I am unable to interface mcp 3008 with beaglebone green.trying to set communication in mode 0(CPOL =0 CPHA=0),the built in frequency in dts is set to 1Mhz.
things I have tried
1.enable device tree BB-SPI0-MCP3008-00A0.dts
on execution of
ls -al /dev/spidev1.*
I got
crw-rw---- 1 root spi 153, 0 Oct 7 16:40 /dev/spidev1.1
2.on execution of
cat /sys/kernel/debug/pinctrl/44e10800.pinmux/pingroups
group: pinmux_bb_spi0_pins pin 84 (PIN84) pin 85 (PIN85) pin 86 (PIN86) pin 87 (PIN87)
My reference code is as follow
#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>
#define ARRAY_SIZE(array) sizeof(array) / sizeof(array[0])
static const char *DEVICE = "/dev/spidev1.1";
static uint8_t MODE = SPI_MODE_0;
static uint8_t BITS = 8;
static uint32_t CLOCK = 1000000;
static uint16_t DELAY = 5;
/* * Ensure all settings are correct for the ADC */
static int prepare(int fd)
{
if (ioctl(fd, SPI_IOC_WR_MODE, &MODE) == -1)
{
perror("Can't set MODE"); return -1;
}
if (ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &BITS) == -1)
{
perror("Can't set number of BITS");
return -1;
}
if (ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &CLOCK) == -1)
{
perror("Can't set write CLOCK");
return -1;
}
if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &CLOCK) == -1)
{
perror("Can't set read CLOCK"); return -1;
}
return 0;
}
/* * (SGL/DIF = 0, D2=D1=D0=0) */
uint8_t control_bits_differential(uint8_t channel)
{
return (channel & 7) << 4;
}
/* * (SGL/DIF = 1, D2=D1=D0=0) */
uint8_t control_bits(uint8_t channel)
{
return 0x8 | control_bits_differential(channel);
}
/* * Given a prep'd descriptor, and an ADC channel, fetch the * raw ADC
value for the given channel. */
int readadc(int fd, uint8_t channel)
{
uint8_t tx[] = {1, control_bits(channel), 0
};
uint8_t rx[3]={0,0,0};
struct spi_ioc_transfer tr = {
.tx_buf = (unsigned long)tx,
.rx_buf = (unsigned long)rx,
.len = ARRAY_SIZE(tx),
.delay_usecs = DELAY,
.speed_hz = CLOCK,
.bits_per_word = BITS, };
if (ioctl(fd, SPI_IOC_MESSAGE(1), &tr) == 1)
{
perror("IO Error");
abort();
}
return ((rx[1] << 8) & 0x300) | (rx[2] & 0xFF);
}
int main(int argc, char **argv)
{
int fd = open(DEVICE, O_RDWR);
if (fd <= 0)
{
printf("Device %s not found\n", DEVICE);
return -1;
}
if (prepare(fd) == -1)
{ return -1; }
uint8_t i,radc=0;
for(i = 0;i < 8;i++)
{ printf("Channel %d: %d\n", i + 1, readadc(fd, i)); }
close(fd);
return 0;
}
after executing this code I am getting 1023 count for any applied voltage,where I am expecting count 0 for 0 input voltage and so on .
Can anybody please help me? can you tell me where I am doing wrong?what are the other things I have to consider while using SPI on beaglebone?any kind of help will be greatly appreciated!
solved it as suggested from other forum it was hardware related thing.I have to put 0.1uf capacitor between vcc and gnd,where analog ground and digital ground were common.
Related
I'm writing a Linux KVM hypervisor for x86 16-bit guests running in real mode. When doing interrupt calls (int ... instruction), I've encountered the KVM_INTERNAL_ERROR_SIMUL_EX error on Linux kernel 3.13.0. The same code is running fine on Linux kernel 3.16.0. Am I missing something? Is there a workaround I can add to my code to make it work with Linux kernel 3.13.0 (and possibly earlier)?
The test guest calls int 0x18 ... int 0x4f, all of which is handled in the hypervisor (C code after KVM_RUN has returned). When it's working correctly, all of the interrupt calls work. On Linux kernel 3.13.0, int 0x21 starts failing (and then int 0x22, int 0x23 and int 0x24 would also fail).
I was trying to write the shortest example C code to demonstrate the problem, here it is:
/* Based on: https://gist.github.com/zserge/d68683f17c68709818f8baab0ded2d15
* Based on: https://gist.githubusercontent.com/zserge/d68683f17c68709818f8baab0ded2d15/raw/b79033254b092ec9121bb891938b27dd128030d7/kvm-host-simple.c
*
* Compile: gcc -ansi -pedantic -s -O2 -W -Wall -o kvm16 kvm16.c && ./kvm16
*
* Expected correct output (e.g. on Linux 3.16.0 compiled for i386 (i686)):
*
* ...
* info: int 0x4f iret to: ...
* info: success, exiting
*
* Failure output (e.g. on Linux 3.13.0 compiled for amd64 (x86_64)):
*
* info: int 0x20 iret to: cs=0x0070 ip=0x0013
* fatal: KVM internal error suberror=2
*
* // Encounter unexpected simultaneous exceptions.
