerr << "SPI transmission failed." << std::endl;
close(fd);
return -1;
} else {
std::cout << "ret = " << ret << std::endl;
}
usleep(100000);
}
close(fd);
return 0;
}
the code compiles and runs but I don’t get anything in the output
maybe I did something wrong?
maybe it’s worth using this library?
/* Usage example of the JETGPIO library
* Compile with: gcc -Wall -o spi_loop spi_loop.c -ljetgpio
* Execute with: sudo ./spi_loop
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <jetgpio.h>
int main(int argc, char *argv[])
{
int Init;
int SPI_init;
int SPI_stat;
char tx[7] = {0,};
char rx[7] = {0,};
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Or do you not recommend it?
I checked pins with the program running using this command:
and I don’t see anyone using these pins
What can you recommend?
