I have trouble getting UARTs working wi Simplest example of copying memory from one region to another using DMA ("Direct Memory Access") in userland. Jun 27, 2020 · The Pi is always the SPI bus master. I'm actually accessing the SPI0 via IOCTL calls but I have a very high dens Oct 16, 2012 · Hi Everyone, Thank you for all your enormous work! I have been trying to get the SPI to work but I am still getting the latency issues. If you are addressing an RP2040 SPI component, its data register has a specific location in the memory map, and a specific channel will either read or write to that address, with read_increment or write_increment, respectively, set to false, since the data register is at a fixed Aug 1, 2023 · Hello I am also struggling with a Pico configured as a SPI Slave. I'm actually accessing the SPI0 via IOCTL calls but I have a very high dens Jun 11, 2020 · Video signal captured at 2. Oct 24, 2021 · Join David as he explores Direct Memory Access (DMA) for the RP2040. Can some one give some example as how to set up SPI with DMA? I have the SPI set up to a FPGA where the FPGA is sending in data and the data needs through the SPI into the memory via DMA. h" #include "hardware/spi. Checking T0: hexdump_8(Expected:, 0x20002DC8, 1024) a7 f1 d9 2a 82 c8 d8 fe 43 4d 98 55 8c e2 b3 47 17 11 98 54 2f 11 2d 05 58 f5 6b d6 88 07 99 92 48 33 62 41 f3 0d 23 e5 5f 30 d1 c8 ed 61 0c 4b 02 35 39 81 84 b8 14 a2 9c b4 5a 67 2a ca e5 48 e9 c5 f1 b0 Sep 18, 2023 · A DMA channel is going move data from one location to another, so it needs to know where to read from and write to. c example code as a starter Mar 15, 2015 · I found the SPI DMA driver by msperl that supports DMA. Just type make <target> where target is either rpi1, rpi2, or rpi3, and then sudo . h" #include "pico/binary_info. This is intended to be unique but also SPI0, with two hardware chip selects, is available on the header of all Raspberry Pis; there is also an alternate mapping that is only available on Compute Modules. h Jun 15, 2024 · Hi, the following setup: GPIO5 generates an IRQ on falling edge (external signal at 1kHz rate) which starts an SPI DMA transfer of 128Bytes r/w with dma_start_channel_mask((1u << Jan 28, 2022 · 幸い、関数 HAL_SPI_Receive_DMA と HAL_SPI_TransmitReceive_DMA の受信バッファとそのサイズは送受信ごとに指定ができるので、たとえば最初に命令1バイトを受け取り、続く受信ではバッファを切り替えて大量のデータを受け取るという実装も可能です。 Jul 5, 2012 · The DMA engine is busy in the background writing out the SPI bits and reading in the 12 words of returned data. SPI is a simple protocol, you send x bits and for each bit sent one is returned. Mar 17, 2021 · The BCM2835 Arm Peripherals document only lists 2 SPI DMA Requests (DREQs), one for SPI0 transmit, and one for receive. com/roelvandepaarWith thanks & praise to God, and w Jul 29, 2022 · 1) spi_dma_handler is never triggered 2) dma_channel_is_busy begins responding with True and ultimately goes to false after ~512ms 3) the rx_buff progressively fills up just with 0x01 Sep 20, 2012 · So you have to create a kernel driver if you really want to use DMA - look at the spi driver for how the DMA regions are allocated and DMA is set up (SPI dma righ now only works if the spi_transfer structure contains non-null data for rx_dma and tx_dma. 27-v7l is installed. h Aug 28, 2017 · I'm looking into a issue on a Pi with SPI port, to clock continuously and stream data to memory area using a DMA. Although I have an array of 8 entries, and I have the transfer count set to 8 for the sending and receiving, it seems that DMA only does 3 transfers. I found this post where someone edited the config. In the hope of gaining additional data points, I changed the start address I received through the kernel infrastructure (0xFE201000) to the bus address specified in the peripheral manual (7E201000) for the DMA configuration, even though any information I can find on the topic says that is wrong. I wonder if it's possible in the DMA complete handler to enable an interrupt to detect when the SCK goes low, and then pull the CS pin high when it does so. DMA is used if the data length is larger than 96 bytes (BCM2835_SPI_DMA_MIN_LENGT). Have I hit a hardware bug on the pico, or is there an undocumented quirk of the UART I need to