I am trying to interface with a Devantech digital compass found here -
http://www.acroname.com/robotics/parts/R117-COMPASS.html
I am using a i2c-usb converter to plug it into my laptop -
http://www.robot-electronics.co.uk/htm/usb_i2c_tech.htm
First of all, I do not know much about electrical engineering. I have a good idea of the bare basics, but after that I get lost.
I am trying to follow this tutorial -
https://xgoat.com/wp/2007/11/11/using-i2c-from-userspace-in-linux/
However I get stuck at the very beginning when I try to set the device address.
if( ioctl( fd, I2C_SLAVE, ADDRESS ) < 0 )
{
fprintf( stderr, "Failed to set slave address: %m\n" );
return 2;
}
returns "Failed to set slave address: Invalid argument"
I originally thought the address should be 0xC0 because a sentence in the manual for the compass reads "First send a start bit, the module address (0xC0)..." but that did not work.
Now I have a loop that just goes from 1 to 100 and tries each one for the address, but they all fail. The loop is -
for(int i=0x0;i<0x100;i++) {
if( ioctl( fd, I2C_SLAVE, i ) < 0 )
fprintf( stderr, "Failed to set slave address for address %i: %m\n", i );
}
I'm not sure what else to try. Right now, I just want to set the address so I can start attempting to read and write. Since the converter is what is actually connected to the pc, should I be using the address for that? And if so, where can I find it on that link with the information for it? If someone has an idea of what I could try or what is wrong that would be great.
EDIT:
Okay I have the code like this now -
#define ADDRESS 0x55
int fd = open("/dev/i2c-0", O_RDWR);
if (fd < 0) {
printf("\n<0, %m", errno);
return -1;
}
if( ioctl( fd, I2C_SLAVE, ADDRESS ) < 0 ) {
fprintf( stderr, "Failed to set slave address: %m\n" );
return 2;
}
if( i2c_smbus_write_byte( fd, 0xAA ) < 0 )
fprintf( stderr, "Failed to write 0xAA to I2C device: %m\n" );
It will set the address, but it won't write anything. Whenever I try to write to it, I get -
Failed to write 0xAA to I2C device: No such device or address
Why are your trying to send 0xAA to the device ?
To my understanding this is not a register for it (for the CMPS03, the only command is register 15 and its usage is not common: change the I2C address, factory reset, ...).
And 0x55 seems definitively not the address of the device ... 0xC0 should be the write one.
Could be that /dev/i2c-0 has not been created properly / is not correct?
How did you get /dev/ic2-0 created ?
Related
Edit: I solved UART communication problem but I have new problem getting pwm signal after receiving Transmit Data. I can blink led I can drive relay with transmitted data but I could not produce PWM signal.
maps(120, 1, 1, 250, RxData[4]);
ADC_Left = Yx; __HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_1,ADC_Left);
I used __HAL_TIM_SET_COMPARE function but it doesnt work. I can observe ADC_Left’s value on Debug site but its not work.
I am trying to realize UART communication between 2 stm32. I know there are several topic related with but my question focused another one.
I am reading 2 adc value on stm32 which is only transmit these value and other one only receive these 2 adc value. To do this
MX_USART1_UART_Init();
__HAL_UART_ENABLE_IT(&huart1, UART_IT_RXNE); // Interrupt Enable
__HAL_UART_ENABLE_IT(&huart1, UART_IT_TC);
char TxData1[10];
..............
TxData1[0] = 0xEA;
TxData1[1] = wData.Byte_1;
TxData1[2] = wData.Byte_2;
TxData1[3] = wData.Byte_3;
TxData1[4] = wData.Right_Adc_Val;
TxData1[5] = wData.Left_Adc_Val;
TxData1[6] = wData.Byte_6;
for(uint8_t i = 1 ; i < 7; i++)
{
wData.Checksum = wData.Checksum + TxData1[i];
}
wData.Checksum_H = (wData.Checksum >> 8)&0xFF;
wData.Checksum_L = (wData.Checksum)&0xFF;
TxData1[7] = wData.Checksum_H;
TxData1[8] = wData.Checksum_L;
TxData1[9] = 0xAE;
HAL_UART_Transmit_IT(&huart1,(uint8_t*) &TxData1,10);
............