* #define KVM_INTERNAL_ERROR_SIMUL_EX 2
*/
#define _GNU_SOURCE
#include <fcntl.h>
#include <linux/kvm.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <unistd.h>
#define INT_NUM 0x21 /* Also works for INT_NUM == 0x20. */
int main(int argc, char *argv[]) {
int kvm_fd, vm_fd, vcpu_fd;
void *mem;
struct kvm_userspace_memory_region region;
struct kvm_run *run;
struct kvm_regs regs;
struct kvm_sregs sregs;
(void)argc; (void)argv;
if ((kvm_fd = open("/dev/kvm", O_RDWR)) < 0) {
perror("failed to open /dev/kvm");
return 1;
}
if ((vm_fd = ioctl(kvm_fd, KVM_CREATE_VM, 0)) < 0) {
perror("failed to create vm");
return 1;
}
if ((mem = mmap(NULL, 0x1000, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0)) == NULL) {
perror("mmap");
return 1;
}
memset(®ion, 0, sizeof(region));
region.slot = 0;
region.guest_phys_addr = 0;
region.memory_size = 0x1000;
region.userspace_addr = (uintptr_t)mem;
if (ioctl(vm_fd, KVM_SET_USER_MEMORY_REGION, ®ion) < 0) {
perror("KVM_SET_USER_MEMORY_REGION");
return 1;
}
{ /* 8086 real mode machine code. */
char *p = (char*)mem + 0x700;
unsigned int_num;
for (int_num = 0; int_num < 0x100; ++int_num) {
*(unsigned short*)((char*)mem + int_num * 4) = int_num; /* Interrupt vector INT_NUM offset := INT_NUM. */
*(unsigned short*)((char*)mem + int_num * 4 + 2) = 0x54; /* Interrupt vector INT_NUM segment := 0x54. */
}
*p++ = (char)0xf4; /* hlt. */
for (int_num = 0x18; int_num < 0x50; ++int_num) {
*p++ = (char)0xcd; /* int int_num. */
*p++ = (char)int_num;
}
*p++ = (char)0xf4;
}
memset((char*)mem + 0x540, '\xf4', 0x100); /* 256 times hlt. Interrupt vectors point here. */
if ((vcpu_fd = ioctl(vm_fd, KVM_CREATE_VCPU, 0)) < 0) {
perror("KVM_CREATE_VCPU");
return 1;
}
{
int kvm_run_mmap_size = ioctl(kvm_fd, KVM_GET_VCPU_MMAP_SIZE, 0);
if (kvm_run_mmap_size < 0) {
perror("KVM_GET_VCPU_MMAP_SIZE");
return 1;
}
run = (struct kvm_run *)mmap(
NULL, kvm_run_mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, vcpu_fd, 0);
if (run == NULL) {
perror("mmap kvm_run");
return 1;
}
}
memset(®s, '\0', sizeof(regs));
if (ioctl(vcpu_fd, KVM_GET_SREGS, &sregs) < 0) {
perror("KVM_GET_SREGS");
return 1;
}
{
int fd = open("kvm16.sregs", O_CREAT | O_WRONLY | O_TRUNC, 0644);
if (fd < 0) {
perror("open");
return 1;
}
if (write(fd, &sregs, sizeof(sregs)) != sizeof(sregs)) {
perror("write");
return 1;
}
if (close(fd) != 0) {
perror("close");
return 1;
}
}
sregs.cs.base = (sregs.cs.selector = 0x70) << 4;
sregs.ds.base = (sregs.ds.selector = sregs.cs.selector) << 4;
sregs.es.base = (sregs.es.selector = sregs.cs.selector) << 4;
sregs.ss.base = (sregs.ss.selector = sregs.cs.selector) << 4;
if (ioctl(vcpu_fd, KVM_GET_REGS, ®s) < 0) {
perror("KVM_GET_REGS");
return 1;
}
regs.rflags = 1 << 1; /* Reserved bit in EFLAGS. Even needed after KVM_GET_REGS. */
regs.rip = 0;
regs.rsp = 0x1000 - 0x700;
if (ioctl(vcpu_fd, KVM_SET_SREGS, &sregs) < 0) {
perror("KVM_SET_SREGS");
return 1;
}
if (ioctl(vcpu_fd, KVM_SET_REGS, ®s) < 0) {
perror("KVM_SET_REGS");
return 1;
}
for (;;) {
int ret = ioctl(vcpu_fd, KVM_RUN, 0);
unsigned short cs, ip;
if (ret < 0) {
perror("KVM_RUN");
return 1;
}
if (ioctl(vcpu_fd, KVM_GET_SREGS, &sregs) < 0) {
perror("KVM_GET_SREGS");
return 1;
}
if (ioctl(vcpu_fd, KVM_GET_REGS, ®s) < 0) {
perror("KVM_GET_REGS");
return 1;
}
cs = sregs.cs.selector;
ip = regs.rip;
if (run->exit_reason == KVM_EXIT_HLT) {
fprintf(stderr, "info: hlt: cs=0x%04x ip=0x%04x\n", cs, ip - 1);
if (cs == 0x70) {
if (ip != 0 + 1) {
fprintf(stderr, "info: success, exiting\n");
return 0; /* EXIT_SUCCESS after the second `hlt' in the code. */
}
} else if (cs == 0x54) { /* Simulate iret. */
const char *csip_ptr = (const char*)mem + ((unsigned short)sregs.ss.selector << 4) + (unsigned short)regs.rsp;
const unsigned short int_ip = ((const unsigned short*)csip_ptr)[0];
const unsigned short int_cs = ((const unsigned short*)csip_ptr)[1];
const unsigned short int_flags = ((const unsigned short*)csip_ptr)[2];
fprintf(stderr, "info: int 0x%02x iret to: cs=0x%04x ip=0x%04x\n", ip - 1, int_cs, int_ip);
