Questions tagged [dma]

Direct memory access (DMA) is a feature of computerized systems that allows certain hardware subsystems to access main system memory independently of the central processing unit (CPU).

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38 views

How do CPU, IOMMU and DMA controller interact with each other?

While drawing an interaction diagram involving CPU, IOMMU and DMA controller, I failed to find any authentic document showing how they interact with each other. Is the DMA controller physically a ...
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24 views

Order of disabling in `HAL_TIM_IC_Stop_DMA` function -STM32 HAL library-

Here is the function body of HAL_TIM_IC_Stop_DMA: ...
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150 views

STM32 ADC over DMA Continuous Mode Too Greedy

I am trying to read ADC data via DMA on an STM32F412. The reading itself works fine but the rest of the program is not executed anymore so it's killed by the watchdog soon. I have an array of size 50 ...
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42 views

stm32f1xx how to use DMA to write to TIMx CCR

I am trying to control WS2812b digital LEDs with stm32f103. I have a buffer of color values for the LED strip and to transfer them I need to write the next value to the timer's CCR every time the ...
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1answer
47 views

STM DMA won't continuously transmit on UART line

I am using an STM32L4R5 board and am trying to configure the DMA on the UART2 line. I have managed to get the RX line to operate how I want, but when I follow "Transmission Using DMA" in section 44.5....
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22 views

Sending Out Incoming SPI Data Through UART- PICMX250128B

I am trying to send out data(via UART) I receive from a 24-bit external ADC chip(via SPI), the ADC notifies the PIC 32 when data is ready so I am using an external interrupt handler(EXT INT). The ADC (...
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1answer
139 views

stm32 which timer and DMA channel should I use?

I am trying to control two lines of digital LEDs (WS2812b) with my STM32F103 using Timers with DMA and PWM. LED strips data lines are connected to PB5 and ...
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2answers
120 views

How to invert PWM signal on STM32

I am trying to control a WS2812 LED with STM32F103. The LED is a digital RGB LED also known as Neopixel. They are controlled by sending 24 bits of color data per LED to the first LED's data pin. The ...
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1answer
54 views

STM32F103 ADC via DMA - sequence scan to RAM can't make it work as expected

I'm using an STM32F103C8T6 BluePill board and CubeMX generated init code (Low-level libs) to setup the ADC + DMA to sequentially scan though 8 channels and write to an array in RAM. However, it either ...
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1answer
66 views

STM32 UART: combining interrupt and DMA modes

I am trying to use UART3 of STM32F103K8 to rx data in interrupt mode and tx in DMA mode. Reception works well, but transmission ...
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1answer
50 views

STM32F407 Discovery Board DCMI to SPI Output [closed]

I am currently attempting to use a STM32F407 Discovery board to display images captured with a OV2640 CMOS detector on a ILI9341 2.2" TFT SPI LCD. My goal right now is to take a single snapshot and ...
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1answer
125 views

STM32F303 ADC+DMA Averaging of measurements

What is the best method of taking multiple measurements using ADC+DMA interrupts and averaging them? Currently I have an STM32F303 with ADC2 initialized with channels 3 and 18 (Vrefint). My aim is to ...
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51 views

Memory Boundaries in SRAM

I am trying to use the GPDMA which is present in LPC43XX parts. The UM10503 data sheet constantly warns about memory boundaries (datasheet section 21): basically it says that you don't want to try a ...
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1answer
41 views

M2P DMA transfer with trigger from a different peripheral

The microcontroller on my board is STM32F429IGT6 and I want to use a timer as a trigger of a DMA -e.g. HTIM_SOUND_SAMPLER- and transfer my data from an array to CCP of another timer -e.g. ...
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1answer
64 views

Multi-channels DMA Subsystem for PCI Express

Say i have a PCIe Gen2 x4 link running in a DMA subsystem. May I know when do we need multi-channels DMA configuration? For example, FPGA vendor like Xilinx offer up to 4-read & 4-write data ...
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1answer
228 views

Why is DMA Continuous Requests not selectable as enable for STM32F446RE?