This block sent them I can observate them on Debug screen and using TTL module's Tx Rx pins.
MX_USART1_UART_Init();
__HAL_UART_ENABLE_IT(&huart1, UART_IT_RXNE); // Interrupt Enable
__HAL_UART_ENABLE_IT(&huart1, UART_IT_TC);
char RxData[10];
while(1){
HAL_UART_Receive_IT(&huart1,(uint8_t*) &RxData,10);
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
if(huart->Instance == USART1)
{
HAL_UART_Receive_IT(&huart1,(uint8_t*) &RxData,10);
}
There is no problem up to here but when i getting RxData 0. index , it gives EA . Of course it should be give EA. When the adc data change all the ranking is changing. RxData[0] gives meaningless data. adc value is jumping over the all RxData array.
data locations must always be in the same index. How Can I get these data in stability for ex.
RxData[0]=EA
.
.
RxData[4]= should give adc value. so on.
..
Edit: I tried other mode of UART, DMA (in circular mode) and direct mode were used. I cant receive even 1 byte with DMA .
In your example code, you have an extra & that needs to be removed from both the transmit and receive HAL method calls. Example:
HAL_UART_Transmit_IT(&huart1,(uint8_t*) &TxData1,10);
HAL_UART_Transmit_IT(&huart1,(uint8_t*) TxData1,10);
To avoid this type of error in the future, recommend not using the cast and try something like the following:
uint8_t TxData1[10];
...
HAL_UART_Transmit_IT(&huart1, TxData1, sizeof(TxData1);
I'm starter of RTOS and I'm using Xenomai v2.6.3.
I'm trying to get some data using Serial communication.
I did my best on the task following the xenomai's guide and open sources, but it doesn't work well.
the link of the guide --> (https://xenomai.org//serial-16550a-driver/)
I just followed the sequence to use the module xeno_16550A. (with port io = 0x2f8 and irq=3)
I followed open source http://www.acadis.org/pages/captain.at/serial-port-example
It works well in write task, but read task doesn't work well.
It gave me the error sentence with error while RTSER_RTIOC_WAIT_EVENT, code -110 (it means connection timed out)
Moreover I checked the irq number3 by typing command 'cat /proc/xenomai/irq', but the interrupt number doesn't increase.
In my case, I don't need to write data, so I erase the write task code.
The read task proc is follow
void read_task_proc(void *arg) {
int ret;
ssize_t red = 0;
struct rtser_event rx_event;
while (1) {
/* waiting for event */
ret = rt_dev_ioctl(my_fd, RTSER_RTIOC_WAIT_EVENT, &rx_event );
if (ret) {
printf(RTASK_PREFIX "error while RTSER_RTIOC_WAIT_EVENT, code %d\n",ret);
if (ret == -ETIMEDOUT)
continue;
break;
}
unsigned char buf[1];
red = rt_dev_read(my_fd, &buf, 1);
if (red < 0 ) {
printf(RTASK_PREFIX "error while rt_dev_read, code %d\n",red);
} else {
printf(RTASK_PREFIX "only %d byte received , char : %c\n",red,buf[0]);
}
}
exit_read_task:
if (my_state & STATE_FILE_OPENED) {
if (!close_file( my_fd, READ_FILE " (rtser)")) {
my_state &= ~STATE_FILE_OPENED;
}
}
printf(RTASK_PREFIX "exit\n");
}
I could guess the causes of the problem.
buffer size or buffer is already full when new data is received.
rx_interrupt doesn't work....
I want to check whether the two things are wrong or not, but How can I check?
Furthermore, does anybody know the cause of the problem? Please give me comments.