be aware of. Apr 28, 2021 · Raspberry Pi 400 Raspberry Pi Pico General SDK MicroPython Other RP2040 boards; Operating system distributions Raspberry Pi OS Raspberry Pi Desktop for PC and Mac Other Android Debian FreeBSD Gentoo Linux Kernel NetBSD openSUSE Plan 9 Puppy Arch Pidora / Fedora RISCOS Ubuntu; Ye Olde Pi Shoppe May 16, 2022 · High-speed transfer using SPI communication and DMA Mon May 16, 2022 1:37 am I want to build a mechanism to receive hundreds of data in 2ms by DMA and SPI transfer on RaspberryPi and I want to know if it is possible to receive data by DMA transfer using RaspberryPI4 or RaspiBerryPI3. Oct 27, 2023 · The DMA completes its job before the SPI block is finished transmitting data; it has no idea what the SPI block does with the DMA'd data, the DMA just knows when it's done doing its job. If the frames can be >17 bits, you could still use one of the SPI peripherals but only for SCLK, SDI and SDO, with software control of /CS to for framing. Apr 27, 2019 · Raspberry Pi 400 Raspberry Pi Pico General SDK MicroPython Other RP2040 boards; Software Raspberry Pi OS Raspberry Pi Connect Raspberry Pi Desktop for PC and Mac Other Android Debian FreeBSD Gentoo Linux Kernel NetBSD openSUSE Plan 9 Puppy Arch Pidora / Fedora RISCOS Ubuntu; Ye Olde Pi Shoppe Apr 23, 2020 · I've just pushed two commits to the rpi-4. c for an example of how to set it up. com Feb 1, 2022 · I feel like getting an Intel 8255 PPI clone and hooking it up to some of the GPIOs (8 data in/out and 5 or so control pins) would be a good way to go about adding an the most compatible LPT to a Jun 13, 2024 · After a while dma_channel_is_busy(dma_tx) returns busy and SPI DMA is dead forever. Feb 17, 2021 · Code: Select all SPI DMA example Actual frequency: 5681818 T0: Done. so here iam using DMA communication for spi transfer. Something in the separate configurations for the DMA to both peripherals is causing jitter to the audio going out to the DAC, which comes out as an audible 'crackling' distortion of the sound. SDK. Before sending pixel data, I do some Background & Software Setup. 04 with the kernel version: Linux ubuntu 5. The Raspberry Pi’s GPIO header exposes several SPI buses. Which are again references returned via dma_alloc_writecombine) The official documentation for Raspberry Pi computers and microcontrollers Hi, Can some one give some example as how to set up SPI with DMA? I have the SPI set up to a FPGA where the FPGA is sending in data and the data needs through the SPI into the mem Apr 11, 2016 · Bit bang SPI with DMA is highly specialised. I went ahead and added dma_mask as DMA_BITS_COMMON (basically 0xFFFFFFFF) to the bcm2708. Mar 31, 2022 · Raspberry Pi 400 Raspberry Pi Pico General SDK MicroPython Other RP2040 boards; Software Raspberry Pi OS Raspberry Pi Connect Raspberry Pi Desktop for PC and Mac Other Android Debian FreeBSD Gentoo Linux Kernel NetBSD openSUSE Plan 9 Puppy Arch Pidora / Fedora RISCOS Ubuntu; Ye Olde Pi Shoppe Jun 30, 2021 · Raspberry Pi Engineer & Forum Moderator Posts: 6088 Joined in which case you could change SPI0 to use a 40-bit DMA channel by adding "dtparam=spi_dma" to config. The mmc-spi driver determines if a device is dma-capable by looking at the dma_mask parameter of the spi master's device structure. Disabling the TX DMA while not sending is a workaround, but is tedious and not a clean way to do things. I have a time-sensitive task running with the DMA. #define DMA_DATA Nov 19, 2021 · This project makes use of DMA driven SPI to talk to SD cards. The getReading function works out where in memory the DMA engine has stored the words for the current reading and extracts the 12 bits for each attached ADC. 429609] bcm2708_spi bcm2708_spi. 83. use SPI mode 1) the clk is continued. Mar 25, 2023 · I handle SPI reads with DMA from userspace, as kernel based solutions (already implemented and my own driver) turned out to have too much latency sometimes - see this question the data format is: one byte "header" that indicates presence of data, and - if header is non-zero - 256 byte data chunk follows Jan 16, 2021 · I'm trying to establish communication between a Raspberry Pi and an STM32F407. SPI1 is available on models with a 40-pin header. 