sregs.cs.base = (sregs.cs.selector = int_cs) << 4;
regs.rip = int_ip;
if (int_flags & (1 << 9)) regs.rflags |= (1 << 9); /* Set IF back to 1 if it was 1. */
regs.rsp += 6; /* pop ip, pop cs, popfw . */
if (ioctl(vcpu_fd, KVM_SET_SREGS, &sregs) < 0) {
perror("KVM_SET_SREGS");
return 1;
}
if (ioctl(vcpu_fd, KVM_SET_REGS, ®s) < 0) {
perror("KVM_SET_REGS");
return 1;
}
} else {
fprintf(stderr, "fatal: unexpected hlt: cs=0x%04x ip=0x%04x\n", cs, ip - 1);
return 5;
}
} else if (run->exit_reason == KVM_EXIT_INTERNAL_ERROR) {
fprintf(stderr, "fatal: KVM internal error suberror=%d\n", (unsigned)run->internal.suberror);
return 4;
} else {
fprintf(stderr, "fatal: unexpected KVM exit: exit_reason=%d cs=0x%04x ip=0x%04x\n", run->exit_reason, cs, ip);
return 2;
}
}
}
#include <unistd.h> //Needed for I2C port
#include <fcntl.h> //Needed for I2C port
#include <sys/ioctl.h> //Needed for I2C port
#include <linux/i2c-dev.h> //Needed for I2C port
#include <stdio.h>
#include <time.h>
int file_i2c;
int length;
unsigned char buffer[60] = {0};
unsigned char cmdbuffer[60] = {0};
//PRINTS (SENSOR STATUS) IN BINARY
void printBin(unsigned char value)
{
for (int i = sizeof(char) * 7; i >= 0; i--) {
printf("%d", (value & (1 << i )) >> i);
}
putc('\n', stdout);
}
//CREATES DELAY IN MS
void delay(int milli)
{
long pause;
clock_t now,then;
pause = milli * (CLOCKS_PER_SEC / 1000);
now = then = clock();
while ((now-then) < pause) {
now = clock();
}
}
//TIMESTAMPS OUTPUT
void timestamp()
{
time_t ltime;
ltime=time(NULL);
printf("%s", asctime(localtime(<ime)));
}
//PORT SELECT FOR TCA9548A Addresses range from 0x70-0x77
void portSelect(int port, int addressTCA)
{
if (port > 7 || port < 0)
return;
if (ioctl(file_i2c, I2C_SLAVE, addressTCA) < 0) {
printf("Failed to acquire bus access and/or talk to slave.\n");
return;
}
cmdbuffer[0] = 1 << port;
length = 1;
write(file_i2c, cmdbuffer, length);
}
int main()
{
//----- OPEN THE I2C BUS -----
char *filename = (char*)"/dev/i2c-1";
if ((file_i2c = open(filename, O_RDWR)) < 0) {
//ERROR HANDLING: you can check errno to see what went wrong
printf("Failed to open the i2c bus");
return 0;
}
portSelect(1, 0x70);
//CONFIGURE SLAVE AND ATTEMPT CONNECTION
if (ioctl(file_i2c, I2C_SLAVE, 0x28) < 0) {
printf("Failed to acquire bus access and/or talk to slave.\n");
return 0;
}
flag:
cmdbuffer[0] = 0xAA;
cmdbuffer[1] = 0x00;
cmdbuffer[2] = 0x00;
length = 3;
if (write(file_i2c, cmdbuffer, length) != length)
//write() returns the number of bytes actually written, if it doesn't match then an error occurred (e.g. no response from the device)
{
printf("Failed to write to the i2c bus.\n"); //FAILS HERE
return 0;
}
length = 7; //<<< Number of bytes to read
if (read(file_i2c, buffer, length) != length)
//read() returns the number of bytes actually read, if it doesn't match then an error occurred (e.g. no response from the device)
{
printf("Failed to read from the i2c bus.\n");
} else {
//timestamp();
printf("Status:\n");
printBin(buffer[0]);
int pressure = (buffer[1] << 16) + (buffer[2] << 8) + buffer[3];
int temperature = (buffer[4] << 16) + (buffer[5] << 8) + buffer[6];
printf("Pressure : %d\n", pressure);
printf("Temperature : %d\n\n", temperature);
}
delay(5);
goto flag;
return 0;
}
Current code shown above. I am trying to read from 8 different Honeywell pressure sensors but for the moment I am just trying to get one working. I am able to read/write just fine without the multiplexer. Documentation is unhelpful as it only references Python or Arduino. I have scanned with console and confirmed the addresses of the sensors and mux.
Hey I am trying to write a user space application to move some data to an I2C for an embedded system running PetaLinux, an operating system for embedded Linux, although I do not think that is what is affecting the issue. I am getting a Connection timeout and a segmentation fault.
The function has macros that direct it to write to the first I2C bus. I specify the data that I want to write in main and pass it to i2c_write, which then passes it to i2c_ioctl_write.