I have an Arduino connected over USB with a Raspberry Pi. A Python program is sending a value over USB, then the arduino receives it and turns the LED on. The Arduino is sending a analogue value from A0 to the Python program on the Raspberry. But Python receives sometimes 024, 24 or 4 instead of 1024. How can I fix this? Here is my code:
http://www.bitsharr.com/Hsoxw7nG
Arduino Code:
int led = 13;
char charIn;
int sensorPin = A0; // select the input pin for the potentiometer
int sensorValue = 0; // variable to store the value coming from the sensor
long previousMillis = 0;
long interval = 1000;
// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(led, OUTPUT);
Serial.begin(9600); //This initializes the USB as a serial port
}
void loop() {
if (Serial.available()) {
delay(5); // warten bis alle Daten da sind
while(Serial.available() > 0) {
charIn =(char) Serial.read();
if (charIn == '1') {
digitalWrite(led,HIGH);
delay(5000);
digitalWrite(led,LOW);
}
}
}
Python Code:
#!/usr/bin/python
# -*- coding: utf-8 -*-
from serial import Serial
ser = Serial('/dev/ttyUSB0', 9600)
x=ser.readline()
ser.write('1')
print(x)
def cleanup( str ):
result = ""
for c in str:
if( (c >= "0") and (c <= "9") ):
result += c
return result
print( cleanup(x))
#ser.write("1")
sensorValue = analogRead(sensorPin); //Reads the voltage of the resistor.
Serial.println(sensorValue); //Writes the voltage on the Serial port.
}
For starters, you are using Arduino code in your Python code.
sensorValue = analogRead(sensorPin); //Reads the voltage of the resistor.
Serial.println(sensorValue); //Writes the voltage on the Serial port.
How would your computer know what values are on your Arduino? You need to move this into the Arduino code. I can't tell you where: you never specified exactly what you want to accomplish with this code.
Some more problems with your code:
#ser.write("1") should be ser.write("1")
These two lines aren't bad but they're a bad coding practice to include because you don't use them:
long previousMillis = 0;
long interval = 1000;
But python receives sometimes 024, 24 or 4 instead of 1024.
The Arduino never sent anything; there is no serial.print(); or serial.println();! I don't know how you are receiving data. If you make the edits to your code above and/or specify exactly what you want to do (i.e. Send a 1 to the Arduino, turn a LED on, get sensor data back every five seconds, if the data is above 50%, turn the light off) and still don't know what to do, feel free to comment for clarification.
I have used the ICMP example provided in the ASIO documentation to create a simple ping utility. However, the example covers IPv4 only and I have a hard time to make it work with IPv6.
Upgrading the ICMP header class to support IPv6 requires a minor change - the only difference between ICMP and ICMPv6 header is the different enumeration of ICMP types. However, I have a problem computing the checksum that needs to be incorporated in the ICMPv6 header.
For IPv4 the checksum is based on the ICMP header and payload. However, for IPv6 the checksum should include the IPv6 pseudo-header before the ICMPv6 header and payload. The ICMPv6 checksum function needs to know the source and destination address that will be in the IPv6 header. However, we have no control over what goes into the IPv6 header. How can this be done in Asio-Boost?
For reference please find below the function for IPv4 checksum calculation.
void compute_checksum(icmp_header& header, Iterator body_begin, Iterator body_end)
{
unsigned int sum = (header.type() << 8) + header.code()
+ header.identifier() + header.sequence_number();
Iterator body_iter = body_begin;
while (body_iter != body_end)
{
sum += (static_cast<unsigned char>(*body_iter++) << 8);
if (body_iter != body_end)
sum += static_cast<unsigned char>(*body_iter++);
}
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
header.checksum(static_cast<unsigned short>(~sum));
}
[EDIT]
What are the consequences if the checksum is not calculated correctly? Will the target host send echo reply if the echo request has invalid checksum?
If the checksum is incorrect, a typical IPv6 implementation will drop the packet. So, it is a serious issue.