I have an Nucleo STM32F446RE and I'm used to enable DMA Continuous Requests with ADC. But in this case, I can only select disable. Why? If it's not possible to use DMA Continuous Requests with ADC. ...
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54 views

AXI4-Stream TVALID stuck low between VDMA and video output block

I'm trying to buffer a single frame of video using a VDMA block on a Trenz TE0712 board (artix-7 based development board), based on a few examples (specifically Numato's framebuffer example and Xilinx'...
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1answer
132 views

STM32 - 2 MegaByte DMA Transfer ADC To SDRAM

I want to transfer 2 MB of converted ADC data into SDRAM. I'm using STM32F429 Discovery board which is shipped with a 4-bank SDRAM (1 Meg Bits x 16 Bits x 4 Banks (64-MBIT)). I've configured the ADC ...
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1answer
102 views

Atmel SAMD21 DMA Transfer Complete Interrupt not firing

I have configured the SAMD21 peripherals so that incoming audio data from I2S will be copied into a memory buffer with DMA. As the controller allows linked DMA descriptors, I have two descriptors ...
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1answer
126 views

Why does DMA send the first byte as soon as it is enabled?

I'm using DMA to send data to GPIOF which is configured as a parallel bus. DMA is being driven by update events on TIM8. TIM8 is configured in slave mode and starts on an output compare event from ...
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92 views

Interfacing DCMI with SDIO and FMC on STM32F446VE

I am attempting to implement a system which involves capturing 1080p images via a camera connected over 8 bit parallel DCMI and saving them to an SD card via SDIO. If I understand correctly I cannot ...
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155 views

STM32H7 - MDMA with DCMI

I am using DCMI peripheral on STM32H7 to capture an 320x240 monochrome image (1 byte per pixel) and DMA to transfer it to D1 SRAM. DMA uses FIFO, Threshold: Full, Data width: Word for both source and ...
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253 views

DMA, Interrupt and UART connection in STM32 for detecting chararcters

I am trying to make a project and am planning to use DMA for my UART from one STM32 to another STM32. Here are some details of what am I using: Chip: STM32F107RB debugger and programmer: Atollic for ...
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133 views

How does the DMA know “when to send” the next byte?

I'm transferring data from memory to a peripherial's register in an STM32 uC. For example take 20 bytes. I understand that after sending all the 20 bytes, the "Transfer Complete" interrupt will occur. ...
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1answer
26 views

MultiByte data integrity with DMA on STM32F3

Despite low-pass hardware filters on ADC inputs I am having a lot of erratic readings. There are 8 single-ended channels in DMA sequence and it is configured for cyclic sampling. Sampling time is set ...
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900 views

STM32H7 SPI DMA

On STM32H7 I'm using DMA for SPI transfer. I use SPI1 and SPI4, both in D2 domain, together ...
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5answers
550 views

Processing ADC conversion result: DMA vs Processor Registers

I have a periodic ADC conversion (every 50 micro-seconds) and I use the result to do some further calculations and update the PWM load registers. The ADC is triggered by the up-down counter of ...
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81 views

DMA and Instruction Pipeline

My university resources say that DMA transfers the bunch of data from IO unit to memory or vice verse when processor is not busy with data and address bus. According to the resources, DMA Controller ...
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2answers
2k views

How to configure DMA to receive variable length USART messages?

I am trying to receive USART messages on a microcontroller originating from PC which will command it to execute certain tests. I am using STM32F4, I chose to use DMA as messages on the same USART ...
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1answer
89 views

CS43L22 DMA constant beep noise

I am using CS43L22 with STM32F4 discovery board. I generate sounds by sending I2S messages to CS43L22 using circular DMA buffer (32 size array). However, chip creates a constant beep whether it's ...
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1answer
41 views

DMA Init code for ADC sampled data

I am trying to figure out how this DMA Initialization code is used to sample following 4 ADC channels and save data in 'adc_data'. ...
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340 views

STM32L4 ADC DMA only Triggers Once

for some reason my DMA only seems to update ADC values once. I've set it up so that the callback function simply raises a flag everytime the DMA converts the ADCs, this flag only seems to go off once. ...
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49 views

Custom PCIe DMA on Cyclone 10GX FPGA burst read stucks

I'm writing a custom DMA machine to read and write data to the host system from FPGA memory. I use the Altera PCIe IP core as end point device in Avalon-MM mode. BAR0 is set as 64bit bar, Avalon-MM ...
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222 views

