Ok take look at code. But I have touched pcf IO expander. As you said, you have checked it with scanner and if you get address, line and device is OK. There is an example,snippet blocking mode, not irq based :. Generate reading condition and than read from PCF, data should be same as it was just written if nothing toggles IO expander.
Basically you can read byte or more bytes depends on device. In your case PCF 8bit gives only 1 byte. You can continue RW operations, or just simply wait till device automatically stop transition on line:.
This steps will write and read data. Anyway this chip has some tricky logic there, it more simplistic than it looks like. Extern input just triggers up PCF pin and nothing more, no special configuration for input mode.
If you want input pins, than just simply set pins to logic zero. So you should handle it. Here is some links: i2c explanations. Really nice guide! I found obvious mistake. Learn more. Asked 2 years, 4 months ago. Active 2 years, 4 months ago.Cookie Notice.
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If noone forces low level, the pull-up resistor on the bus will force high level NACK. In the addresses mentionned, you scan A0, A2, A4, A1, A3, A5 for read. All rights reserved STMicroelectronics.
Understanding the I2C Protocol
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STM32F103 SPL Tutorial 6 – I2C Interface
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Pick an awesome username. Your profile's URL: hackaday.Being occupied by all the courses and my research, I hardly had time to continue with the STM32F0 tutorial series I started almost two years ago. Hence, I thought that I need to spent some time to continue with this tutorial series to finish all the basic peripherals. If you are not familiar with I2C, I suggest that you take a look at the tutorial on Sparkfun website and come back here with these information in mind:.
I2C1 possible pin mapping. I2C2 possible pin mapping. Analog and Digital noise filter feature Analog and Digital noise filter: their benefits and drawbacks. In HAL library, there are several functions that provide us an easy solution to program I2C communication, particularly for Master mode. In this tutorial, I will only mention the normal communication without using interrupts and DMA. Hence, for master transmitting and receiving, we can classify the functions into 2 groups as following:.
HDC temperature and humidity sensor. You can take a look at the tutorial video below where I did pretty much all the explanation for this sensor and how to connect and read data from it through I2C connection.
Therefore, in this tutorial, I will be covering the following parts: Some basic ideas of the I2C and when we need to use it. Start condition can be issued multiple times repeat start in case a master wants to retrieve more data from slaves. Only the slave which has the same address sends the ACK back to the master. Some of the differences between these two modules are extracted from the datasheet of the F chip and presented in the table below. Based on the specifications of the targeted I2C sensor, the frequency is chosen accordingly.
The benefits and drawbacks of each filter are presented in Table 87 below. Analog and Digital noise filter feature Analog and Digital noise filter: their benefits and drawbacks 3. HDC temperature and humidity sensor You can take a look at the tutorial video below where I did pretty much all the explanation for this sensor and how to connect and read data from it through I2C connection.For a newbie adding an I2C device can be frustrating.
Several things need to line up properly for things to work. Various boards have different mappings between port number and GPIO number. Additionally, the stated ports in the program need to match the connected ports on the board.
That program is to discover the I2C address only. Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. I2C bus is a means of connecting several peripheral input and output devices that support I2C on two wires. The information is sent on these two lines using what is called the I2C communication protocol. I will not go into the details of I2C, but for clarity purpose you can get additional information here and here.
Additionally, you will also need a couple of I2C devices to test. I had a real-time clock module DS and a 0. In this setup, we will connect two I2C devices on the same bus. Additionally, it will also discover the I2C address of the two devices. In this setup, we will connect the two I2C devices on two separate buses. I used a NodeMCU board since that was handily available, you can use any other board. The image above is self evident. It is accessible to the program for read and write.
In this setup, we will connect the two I2C devices on two separate busses. If it finds one, then it publishes it on the Serial Monitor. An updated GITHub source code can be downloaded here. In any case you can downloaded the code here:. By jainrk Follow. More by the author:. Add Teacher Note.Программирование МК STM32. УРОК 33. HAL. USB. Virtual Com Port
What is I2C Bus? A set of hook up wires. I will present two setups for the purpose of demonstration. Setup 1: In this setup, we will connect two I2C devices on the same bus. Setup 2: In this setup, we will connect the two I2C devices on two separate buses. Did you make this project? Share it with us!
I Made It! Particle Sniffer by rabbitcreek in Arduino.Virtually all goods sold in retail have 1-D codes carrying electronics product identification codes EPC according to various standards or 2-D codes formatted in form of QR codes typically used for marketing purposes.
Barcode scanners all use a laser diode to illuminate the code, and a laser-diode detector, or a CMOS camera module to read the data.
These readers can be fixed at the point-of-sale or hand-held — either tethered or battery operated. Rich by its features-set, STM32CubeMX is changing its skin today to provide to the developers an improved access to the Pinout, Peripherals and Middlewares parameters to ease the configuration and optimized the project development time.
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It only takes a minute to sign up. More specifically, I am using the breakout board by Sparkfun. I am still a beginner when it comes to programming, and this is my first time trying to read data via I2C. I have made sure to progress slowly started by toggling LEDs, then writing to LCDs etc and now want to try my hand at sensing. However, I am really struggling with this. I have read the I2C protocol many times to try and get my head around it and I believe I am starting to.
I am using a standard 16x2 serial LDC to display information. For now, all I want to do is be able to read the data. I have looked on the mbed website for example codes to start out with and found none. I can't even find a library, although their quick start guide can't find a link, it just auto downloads a PDF claims there is one on the mbed site.
The problem is, these are both examples for using different equipment. I have attempted to convert it for use with mbed but obviously I have not been successful. I tried the same with the GitHub code, but was unsuccessful with that too. Going through both of these examples, I have attempted to decipher them and convert them for use in mbed and have come up with the following code:.
I have ran the Arduino code on the STM32 hardware and have managed to get the data displayed on a serial monitor. When I run my code, I get -1 read on all 3 axis.
It seems that I am deciphering the data incorrectly, or displaying it incorrectly. One of those 2 as the serial monitor is showing the wrong thing. This means it is all correct up untill here:. This bit doesn't seem to be doing what it should. Everything else is working as it should do, the correct registers are being read and written to, and the data is being sent back. I have confirmed this by comparing the signals against the Arduino code version that works. Working with the OP and building on the investigation explained in my answer to this related question " I2C Scanner not working properly ", the same two problems needed to be fixed first:.
As noted on another answer, a logic analyser would be helpful in this situation and should be used, if possible the following problems were found and fixed without using one, within the limited time available:. Earlier versions of the code were misled by a misprint in the SparkFun documents for their breakout board using this sensor, where they said the address was 0xC0. Also some code versions didn't left-shift that I2C address value, however the Mbed I2C functions want the address passed to them as an 8-bit version e.
At this point, comparing I2C bus activity on the scope between the Arduino code and the Mbed code, the OP could see that I2C bus activity was now identical, up to the point of triggering the measurement by the sensor. That left the final problem in the reading and display of the values from the sensor in the Mbed code. Looking in that part of the code, I removed the part which was reading from the sensor multiple times and checking for an incorrect return code.
Therefore I changed part of the original code from:. With this Mbed code, the sensor produces correct output, similar to the working Arduino code, and the point of the question was to get to that stage.
Again, further investigations of the I2C behaviour of the Mbed libraries and the sensor can be performed with a logic analyser, when an analyser and more time is available. You will immediately see if your address is correct or not, and how the device is responding or not.
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