If you insist on crafting the packet yourself, you'll have to do it
completely. This incldues finding the source IP address, to put it in
the pseudo-header before computing the checksum. Here is how I do it
in C, by calling connect() for my intended destination address
(even when I use UDP, so it should work for ICMP):
/* Get the source IP addresse chosen by the system (for verbose display, and
* for checksumming) */
if (connect(sd, destination->ai_addr, destination->ai_addrlen) < 0) {
fprintf(stderr, "Cannot connect the socket: %s\n", strerror(errno));
abort();
}
source = malloc(sizeof(struct addrinfo));
source->ai_addr = malloc(sizeof(struct sockaddr_storage));
source_len = sizeof(struct sockaddr_storage);
if (getsockname(sd, source->ai_addr, &source_len) < 0) {
fprintf(stderr, "Cannot getsockname: %s\n", strerror(errno));
abort();
}
then, later:
sockaddr6 = (struct sockaddr_in6 *) source->ai_addr;
op6.ip.ip6_src = sockaddr6->sin6_addr;
and:
op6.udp.check =
checksum6(op6.ip, op6.udp, (u_int8_t *) & message, messagesize);
I'm trying to experiment with using splice (man 2 splice) to copy data from a UDP socket directly to a file. Unfortunately the first call to splice() returns EINVAL.
The man page states:
EINVAL Target file system doesn't support splicing; target file is opened in
append mode; neither of the descriptors refers to a pipe; or offset
given for nonseekable device.
However, I believe none of those conditions apply. I'm using Fedora 15 (kernel 2.6.40-4) so I believe splice() is supported on all filesystems. The target file should be irrelevant in the first call to splice, but for completeness I'm opening it via open(path, O_CREAT | O_WRONLY | O_TRUNC, S_IRUSR | S_IWUSR). Both calls use a pipe and neither call uses an offset besides NULL.
Here's my sample code:
int sz = splice(sock_fd, 0, mPipeFds[1], 0, 8192, SPLICE_F_MORE);
if (-1 == sz)
{
int err = errno;
LOG4CXX_ERROR(spLogger, "splice from: " << strerror(err));
return 0;
}
sz = splice(mPipeFds[0], 0, file_fd, 0, sz, SPLICE_F_MORE);
if (-1 == sz)
{
int err = errno;
LOG4CXX_ERROR(spLogger, "splice to: " << strerror(err));
}
return 0;
sock_fd is initialized by the following psuedocode:
int sock_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
setsockopt(sock_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
fcntl(sock_fd, F_SETFL, flags | O_NONBLOCK);
bind(sock_fd, ...);
Possibly related is that this code snippet is running inside a libevent loop. libevent is using epoll() to determine if the UDP socket is hot.
Found my answer. tl;dr - UDP isn't supported on the inbound side.
After enough Googling I stumbled upon a forum discussion and some test code which prints out a table of in/out fd types and their support:
$ ./a.out
in\out pipe reg chr unix tcp udp
pipe yes yes yes yes yes yes
reg yes no no no no no
chr yes no no no no no
unix no no no no no no
tcp yes no no no no no
udp no no no no no no
Yeah, it is definitely not supported for reading from a UDP socket, even in the latest kernels. References to the kernel source follow.
splice invokes do_splice in the kernel, which calls do_splice_to, which calls the splice_read member in the file_operations structure for the file.
For sockets, that structure is defined as socket_file_ops in net/socket.c, which initializes the splice_read field to sock_splice_read.
That function, in turn, contains this line of code:
if (unlikely(!sock->ops->splice_read))
return -EINVAL;
The ops field of the socket is a struct proto_ops. For an IPv4 UDP socket, it is initialized to inet_dgram_ops in net/ipv4/af_inet.c. Finally, that structure does not explicitly initialize the splice_read field of struct proto_ops; i.e., it initializes it to zero.
So sock_splice_read returns -EINVAL, and that propagates up.