This is my LabVIEW block diagram. My sensor is LIS2DH. I keep meet with error 5001: no 6 bytes read from the sensor. I use Arduino Uno r3. And I2C protocol to communicate. Why I can't access any data.
I want to use I2C to make Arduino Uno r3 and LIS2DH to communicate each other and output data as a graph.
Related
I am developing a measurement system, comprised of a MCU (being STM, ESP or PIC), multiple (let's say 8) ADCs sending data over SPI. ADCs are to be triggered using a SYNC signal so that they sample at the same time. It's crucial to access the data at the same time (or almost at the same time), the sampling frequency will be 1 or 2 kHz. I'm wondering how should I approach this: use a single physical SPI bus, and perhaps a DMA, or get a MCU with 8 physical SPI buses allowing them to operate in parallel?
Additionally, I would like this MCU to support Ethernet connection, to send the data to a post-processing unit.
My initial thought was to simply get a MCU with 8 SPIs, but maybe it's an overkill?
I am planning to develop a simple Profibus master (FDL level) in Linux, more specifically on a Raspberry Pi. I have an RS485 transceiver based on a MAX 481. The master must work on a bus where there are multiple masters.
According to the Profibus specification, you must count the number of '1' bits on the bus to determine when it is time to rotate the access token. Specifically after 11 '1' bits the next frame starts. 11 bits is also exactly one frame.
In Linux, how can I detect these 11 '1' bits? They won't be registered by the driver as there is no start bit. So I need a stream of bits, instead of decoded bytes.
What would be the best approach?
Unfortunately, making use of microcontroller/microprocessor UART is a BAD choice.
You can generate 11 bits setting START_BIT, STOP_BIT, and PARTITY_BIT (even) in your microcontroller UART peripheral. Maybe you will be lucky to receive whole bytes from a datagram without losses.
However, PROFIBUS DP datagram is up to 244 bytes and PROFIBUS DP requires NO IDLE bits between bytes during datagram transmission. You need a UART hardware or UART microcontroller peripheral with a FIFO or register that supports up to 244 bytes - Which is very uncommon, once this requirement is very specific from PROFIBUS.
Another aspect is related to the compatibility of baud rates. Usually, the whole range of PROFIBUS PD baud rates is not fully available on common microcontrollers UART.
My suggestions:
Implement this UART part on FPGA and interface with Raspberry Pi using e.g. SPI. You can decide on the extension of PROFIBUS stack portion you can 'outsource' to FPGA and the part you can keep on RPi.
Use an ASIC (maybe ASPC2, but outdated) and add another compatible processor to implement a deterministic portion of the stack. Later you can interface this processor with your RPi.
Implement using an industrial communication dedicated processor (Like TI Sitara am335x).
I'm relatively new to the I2C protocol and I have to write a c++ library for a particular sensor I have. I'm using a raspberry pi to interface and wiringpi (the i2c component) to handle the low level communications. This is a pretty standard library (read8bits, read16bits, readbuffer, same for write, that support register operations) so all I need to do is the specific, more higher level, sensor operations and export the sensor data to the main project.
But I have a problem, this particular sensor is a 10DOF IMU sensor
(https://www.waveshare.com/product/10-DOF-IMU-Sensor-C.htm) - which provides temperature pressure accelerometer magnetormeter and gyroscope information - and I've managed to get the pressure and temperature sensor reporting just fine but the MPU component is just odd...
So the sensor registers two I2C addresses, one for the pressure/temperature and one for the accelerometer/magnetometer/gyroscope.
Waveshare has a C library which I am using to understand how the sensor works and, for some reason the library is writing to different addresses (different from the registered ones). This particular sensor registers two addresses, 0x77 and 0x68, which I check with i2cdetect but consulting the code it has a particular address for the gyroscope and accelerometer and a separate one for the magnetometer (0xD0, 0x18 again) which should be the same.
So is it normal to do read/writes on addresses other than the registered ones? Would that even work? What am I missing?
The MPU-9255 is actually 2 separate I2C devices, the accelerometer and gyro are accessed on I2C address 0x68 (or 0x69 depending on the logic level of the AD0 pin), the the magnetometer is accessed on I2C address 0x0C.