Here is the code:
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#define I2C_ADAPTER "/dev/i2c-0"
#define I2C_DEVICE 0x00
#define REG_ADDR 0x00
int i2c_ioctl_write (int fd, uint8_t dev, uint8_t regaddr, uint16_t *data)
{
printf("i2c_ioctl_write\n");
int i, j = 0;
int ret;
uint8_t *buf;
buf = malloc(1 + 2 * (sizeof(data) / sizeof(data[0])));
if (buf == NULL) {
return -ENOMEM;
}
printf("\tBuffer Allocation Successful...\n");
buf[j ++] = regaddr;
for (i = 0; i < (sizeof(data) / sizeof(data[0])); i ++) {
buf[j ++] = (data[i] & 0xff00) >> 8;
buf[j ++] = data[i] & 0xff;
}
printf("\tBuffer Setup Successful...\n");
struct i2c_msg messages[] = {
{
.addr = dev,
.buf = buf,
.len = sizeof(buf) / sizeof(buf[0]),
},
};
printf("\tSetup I2C Messages...\n");
struct i2c_rdwr_ioctl_data payload = {
.msgs = messages,
.nmsgs = sizeof(messages) / sizeof(messages[0]),
};
printf("\tSetup I2C IOCTL Payload...\n");
ret = ioctl(fd, I2C_RDWR, &payload);
printf("\tWrote with IOCTL...\n");
if (ret < 0) {
ret = -errno;
}
free (buf);
return ret;
}
int i2c_ioctl_smbus_write (int fd, uint8_t dev, uint8_t regaddr, uint16_t *data)
{
printf("i2c_ioctl_smbus_write\n");
int i, j = 0;
int ret;
uint8_t *buf;
buf = malloc(2 * (sizeof(data) / sizeof(data[0])));
if (buf == NULL) {
return -ENOMEM;
}
for (i = 0; i < (sizeof(data) / sizeof(data[0])); i ++) {
buf[j ++] = (data[i] & 0xff00) >> 8;
buf[j ++] = data[i] & 0xff;
}
struct i2c_smbus_ioctl_data payload = {
.read_write = I2C_SMBUS_WRITE,
.size = I2C_SMBUS_WORD_DATA,
.command = regaddr,
.data = (void *) buf,
};
ret = ioctl (fd, I2C_SLAVE_FORCE, dev);
if (ret < 0)
{
ret = -errno;
goto exit;
}
ret = ioctl (fd, I2C_SMBUS, &payload);
if (ret < 0)
{
ret = -errno;
goto exit;
}
exit:
free(buf);
return ret;
}
int i2c_write (int fd, uint8_t dev, uint8_t regaddr, uint16_t *data)
{
printf("i2x_write\n");
uint64_t funcs;
if (ioctl(fd, I2C_FUNCS, &funcs) < 0) {
return -errno;
}
if (funcs & I2C_FUNC_I2C) {
return i2c_ioctl_write (fd, dev, regaddr, data);
} else if (funcs & I2C_FUNC_SMBUS_WORD_DATA) {
return i2c_ioctl_smbus_write (fd, dev, regaddr, data);
} else {
return -ENOSYS;
}
}
int main (int argc, char *argv[])
{
printf("main\n");
uint8_t regaddr;
int fd;
int ret = 0;
uint16_t data[] = {1, 2, 4};
fd = open(I2C_ADAPTER, O_RDWR | O_NONBLOCK);
ret = i2c_write(fd, I2C_DEVICE, REG_ADDR, data);
close(fd);
if (ret) {
fprintf (stderr, "%s.\n", strerror(-ret));
}
free(data);
return ret;
}
When I run the program on QEMU I get the following output:
main
i2x_write
i2c_ioctl_write
Buffer Allocation Successful...
Buffer Setup Successful...
Setup I2C Messages
Setup I2C IOCTL Payload
cdns-i2c e0004000.i2c: timeout waiting on completion
Wrote with IOCTL
Connection timed out.
Segmentation fault
I assume it is failing on the line
ret = ioctl(fd, I2C_RDWR, &payload);
but I am not sure why. Was the payload constructed improperly?
Update: Here is the current code:
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#define I2C_ADAPTER "/dev/i2c-0"
#define I2C_DEVICE 0x00
int main (int argc, char *argv[])
{
int fd;
int ret = 0;
fd = open(I2C_ADAPTER, O_RDWR | O_NONBLOCK);
uint64_t funcs;
int addr = 0X00;
if (ioctl(fd, I2C_SLAVE, addr) < 0) {
/* ERROR HANDLING; you can check errno to see what went wrong */
printf("Cannot setup as slave");
exit(1);
}
if (ioctl(fd, I2C_FUNCS, &funcs) < 0) {
printf("ioctl failed");
return -errno;
}
printf("funcs & I2C_FUNC_I2C: %llu\n", funcs & I2C_FUNC_I2C);
printf("funcs & I2C_FUNC_SMBUS_WORD_DATA: %llu\n", funcs & I2C_FUNC_SMBUS_WORD_DATA);
__u8 reg = 0x10;
__s32 res;
if (funcs & I2C_FUNC_I2C) {
char buf[10];
printf("Attempting to write to I2C bus via I2C protocol...\n");
buf[0] = reg;
buf[1] = 0x43;
buf[2] = 0x65;
int bytes_written = write(fd, buf, 3);
if(bytes_written != 3) {
printf("Wrote %d bytes", bytes_written);
printf("\tFailed to write to I2C Bus\n");
close(fd);
return -1;
}
else {
printf("\tSuccesful write to I2C Bus\n");
}
char buf2[10];
printf("Attempting to read from I2C bus via I2C protocol...\n");
if(read(fd, buf2, 1) != 1) {
printf("\tFailed to do I2C read from Bus\n");
close(fd);
return -1;
}
else {
printf("\tRead successful. Comparing read results from original write buffer...");
printf("\t\tWritten value: %c", buf[0]);
printf("\t\tRead value: %c", buf2[0]);
}
return 0;
} else if (funcs & I2C_FUNC_SMBUS_WORD_DATA) {
printf("Attempting to write to I2C bus via SMBus protocol...\n");
//res = i2c_smbus_write_word_data(fd, REG_ADDR, 0x6543);
res = 1;
if(res < 0) {
printf("\tFailed to write to I2C Bus\n");
close(fd);
return -1;
}
else {
printf("\tSuccesful write to I2C Bus\n");
}
//res = i2c_smbus_read_word_data(fd, REG_ADDR);
if(res < 0) {
printf("\tFailed to read from I2C Bus\n");
close(fd);
return -1;
}
else {
printf("\tRead successful. Comparing read results from original write buffer...");
printf("\t\tWritten value: %c", 0x6543);
printf("\t\tRead value: %c", res);
}
} else {
printf("Cannot write to I2C");
return -ENOSYS;
}
close(fd);
if (ret) {
fprintf (stderr, "%s.\n", strerror(-ret));
}
return ret;
}
I was able to get rid of the seg fault by removing free(), so thanks there. I have pinpointed the exact issue of the timeout which occurs in the Cadence I2C Driver here:
https://github.com/Xilinx/linux-xlnx/blob/3f3c7b60919d56119a68813998d3005bca501a40/drivers/i2c/busses/i2c-cadence.c#L825
which is still occurring.