STM32f7 ADC DMA transfer not populating the buffer

I'm trying to compute the FFT of a 100 kHz signal from the STM32f746G discovery board using the HAL and CMSIS DSP libraries and I've run into a few issues. My first issue was trying to trigger the ...
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81 views

Concurrent DMA streams handling UART

I've currently got a STM32F777VI microcontroller working with UART receive working through DMA. The problem starts when I try to receive data from 2 UART peripherals using DMA. According to the ...
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2answers
253 views

Garbage in SPI RX Buffer with DMA (STM32)

MCU: STM32f030f4p6 There is garbage in reception buffer, when I use SPI and 2 DMAs (for reception and transmission). ...
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1answer
123 views

STM32L432 full duplex DMA SPI slave locks up after communication starts

I am continuously sending a substantial amount of data between the STM32L432 and a FPGA using SPI in full-duplex mode. I decided to implement DMA on the L432 in order to increase the transfer rate ...
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2answers
317 views

Using Character Match functionality in a STM32F7 chip

I'm trying to implement a UART receiver that works by finding a '\0' in the datastream, OR when it receives 256 characters at which point the data should be processed by an interrupt. The point is to ...
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1answer
200 views

Why is DMA running continuously?

I'm facing a strange behaviour of DMA which I cannot explain myself. I just want DMA to send a data block (i.e. one 32bit word) to the SAI peripherie and quit then and give a "transfer complete ...
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834 views

STM32 HAL PWM output with DMA misbehavior

I use the Blue pill STM32F103C8T6 to generate variable duty cycle PWM with DMA and using HAL library. And stuck with undesired results. First, I generated code with STM32CubeMX v5.0.1, HAL v1.7.0, ...
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824 views

STM32 HAL UART receive timeout interrupt

I'm developing a software for the STM32l432KC (NUCLEO-L432KC) which uses 2 UARTS with DMA (RX DMA mode to DMA_CIRCULAR) using HAL. My problem seems to be quite common: the UART buffer length is ...
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165 views

STM32H7 DMA2D MEM2MEM rectangle coordinates

Question: how do I specify rectangle copy parameters of source (x1, x2, width, height) and destination (x2, y2) buffer using DMA2D registers, in memory to memory mode? My problem is that I cannot ...
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2answers
316 views

SPI using STM32's DMA sends one word too much

On an STM32F103 I configure SPI in 16bit wide mode and set up a DMA transfer to transmit one byte: ...
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1answer
74 views

Multi-tasking on an 8bit AVR -

I'm using an ATTINY816 (the new series AVRs) to manage a system that includes the following tasks: Simple audio "effect processing" (delay, pitch up, pitch down...) using internal ADC + DAC Storage ...
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1answer
681 views

STM32 cant get DMA on PWM

I wish to drive a set of NEOPIXELS (ws2812b) using the STM32F4 discovery board, so far i managed to get a 800 kHz PWM signal using the CubeMX. And And the following code: ...
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2answers
68 views

PIC32MZ, MPLAB Harmony with I2S hangs after adding extra function

I have referred http://microchipdeveloper.com/harmony:i2s-tutorial and am able to configure the I2S and read continuous data from a microphone. I am facing issue with the microphone data, and have ...
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3answers
2k views

STM32 ADC+DMA occurring only once

I'm trying to poll the value of the ADC and store it in a variable using DMA but the variable store the value of the ADC1->DR only once(when the program start). ...
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1answer
327 views

STM32f103 DMA with PWM repeating values

I have a Blue Pill (STM32F103) and connected to it a ws2812b led strip. I am trying to send data to the led strip via PWM over the TIM2 peripheral (Pin A0). To change the duty cycle of the TIM2 PWM I ...
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1answer
846 views

What do these arrows on a pinout represent?

What do these arrows represent? Is there any way to memorize it easily?
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1answer
218 views

Does not trigger an interrupt DMA when reading SPI. Last byte transaction not coming

I use DMA for reading with SPI flash using USART. MCU - master, flash - slave. I read 1029 bytes per transaction. Exchange algorithm: I activate the flash (CS = 0) I configure the DMA channel to ...