The accelerometer and gyro I2C address are covered in section 7.2 of the MPU-9255 product specification. The magnetometer I2C address is in section 4.11.
The values that you are seeing in the code (0xD0 and 0x18) are shifted by 1, which leaves room for the I2C read/write bit.
0x68 << 1 = 0xD0
0x0C << 1 = 0x18
i need some help understanding a specific serial port connection from a sensor. I need to read data from the sensor and make some calculations in matlab or c++ (i will decide later)
The manufacturer only gives a chart with the following details:
Sensor Serial Port
Pin Number Mode Pin Description
I Trigger Input
I RS-232 Receive
O RS-232 Transmit
PWR Sensor Power (DTR)
PWR/GND Signal Ground
Not Used (Reserved)
Not Used (Reserved)
I/O RS-485 B Signal Pin
I/O RS-485 A Signal Pin**
So my question is: OK i know that pin 2 is used to receive data but how am i going to decode the volts stream into integers for example for my program? Also, i know that pin 4 gives power to the sensor. How do i know how many volts it has to give? Generally how am i going to learn all these details since the manufacturer does not give it?
Do you think Serial Port Analyzer Software will help?
Thanks very much in advance.
You might want to search for "DE-9 pinout YourSensorNameHere" in google or This page might be of some use to you. With most RS-232 you only need pins 2,3 and 5. With out more specifics about your sensor there isn't much SO can do for you.
I have successfully connected MATLAB with my Arduino. So far, I have only sent simple tasks to the Arduino such as digitalWrite and such.
The code I have been using is as follows:
%-- connect to the board
a = arduino('COM9')
%-- specify pin mode
a.pinMode(9,'output');
%-- write 0 (off) to pin 9
a.digitalWrite(9,0);
%-- dummy variable
on = false;
%-- simple loop to make LED flash 5 times
for m in 1:5
if on
a.digitalWrite(9,0); % turn LED off
on = false;
else
a.digitalWrite(9,1); % turn LED on
on = true;
end
%-- close session
delete(a)
Now that this basic test successfully passed, I wanted to get the SPI Arduino library to work with MATLAB. Is it possible to call a function from the Arduino SPI library in my MATLAB code? Specifically, I want to get SPI.begin(); and SPI.end(); to work from MATLAB, but a.SPI.begin() is not working. Is there some step I am missing?
To get the SPI library into an Arduino program, one must use #include <SPI.h>, but how can we make sure MATLAB knows all of the functions available in the SPI library? Hopefully it is not a problem that the Arduino SPI Library code is written in a different language than what MATLAB files are written in.
References:
MATLAB Support Package for Arduino (aka ArduinoIO Package)
Arduino SPI Library
The library "ArduinoIO" does not support SPI.
That library is just a serial port listener, and every matlab/arduino instruction send a code by serial, that is readed in the sketch on the arduino, translated in the corresponding arduino's instruction, and then executed.
You can create your own block that send some your-choise-spi-command, you'll also have to edit the arduino's sketch to execure the corrisponding SPI command. But you'll have to understand how the library works, change it's code, and so on.
It is way more faster (in execution speed, as serial comunication really is slow, and coding time) to code a "specialized" arduino sketch, that send back to Serial just the value you need, and then read serial and to pc-side computation.
To communicate with SPI device using Matlab support package you can use the following code:
a = arduino();
Spi_Device = spidev(a, 'D5'); % D5 is the pin number that you want to use for chip select
writeRead(Spi_Device,[hex2dec('00'), 100]); % 100 is the value that you want to send to the device
% When you done clear the spi object
clear Spi_Device
The Legacy MATLAB and Simulink Support for Arduino is no longer supported. I would recommend using the MATLAB Support Package for Arduino Hardware as that has built-in support for basic SPI communication.
There are getting started type of examples that comes with the support package and one of them shows how to use SPI.
Disclaimer: Even though I work for MathWorks, these posts are based on my experience with the software as a user. For actual Technical Support, please contact Mathworks' TS.