As mentioned, there is probably some issue with the way I am writing to slave causing the slave to not send ACK, resulting in a timeout. I am not sure which registers I will need to write what to. I have a feeling the I2C_DEVICE macro and addr and reg variables will need to be changed.
cdns-i2c e0004000.i2c: timeout waiting on completion
It seems that i2c driver (cdns-i2s) doesnt recieves the acknowledgment from the slave. It may occur as you are using I2C-slave address as 0x00 which is a general call address. While using general call address the second byte that is sent has a special purpose which is mentioned in the i2c-specification (section 3.1.13).
If you use general call address you need to follow the specification or else Try using the exact i2c slave address instead of general call address(0x00).
I am trying to read one value from a memory location on the I2C bus after writing to it. I am getting strange output when I run it in the terminal.
Here is my program
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#define I2C_ADAPTER "/dev/i2c-0"
#define I2C_DEVICE 0x00
int main (int argc, char *argv[])
{
int file;
int addr = 0X00; /* XGPIOPS_DATA_LOW_OFFSET */
if((file = open(I2C_ADAPTER, O_RDWR)) < 0) {
printf("Failed to open the bus");
return -1;
}
if(ioctl(file, I2C_SLAVE, addr) < 0) {
printf("Unable to open device as slave %s", strerror(errno));
return -1;
}
char buf[10];
buf[0] = addr;
buf[1] = 0x10;
if(write(file, buf, 2) != 2) {
printf("Failed to write to bus %s.\n\n", strerror(errno));
}
else {
printf("Successful write\n");
printf(buf);
printf("\n\n");
}
if(read(file, buf, 2) != 2) {
printf("Failed to read from the i2c bus. %s\n\n", strerror(errno));
}
else {
printf("Successful read\n");
printf(buf);
printf("\n\n");
}
return 0;
}
The output from the program looks like this
Successful write
Successful read ��
On my terminal those blocks look more like question marks inside of diamonds. I am not sure what that corresponds to in ASCII.
Why am I not reading back that 0x10 which is the second byte after the address byte that I originally write?
Based on the first set of answers, here is the updated code:
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#define I2C_ADAPTER "/dev/i2c-0"
#define I2C_DEVICE 0x00
int main (int argc, char *argv[])
{
int file;
long addr, reg_addr;
char *end;
if(argc == 3) {
addr = strtol(argv[1], &end, 16);
printf("Value of addr is: %ld\n", addr);
reg_addr = strtol(argv[2], &end, 16);
printf("Value of reg_addr is: %ld\n", reg_addr);
}
else {
printf("arg failed\n\n.");
addr = 0x00;
}
if((file = open(I2C_ADAPTER, O_RDWR)) < 0) {
printf("Failed to open the bus\n");
return -1;
}
if(ioctl(file, I2C_SLAVE, addr) < 0) {
printf("Unable to open device as slave \n%s\n", strerror(errno));
return -1;
}
char buf[10];
buf[0] = addr;
buf[1] = reg_addr;
buf[2] = 0x10;
if(write(file, buf, 3) != 3) {
printf("Failed to write to bus %s.\n\n", strerror(errno));
}
else {
printf("Successful write\n");
printf(buf);
printf("\n\n");
}
if(read(file, buf, 3) != 3) {
printf("Failed to read from the i2c bus.\n %s\n\n", strerror(errno));
}
else {
printf("Successful read\n");
printf("Buf = [%02X,%02X,%02X]\n", buf[0], buf[1], buf[2]);
printf("\n\n");
}
return 0;
}
At this point, whenever I use 0x00 as the addr, I get FF, FF, FF as the output, no matter what argv[2] is. Here is the applicable part of the device tree file. Note that this is being emulated, so I cannot probe the physical device.
