Uart dma stm32f7

I am working on project where i need to make laser beam stabilization unit. It does work, but have some problems. Only two things are nonfunctional, and this is where i need your help! This is what i am running. So this code looks very easy, after EXTI is called, and interrupt from FTH is generated, FTH will start to comunicate with memroy without any help of processor, and only thing i need to do is to wtite to correct memory part. So this is the code for HAL, but is half working, half not working, i was unable to reassemble any data from computer, even i did go into interrupt, and it try to send data into MISO pin.

Does any one can spot the problem and correct it? And here is what i am trying to do with STM32F7, but no luck, just go into void loop because it is missing something. I often have problems with getting interfaces to work and they rarely get fixed by looking at the code. So with your SPI I would connect a logic analyser on my scope but a free standing one will do to the bus. And I use the Keil development tools for software with Ulink2 type interface but the ST ones work fine.

Step 1. Idea is DMA will count spi clock pulses, and stores data based on my dma data jump, that is, communications just works, and no cpu is needed. With master mode SPI dues supply data stream, but for some reason, i can't get it inside computer. And bad thing as many users will say, only HAL libraries, and no one know how to use it.

Can't really help you much more right now - I have a plan to play with STM32F7 but too many other things on at the moment. It is written in very low level, and it is hard to translate to c code, as well as make right configuration in first time. You just have to put the time into working out how the chip works. It's a shame they've made the HAL much more complex than the old Standard Peripheral Library because it makes it harder to work out what it's doing.

It might be easier to sort out your problem in smaller chunks. Yeahi know If you can live with the 32k size limit of the free Keil toolset you could give it a try - I haven't caught them in a bad compile error for years.

There have been bugs in some of the library code. And how may market will they lose, only because they are not flexible? Does it takes huge amount of work and money, to create SPL libraries? For STM it should not be a problem. DMA just do shit, supply some corrupted data. It's hard to say what a hell is wrong, even if i am using direct sample how to use SPI with DMA, with no code modification.

So i guess no one? This is expected, sine ST reduced community to a handful of active members, good job Good way to kill this microprocessor line. This may be too late, but I succeeded with the attached procedure for the slave.So today I am writing this one here.

Starting with the simplest one i. The data is transmitted using blocking mode i. This method is good to use if you are only using UART and nothing else, otherwise all other operations will be affected. I am using toggle LED for you guys to better understand what happens when we try transmitting large data.

This is best explained in the video, Please check it out. At this point the data transmission is pretty quick and LED blinking rate is also constant. Now the complete data is being transmitted, but the LED blinking rate decreases. In interrupt mode, Transmission takes place in non-blocking mode or in the background.

You must watch the video if you want to see the working results.

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Check out the video at the end of the post. This will result in continuous transmission of data and the rate of blinking will also remain constant as the data transfer takes place in non-blocking mode. You will see that the complete data transmits after every 20 blinks. You can see this in the images below. You can also use toggle to continuously monitor this change. Check that out in the video below.

STM32 UART Rx using POLL INTERRUPT and DMA -- Keil -- CubeMx -- HAL

Your Name required. Your Email required. Your Message required. I will use all three methods to transmit serial data here i. To transmit data using POLL method, simply use You can see this in the images below You can also use toggle to continuously monitor this change.Cookie Notice.

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Your Privacy. Strictly Necessary Cookies. Performance Cookies. Functional Cookies. Targeting Cookies. Cookie Policy. Privacy Preference Centre. Moreover i understood that printf function is so complicated to be used.

uart dma stm32f7

I'm using an oscilloscope and LEDs to test my code and functions. Have a common ground lead. The IT variants on the other hand drop through, so you'll need to guard against calling them with data in-flight, but they would call the callback when the transfer is done. All rights reserved STMicroelectronics.

Cookie Notice Cookies and similar technologies enable us to provide you with an optimized user experience and functionality of our website. Accept Cookies. Cookie Settings. Privacy Preference Centre Active. Save Settings. Allow All. ST Community. Enter relevant keywords and click the Search button View This Post. July 9, at PM. I'm a beginner and i'd like to start with STM32, and use uart protocol to communicate between two FZI cards sorry for my english I saw lot examples on other stm32 without result when i code something.

GND pins are connected too. Login to answer this question.GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together.

If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. This example presents how to implement performance-efficient DMA timeout mechanism for peripheral DMA configured in circular mode. Implementing DMA for peripherals e. UART can significantly boost performance while reducing workload on the MCU microcontroller core [1]therefore configuring the DMA controller in circular mode can be straightforward for peripherals.

However, in time-critical systems or hard real-time systems it is crucial to perform the required actions within specified deadlines. A DMA controller is only able to issue interrupts when its buffer is either full or halfway full, however considering UART communication, in most cases the received amount of data is not known in advance and the end of transfer cannot be detected.

Consequently, when a transmission from a peripheral ends with a partially filled DMA buffer, and no further data is received over a certain period, a DMA timeout has to be implemented in order to process the remaining data.

