Stm32h7 uart dma example

agree with told all above..

Stm32h7 uart dma example

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If you are using DMA then you will have two interrupts: one when half of the buffer is transmitted and another one when the second half is transmitted whole. Both of them should be fired if everything is OK. The reason behind this is that when sending a huge amount of data, you can start loading new data into the first half of the buffer in the TxHalfCpltCallback while the second half of the buffer is being transmitted by the DMA. And again you can load the new data into the second half of the buffer in the TxCpltCallback while the first half is being transmitted.

The advantage is that you do not have to wait for the whole transmit to complete before copying the next chunk of data into the buffer, but you can already start loading it while the transmit is still in progress.

The first half of the transmit buffer is loaded with new data by the CPU in the Transmit Half Complete interrupt callback, while the second half of the buffer is being transmitted by the DMA in the background. Then, in the Transmit Complete the second half of the transmit buffer is loaded by the new data by the CPU while the first half previously updated is being transmitted by the DMA in the background.

It is much easier to code DMA transfer and receive of course when you use the bare register approach, instead of the juggernaut HAL monster. For me, I was getting an transmit error when using DMA. The issue was solved by enabling the TXE interrupt:. Learn more. Asked 3 years ago. Active 5 months ago. Viewed 34k times. I would like to ask someone to give us an example of configuring UART in a project. Nixmd Nixmd 3 3 gold badges 7 7 silver badges 15 15 bronze badges.

Active Oldest Votes. Bence Kaulics Bence Kaulics 3, 7 7 gold badges 23 23 silver badges 47 47 bronze badges.

I assume that isn't necessarily when the data from the buffer is actually put "on the wire"? I have my board hooked up to a logic analyzer and get a trace similar to that shown in visualgdb. Alex Well yes, also there is some measurement error added by the GPIO toggling and the sent data is not that much as well. With thousands bytes it would be more centered I think.

But yes it is not that accurate. Eric MSFT 2, 1 1 gold badge 14 14 silver badges 28 28 bronze badges. Jonas Kibildis Jonas Kibildis 51 1 1 silver badge 3 3 bronze badges.

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UART Circular buffer using DMA and IDLE line detection

Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Socializing with co-workers while social distancing. Podcast Programming tutorials can be a real drag. Featured on Meta. Community and Moderator guidelines for escalating issues via new response….Nuggets of info about the STM32H7 as it applies to building a network analyzer.

DMA on the STM32H7 is a beast, with each incremental improvement as their hardware got better represented by a different interface. There are a few limitations. The most useful information came from:. The FIFO appears to get starved if the timer fires too fast. It should be noted There was more speed to be had. In the 3 DMA stream case of You can get a few percent more clockcycles through overclocking.

It's very important to use an external crystal that can be desoldered for testing it. By pointing 3 DMA streams at different domanes, the speed increases to 22Mhz. Things were looking good when benchmarking with 1 writer stream, but with the 2 other streams reading, the reader FIFOs once again would stall until the speed was reduced to 12Mhz.

More importantly, there were significant timing errors when reading from the GPIO, causing bit errors anywhere above 1Mhz. There doesn't seem to be any way to force when multiple DMA streams read a GPIO, so it's worthless for reading all but the slowest parallel data. There are no examples of this actually being done.

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In the case of writing 16 GPIO pins from a buffer, you can do:. That fires bytes at the GPIO, bytes at a time. The datasheet has a note about ping ponging 2 FIFOs, but there's no evidence of how to enable this.

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It's acceptable for just transferring data, but not for driving a DAC. Managed to recover it by desoldering the crystal, only because it didn't use the internal oscillator by default. The network analyzer proved very noisy. Part of the problem was noisy analog reference voltages.

A capacitive multiplier might have fixed that. On a board measuring microvolt analog signals like this one, the radiation at even 10Mhz would be a problem. Yes, delete it Cancel. About Us Contact Hackaday. By using our website and services, you expressly agree to the placement of our performance, functionality, and advertising cookies. Learn More. Impedance matching The network analyzer proved very noisy. Ok, I agree.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.

STM32 tutorial: Efficiently receive UART data using DMA

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.

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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.

The master ought to be similar.This repository may give you information about how to read data on UART by using DMA when number of bytes to receive is not known in advance. For each mode, it requires number of elements to transfer before events are triggered. Imagine application assumes it will receive 20 bytes, but it receives only 14 :. If even this is not available, then application may use only polling modes with DMAwith examples provided below.