&i2c0 {
status = "okay";
clock-frequency = <400000>;
pinctrl-names = "default";
i2cswitch#74 {
compatible = "nxp,pca9548";
#address-cells = <1>;
#size-cells = <0>;
reg = <0x74>;
i2c#0 {
#address-cells = <1>;
#size-cells = <0>;
reg = <0>;
si570: clock-generator#5d {
#clock-cells = <0>;
compatible = "silabs,si570";
temperature-stability = <50>;
reg = <0x5d>;
factory-fout = <156250000>;
clock-frequency = <148500000>;
};
};
i2c#2 {
#address-cells = <1>;
#size-cells = <0>;
reg = <2>;
eeprom#54 {
compatible = "at,24c08";
reg = <0x54>;
};
};
i2c#3 {
#address-cells = <1>;
#size-cells = <0>;
reg = <3>;
gpio#21 {
compatible = "ti,tca6416";
reg = <0x21>;
gpio-controller;
#gpio-cells = <2>;
};
};
i2c#4 {
#address-cells = <1>;
#size-cells = <0>;
reg = <4>;
rtc#51 {
compatible = "nxp,pcf8563";
reg = <0x51>;
};
};
i2c#7 {
#address-cells = <1>;
#size-cells = <0>;
reg = <7>;
hwmon#52 {
compatible = "ti,ucd9248";
reg = <52>;
};
hwmon#53 {
compatible = "ti,ucd9248";
reg = <53>;
};
hwmon#54 {
compatible = "ti,ucd9248";
reg = <54>;
};
};
};
};
Here are a couple of example tests
Try to test the SiLabs clock generator
root#plnx_arm:~# /usr/bin/i2c-test-mem-location 0x54 0x00
Value of addr is: 84
Value of reg_addr is: 0
Unable to open device as slave
Device or resource busy
Try to test the eeprom device
root#plnx_arm:~# /usr/bin/i2c-test-mem-location 0x5d 0x00
Value of addr is: 93
Value of reg_addr is: 0
Unable to open device as slave
Device or resource busy
This is my program on the third try. After taking to mind the notes made in the answers, I have this written
#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#define I2C_ADAPTER "/dev/i2c-0"
#define DEVICE_ADDRESS 0x54
int main (int argc, char *argv[])
{
int file;
uint8_t reg, value;
char *end;
printf("The device address on the bus: %d", DEVICE_ADDRESS);
if(argc == 3) {
reg = strtol(argv[1], &end, 16);
printf("Value of register address: %d\n", reg);
value = strtol(argv[2], &end, 16);
printf("value to write is: %d\n", value);
}
else {
printf("arg failed\n\n.");
}
if((file = open(I2C_ADAPTER, O_RDWR)) < 0) {
printf("Failed to open the bus\n");
return -1;
}
if(ioctl(file, I2C_SLAVE, DEVICE_ADDRESS) < 0) {
printf("Unable to open device as slave \n%s\n", strerror(errno));
return -1;
}
char buf[10];
buf[0] = reg;
buf[1] = value;
if(write(file, buf, 2) != 2) {
printf("Failed to write to bus %s.\n\n", strerror(errno));
}
else {
printf("Successful write\n");
printf(buf);
printf("\n\n");
}
if(read(file, buf, 2) != 2) {
printf("Failed to read from the i2c bus.\n %s\n\n", strerror(errno));
}
else {
printf("Successful read\n");
printf("Buf = [%02X,%02X,%02X]\n", buf[0], buf[1], buf[2]);
printf("\n\n");
}
return 0;
}
Unfortunately, even still, I am getting the same error.
root#plnx_arm:~# /usr/bin/i2c-test-mem-location 0x00 0x10
The device address on the bus: 84Value of register address: 0
value to write is: 16
Unable to open device as slave
Device or resource busy
root#plnx_arm:~# /usr/bin/i2c-test-mem-location 0x30 0x10
The device address on the bus: 84Value of register address: 48
value to write is: 16
Unable to open device as slave
Device or resource busy
EDIT 2: I think you might not be setting your I2C device address correctly. What you have as your I2C_ADAPTER ("/dev/i2c-0") indicates which I2C bus the device is on. You aren't even using your I2C_DEVICE macro, but that's what you should be passing to your ioctl call (e.g. ioctl(file, I2C_SLAVE, I2C_DEVICE);) and it should be the I2C address of the device you want to access (e.g. 0x5D for the Clock Generator) instead of 0x00.
I also think your reads/writes are incorrect. Once you've specified the bus and device via open() and ioctl() you don't need to worry about those anymore. You only need to worry about the register you want to access (if your I2C device uses registers) and the actual data.
To write to your I2C device, assuming it uses a one-byte register, write a buffer of two bytes: The first is the register, the second is the value you want to write:
bool i2cdev_byte_write(int file, uint8_t reg, uint8_t val)
{
uint8_t bytes[2];
bytes[0] = reg;
bytes[1] = val;
/* Write the register followed by the value */
if (write(file, bytes, 2) != 2)
return false;
return true;
}
To read from your I2C device, assuming it uses a one-byte register, write a buffer of one byte (the register address) then read a buffer of one or more bytes (the value at that register and subsequent registers):
bool i2cdev_bytes_read(int file, uint8_t reg, unsigned int count, uint8_t *out_buf)
{
if (!out_buf)
return false;
/* Write the register */
if (write(file, ®, 1) != 1)
{
printf("Failed to write register value\n");
return false;
}
/* Read the specified number of bytes */
if (read(file, out_buf, count) != count)
{
printf("Failed to read from the i2c bus\n");
return false;
}
return true;
}
Again, note that all the above comments depend on it being an I2C device that uses a single-byte register address and that it supports auto-incrementing the register address when reading multiple bytes at a time. You'll need to check the datasheet for your I2C device to determine exactly how it needs to be accessed.
EDIT: This is a printf() newbie failure. You can't just try to printf an array of bytes. That's not how printf() works.
Try this:
printf("Buf = [%02X,%02X]\n", buf[0], buf[1]);
Also, as I wrote in my original response, you likely need to write the register address back out again prior to reading the register contents.