A DMA timeout means that a detectable event e. The first method utilizes a timer in input capture mode. While this method is effective, it requires an available hardware timer and additional wiring.

The second method requires no hardware changes and additional peripherals, instead it uses the system timer and utilizes the UART receive interrupt. The drawback of this method is that the UART interrupt service routine is called often during transmission, especially when the configured timeout period is short.

This adds significant overhead to the system and affects performance and efficiency negatively. In this demonstration, a more efficient idea is presented to implement DMA timeout.

After generating an idle line interrupt, it is not generated again until there is new data received. For more information about how idle line detection and interrupt generation works, please refer to [3]. After detecting an idle line, a software timer is started with user-defined period. This method provides an efficient way to implement DMA timeout and minimizing overhead by generating a single additional interrupt UART idle line interrupt after the end of transmission.

The software source code and corresponding header files can be found in Src and Inc folders respectively. The DMA buffer size and timeout duration can be configured in main. When a UART idle interrupt occurs, the timer is set to the configured duration and decreased in the SysTick interrupt handler.

After timeout, the flag is set and the DMA transfer complete callback is executed. Then the data can be processed without being corrupted or overwritten by further incoming data.

uart dma stm32f7

In this demonstration the received data is simply forwarded back to the computer via USB. Skip to content. MIT License. Dismiss Join GitHub today GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together.

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Reference designs, schematics and board layouts to develop production hardware and Mbed-compatible development boards. All forums and questions are now archived. To start a new conversation or read the latest updates go to forums. We suggest you read this AN. To answer your questions: 1 The source, destination and transfer size are defined as parameters in the DMA start function:.

The benefit of using the DMA is to off-load the CPU of moving data, so using a small transfer size of bytes would be unusual.

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uart dma stm32f7

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I'm trying to figure out how to use this new HAL driver. Problem is that you have to specify the length of data to read before the interrupt triggers. I plan on sending console like commands of varying length so can't have a fixed length. I assume the only way to do this would be to read single characters at a time and build up a separate string.

I decided to go with DMA to get the receive working. I'm using a 1 byte circular buffer to handle data as it is typed on the transmitter's serial terminal. Here's my final code only the receive part, more info on transmit at the bottom.

So that's pretty much all the code to receive characters and build a string char array that shows what the user has entered. If the user hits backspace or del, the last character in the array is overwritten and if they hit enter, that array is sent to another function and processed as a command. To see how the command parsing and transmit code works, see my project Here. Receiving data while the Data Register DR is full will result in an overrun error.

Any new data will cause the overrun error. What I did was to rather use a circular DMA receive structure. It is a little bit more complicated because while the DMA does the circular buffering itself, you have to manually implement the loopback to the beginning if you go past the end of the buffer.

I have also found a glitch where the controller says it has transferred the data i. NDTR has decreased but the data is not yet in the buffer.

The only way they work out of the box is if you know the exact number of characters you are going to receive. If you want to receive an unspecified number of characters there are a couple of solutions that I have come across and tried:. Set the amount of characters to receive to 1 and build a separate string. This works but has problems when receiving data very fast, because every time the driver reads the rxBuffer it dissables the interrupt, so some characters can be lost.

Set the amount of characters to receive to the largest possible message size and implement a timeout, after which the whole message is read.

This is more work, but it is what I found works best in the end. You do have to change some of the hal drivers though, so the code is less portable. I had to face the same problem in my project.

It seems to work nice for me since I receive commands trough the USART whose first byte tells me how many bytes more the command is going to be long. Maybe it could work for you too! Usually i wrote my own UART circular buffer implementation. You can write your own circular buffer with just 2 array and pointers using UART interrupt flags.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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It only takes a minute to sign up. The code I use is mostly generated by CubeMX and is at the end of the post.

First of all I can't get the stm to transmit at baud rates higher then the standardaccording to the datasheets both the FTH and the STM32F7 should be capable of at least 12M baud. Also whats the right way to echo back all received data but make use of the fifo so no data is lost when it's not polled in time?

Maybe these are dumb questions but I already tried to find a solution on here and the rest of the internet but can't find any. There is no way to just append some more data to an ongoing DMA transfer. You can of course allocate a buffer yourself, add data as it comes, and restart DMA whenever it finishes and there is new data in the buffer. It looks like to me, that you can't have both DMA and interrupts on every received character.

At least, the ISR status register value would be useless, and the interrupt handler won't be able to decide what to do. Reading it could even interfere with the DMA transfer.

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Therefore, you must choose one. Using DMA to put the data in a buffer or twoyou can then poll the transfer counter regularly in the idle loop or a timer interrupt.

There won't be an immediate response, but it'd perhaps not matter at all, because the USB interface would incur some delay too. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered.

uart dma stm32f7

Asked 2 years, 10 months ago. Active 2 years, 9 months ago. Viewed 5k times. JaneDoe JaneDoe 43 1 1 silver badge 5 5 bronze badges. Active Oldest Votes. It's not in the code abovethen you'd get There is a difference of 4. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

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