Practicle example: Imagine we received 10 bytes at bauds. Each byte at bauds takes about 10us on UART line, total us. IDLE line interrupt will notify application when it will detect for 1 character inactivity on RX line, meaning after 10us after last character.

Application may react on this event and process data accordingly. If we move to previous example of expecting to receive 20 bytes by application and actually receiving only 14we can now:. For cases Pbelow snippet shows how to get DMA positions and how much data to process. DMA hardware takes care of transferring received data to memory but application must constantly poll for new changes and read received data fast enough to not get overwritten. Processing of received data is in thread mode.

Idea is completely the same as in previous case polling only but it uses separate thread for data processing.

Similar to polling except in this case user gets notification from 3 different sources:. Tags: asynchronous direct memory access dma idle line stm32 stm32 family stm32f4 stm32f7 tutorial usart usart idle. Owner of this site. Application engineer, currently employed by STMicroelectronics. Exploring latest technologies and owner of different libraries posted on Github. View Results. Latest updates and examples are available at my official Github repository.Most of us know the importance of ADC and the fact that simpler it is to use the ADC in any device, the more easier it is to make any project.

Most of the sensors use ADC for data transmission to the microcontroller and that's why ADC plays an important role in any embedded system design.

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Earlier microcontrollers, such asdidn't had ADC built in to the microcontroller and so there were external ADC connectors, making design more complex. But we will start from basics and take one step at a time. DMA request generation during regular channel conversion.

If enabled, ADC will Continuously sample and convert. Scan Conversion mode. Configures the sequencer of groups. If it is disabled, conversion is performed in a single conversion mode the one defined in rank 1. If enabled, conversions are performed in sequence mode up the rank. Discontinuous Conversion mode. Discontinuous mode is used only if sequencer is enabled parameter 'ScanConvMode'.

If sequencer is disabled, this parameter is discarded. HOW TO:. Leave the clock untouched and go to the configure tab and select ADC. Now make sure your configuration is as in the picture below. Scan conversion mode is disabled because only one channel is selected and sequence is not needed at this time.

Continuous conversion mode is enabled as we want adc to work continuously. As mentioned above, we will take one step at a time, starting with the most basic one. Also I will be using HAL libraries to write the code. So let's start with PollForConversion method.

This will Poll the ADC and wait for the conversion to end. We can specify timeout in case of errors. Timeout is the timeout in case of errors. With something in front of it, the second LED glows and the value in the debugger decreases. To avoid this, we will use interrupt in the upcoming tutorial. To Download full code, visit.Cookie Notice. Cookies and similar technologies enable us to provide you with an optimized user experience and functionality of our website.

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Can this be done using CubeMX? When debugging Rx buffer is set to something other than zero once everything has been initialized as seen below. All rights reserved STMicroelectronics.


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Application uses use default features to implement very efficient transmit system using DMA. While it is straight-forward for RX, this is not the case for receive operation.

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When implementing DMA receive, application would need to understand number of received bytes to process by DMA before finishing transfer.

This is especially true when UART is used for system communication where it has to react in short time after all bytes have been received.

This is achieved using one of 2 available methods:. Both events can trigger an interrupt which is an essential feature to allow effective receive operation. When not available, examples concerning these features may not be used.

IDLE line event triggers an interrupt for application when line has been in idle state for 1 frame time in this case us after third byte has been received. After IDLE event is triggered, data are echoed back loopback mode :. For each mode, DMA requires number of elements to transfer before its events half-transfer complete, transfer complete are triggered. As for the sake of this example, we use memory buffer array of 20 bytes.

Listed are steps to begin. This configuration is important as we do not know length in advance. Application needs to assume it may be endless number of bytes received, therefore DMA must be operational endlessly. We have used 20 bytes long array for demonstration purposes.

In real app this size may need to be increased. It all depends on UART baudrate higher speed, more data may be received in fixed window and how fast application can process the received data either using interrupt notification, RTOS, or polling mode. Everything gets simplier when application transmits data, length of data is known in advance and memory to transmit is ready. For the sake of this example, we use memory for Helloworld message.

In C language it would be:. There are 2 sets of examples:. Processing of incoming data is from 2 interrupt vectors, hence it is important that they do not preempt each-other. Set both to the same preemption priority!


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