The i2c protocol requires that you specify a device address (i.e. 0x00) and a register address. You can then write the value (in your case, 0x10) to that register address. Try this instead:
char buf[10];
buf[0] = addr;
buf[1] = [REGISTER ADDRESS];
buf[2] = 0x10;
if(write(file, buf, 3) != 3) {
printf("Failed to write to bus %s.\n\n", strerror(errno));
}
else {
printf("Successful write\n");
printf("Addr: %02x Subaddr: %02x Value: %02x\n\n", buf[0], buf[1], buf[2]);
}
Once this write has been completed, you should be able to read with:
if(read(file, buf, 1) != 1) {
printf("Failed to read from the i2c bus. %s\n\n", strerror(errno));
}
else {
printf("Successful read\n");
printf("Value: %02x\n\n", buf[0]);
}
Based on the device tree, the address that needs to be fed to IOCtl is the i2cswitch mux address. This address is 0x74, which can be seen in the device tree. Opening the i2c-0 device file corresponds to the i2c0 entry in the device tree which is parent to the mux. When writing to EEPROM, the first byte in the buffer should be the device address, as mentioned by #AndrewCottrell. This address is 0x54. The second byte should be the data you want to write
#define I2C_ADAPTER "/dev/i2c-0"
#define I2C_SWITHC_MUX_ADDRESS 0x74
#define DEVICE_ADDRESS 0x54
...
file = open(I2C_ADAPTER, O_RDWR); /* Check for error */
ioctl(file, I2C_SLAVE_FORCE, I2C_SWITHC_MUX_ADDRESS); /* Check for error */
uint8_t reg, value;
reg = DEVICE_ADDRESS;
buf[0] = reg;
buf[1] = value;
write(file, buf, 2); /* Check for error */
read(file, buf, 1); /* Check for error */
/* buf[0] should be value*/
I also have problems reading data from the memory of an NTAG 5 boost component and I found this thread while looking for the reason for this problem. Indeed, for each I2C reading I do on the component, I receive the "FF" value. I didn't find the answer in this thread but maybe you answer my question in this thread.
I trying to read and write an Atmel 24C256 EEPROM with a Raspberry Pi B+ over I2C, but I'm having trouble getting it all to work right.
Here is the code I have so far:
#include <stdio.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <linux/i2c.h>
#define DEVICE_PATH "/dev/i2c-1"
#define PAGE_SIZE 64
#define DEVICE_ADDR 0x50 // 0b1010xxxx
int file_desc;
char buffer[PAGE_SIZE + 2]; // 64 bytes + 2 for the address
void teardownI2C()
{
int result = close(file_desc);
}
void setupI2C()
{
file_desc = open(DEVICE_PATH, O_RDWR);
if(file_desc < 0)
{
printf("%s\n", strerror(errno));
exit(1);
}
if(ioctl(file_desc, I2C_SLAVE, DEVICE_ADDR) < 0)
{
printf("%s\n", strerror(errno));
teardownI2C();
exit(1);
}
}
int write_to_device(char addr_hi, char addr_lo, char * buf, int len)
{
struct i2c_rdwr_ioctl_data msg_rdwr;
struct i2c_msg i2cmsg;
char my_buf[PAGE_SIZE + 2];
if(len > PAGE_SIZE + 2)
{
printf("Can't write more than %d bytes at a time.\n", PAGE_SIZE);
return -1;
}
int i;
my_buf[0] = addr_hi;
my_buf[1] = addr_lo;
for(i= 0; i < len; i++)
{
my_buf[2+i] = buf[i];
}
msg_rdwr.msgs = &i2cmsg;
msg_rdwr.nmsgs = 1;
i2cmsg.addr = DEVICE_ADDR;
i2cmsg.flags = 0;
i2cmsg.len = 2+len;
i2cmsg.buf = my_buf;
if(ioctl(file_desc,I2C_RDWR,&msg_rdwr)<0)
{
printf("write_to_device(): %s\n", strerror(errno));
return -1;
}
return 0;
}
int read_from_device(char addr_hi, char addr_lo, char * buf, int len)
{
struct i2c_rdwr_ioctl_data msg_rdwr;
struct i2c_msg i2cmsg;
if(write_to_device(addr_hi, addr_lo ,NULL,0)<0)
{
printf("read_from_device(): address reset did not work\n");
return -1;
}
msg_rdwr.msgs = &i2cmsg;
msg_rdwr.nmsgs = 1;
i2cmsg.addr = DEVICE_ADDR;
i2cmsg.flags = I2C_M_RD;
i2cmsg.len = len;
i2cmsg.buf = buf;
if(ioctl(file_desc,I2C_RDWR,&msg_rdwr)<0)
{
printf("read_from_device(): %s\n", strerror(errno));
return -1;
}
return 0;
}
void fill_buffer(char *buf)
{
int i = 0;
while(i < PAGE_SIZE && *buf)
{
buffer[i+2] = *buf++;
}
while(i++ < PAGE_SIZE-1)
{
buffer[i+2] = '*'; // fill the buffer with something
}
}
int main()
{
setupI2C(); //setup
fill_buffer("Here are some words.");
write_to_device(0x01, 0x00, buffer, PAGE_SIZE);
char newbuf[PAGE_SIZE];
if(read_from_device(0x01, 0x00, newbuf, PAGE_SIZE)>0)
{
printf("%s\n", newbuf);
}
teardownI2C(); //cleanup
return EXIT_SUCCESS;
}
Writing to the device like in the line write_to_device(0x01, 0x00, buffer, PAGE_SIZE); doesn't generate any errors but when I try to read from the device, I have to write a "dummy" byte according to the spec sheet and then try to read from the device but for some reason writing the dummy byte results in an error "Input/output error". I can't figure out how this works. I am using two resources to guide me, the Linux I2C-Dev documentation and an example from a similar EEPROM device. I'm sort of stuck here and don't know what to try. Any suggestions or pointers are greatly appreciated!
Alternatively, you could access it via the kernel at24.c driver, if you're able to compile and install a different kernel device tree for your Raspberry Pi.
The kernel device tree needs to specify the EEPROM's type and address, and which I²C bus it's connected to. I'm not sure about Raspberry Pi, but for the BeagleBone Black EEPROM it goes like this:
&i2c0 {
eeprom: eeprom#50 {
compatible = "at,24c32";
reg = <0x50>;
};
};
For your device you'd specify compatible = "at,24c256";
Ensure the kernel config specifies CONFIG_EEPROM_AT24=y (or =m).
Then you should be able to access the EEPROM memory from userspace at something like /sys/bus/i2c/devices/0-0050/eeprom or /sys/bus/i2c/drivers/at24/0-0050/eeprom.
maybe this here might help. http://www.richud.com/wiki/Rasberry_Pi_I2C_EEPROM_Program since it handles apparently the device you are trying to program and also explains some caveats of addressing 24c256
Craig McQueen's answer got me on the right track, but it is not easy to figure the whole thing out on your own.
Here is a AT24C256 device tree overlay that works for me on the Raspberry Pi:
/dts-v1/;
/plugin/;
/ {
fragment#0 {
target = <&i2c1>;
overlay {
pinctrl-names = "default";
pinctrl-0 = <&i2c1_pins>;
clock-frequency = <100000>;
status = "okay";
at24#50 {
compatible = "atmel,24c256","at24";
#address-cells = <1>;
#size-cells = <0>;
reg = <0x50>;
pagesize = <64>;
size = <32768>;
address-width = <16>;
};
};
};
};
Save it to "at24c256.dts", compile (might need to install the device tree compiler) it using:
dtc -O dtb -o at24c256.dtbo -b 0 -# at24c256.dts
and save it in "/boot/overlays". Then activate the overlay by adding:
dtparam=i2c_arm=on
dtoverlay=at24c256
to "/boot/config.txt" and reboot. You should now have a device file "/sys/class/i2c-dev/i2c-1/device/1-0050/eeprom" (if your I2C bus number is 1) which you can write to like a normal file.
Write to it using e.g.:
echo 'Hello World' | sudo tee /sys/class/i2c-dev/i2c-1/device/1-0050/eeprom
Read from it using e.g.:
sudo more /sys/class/i2c-dev/i2c-1/device/1-0050/eeprom
Not sure how you can get around the su-rights for accessing the device though. Adding the user to the i2c-group does not help...
Small and simple program to understand the easy management of an eeprom
/*
Simple program to write / read the eeprom AT24C32.
Developed and tested on the Raspberry pi3B jessie
To create the executable use the following command:
gcc -Wall -o thisprogram.exe thisprogram.c
*/
#include <stdio.h>
#include <sys/ioctl.h> // ioctl
#include <fcntl.h> // open
#include <unistd.h> // read/write usleep
#include <time.h>
#include <netinet/in.h> // htons
#include <linux/i2c-dev.h>
#pragma pack(1)
#define PAGESIZE 32
#define NPAGES 128
#define NBYTES (NPAGES*PAGESIZE)
#define ADDRESS 0x57 // AT24C32's address on I2C bus
typedef struct {
ushort AW;
char buf[PAGESIZE+2];
}WRITE;
static WRITE AT = {0};
int main() {
int fd;
char bufIN[180] = {0};
time_t clock=time(NULL);
snprintf(AT.buf, PAGESIZE+1, "%s: my first attempt to write", ctime(&clock)); // the buffer to write, cut to 32 bytes
if ((fd = open("/dev/i2c-1", O_RDWR)) < 0) { printf("Couldn't open device! %d\n", fd); return 1; }
if (ioctl(fd, I2C_SLAVE, ADDRESS) < 0) { printf("Couldn't find device on address!\n"); return 1; }
AT.AW = htons(32); // I will write to start from byte 0 of page 1 ( 32nd byte of eeprom )
if (write(fd, &AT, PAGESIZE+2) != (PAGESIZE+2)) { perror("Write error !"); return 1; }
while (1) { char ap[4]; if (read(fd,&ap,1) != 1) usleep(500); else break; } // wait on write's end
if (write(fd, &AT, 2) != 2) { perror("Error in sending the reading address"); return 1; }
if (read(fd,bufIN,PAGESIZE) != PAGESIZE) { perror("reading error\n"); return 1;}
printf ("\n%s\n", bufIN);
close(fd);
return 0;
}
My code:
enter code here
__s32 write_eeprom(__s32 fd,__u32 offset,__u32 len,__u8 *buf)
{
__s32 ret;
struct i2c_rdwr_ioctl_data msg_set;
struct i2c_msg iomsgs;
__u32 sended, sending;
__u8 temp[ONE_PAGE + 1];
if((offset + len) > BYTES_MAX || len == 0)
{
printf("write too long than BYTES_MAX\n");
return -1;
}
sended = 0;
iomsgs.addr = DEVICE_ADDR;
iomsgs.flags = 0; //write
iomsgs.buf = temp;
msg_set.msgs = &iomsgs;
msg_set.nmsgs = 1;
while(len > sended)
{
if(len - sended > ONE_PAGE)
sending = ONE_PAGE;
else
sending = len - sended;
iomsgs.len = sending + 1;
temp[0] = offset + sended;
memcpy(&temp[1], buf + sended, sending);
//printf("sending:%d sended:%d len:%d offset:%d \n", sending, sended, len, offset);
ret = ioctl(fd, I2C_RDWR, (unsigned long)&msg_set);
if(ret < 0)
{
printf("Error dring I2C_RDWR ioctl with error code: %d\n", ret);
return ret;
}
sended += sending;
usleep(5000);
}
return sended;
}