51-v7l+, but tried also to use Ubuntu Server with custom compiled kernel 5. CheckingT1: All good T0: Done. That allows circa 25 k samples per second for each ADC. It works good in polled mode, but i get unwanted fluctuations in the output signal. And some DMA controllers also do mem-to-mem xfers. c) from Martin's repository, re-compiled the kernel and installed the modules. On the Raspberry Pi 3 Model B, the BCM2835 core runs by default at 400MHz (resulting in 400/CDIV MHz SPI speed) if there is enough power provided to the Pi, and if the CPU temperature does not exceed thermal limits. /**V. y branch that fix some bugs in the 40-bit DMA support and allow the use of 40-bit DMA for SPI (17cba8a). . 2kHz). Thanks, Jack Mar 7, 2022 · I'm only able to use the SPI-DMA example as a reference to an extent as i need to somehow provide the I2C DMA instance from an address on the I2C bus to read from Jan 2, 2021 · Raspberry Pi: SPI DMA and continuous transfersHelpful? Please support me on Patreon: https://www. 1 when i check /sys/bus/spi/devices. I'm trying to use the DMA capable SPI master driver spi-bcm2708, following the instructions found at : Oct 16, 2012 · I'm trying to use msperl's SPI Controller driver to do a SPI transfer using DMA, but it fails with a timeout. however, currently there is a gap every 8bit clk with SPI mode 0(about 2 clk width), but when I switch the SPI SPH bit to 1 (i. Reordering them and also configuring a DMA channel for reading from the rxFifos (otherwise the PIO stalled) made the trick for outputting the right sequence. #include <stdio. Is this the best way to Feb 19, 2020 · We made fresh measurements on the SPI (we are using SPI1 to communicate with the FRAM). I can read at most 19k samples/sec with the spidev driver using ioctl's. I realise the CM4 uses different silicon, but maybe the same code is used for all Pi flavours, in which case it doesn't know how to set up DMA for the higher SPI channels. Missing some DMA interrupts with DMA-SPI? 21 posts • Page 1 of 1. PhilE Raspberry Pi Engineer & Forum Moderator Jun 16, 2021 · 1. 00:00 - Introduction00:44 - DMA Apr 6, 2022 · A minimum of 3 GPIO pins are required to connect from the Raspberry Pi to the MAX7219, specifically to the DIN, CS, and CLK pins. I also grappled with how to catch when the SPI is actually finished, and I'm not sure there's an easy answer. CheckingT0: All good T1: Done. 19. The Raspberry Pi has three types of serial interface on the GPIO header. txt to get the SPI's (somewhat) enabled. I don't think there is a benefit other than maybe more flexibility in selecting pins. 6 megasamples per second Adding an Analog-to-Digital Converter (ADC) to the Raspberry Pi isn't difficult, and there is ample support for reading a single voltage value, but what about getting a block of samples, in order to generate an oscilloscope-like trace, as shown above? Nov 29, 2022 · Code: Select all. 0: DMA channel 4 at address 0xc8808400 with irq 20 [ 6. On the other hand, the interrupt on the receiving DMA channel doesn't assert until all the data has been transmitted and received. pigpio uses the hardware SPI peripheral to generate the clock and transfer the data. Mar 1, 2023 · So effectively they have a tight polling loop within a IRQ, which seems a Bad Idea (TM). I would like to record more than 0. Designed by Raspberry Pi as both a development board, and as a reference design, the Raspberry Pi Pico series is a family of RP2040-based boards. Colour depth is 16 bit 565 format. Suppose I want to create a SPI master that sends data via DMA at, say Apr 28, 2015 · Some additional observations. the bandwidth (at 3Mhz) from a RPi (the master) isn't good enough to receive a 133 byte message so I started to look at DMA-ing the data in/out of the SPI peripheral - using the spi_dma. Based on Himax HM0360-MWA 640×480, Monochrome, up to VGA @ 60FPS max Designed for Always-on Service Applications Configurable 1-bit video data serial interface with video frame and line sync Ultra-low power consumption, standby < […] Mar 1, 2014 · immediately after a single character RX DMA, the TX DMA fires for one character. The Pi is running un Ubuntu 20. 4. h> #include "pico/stdlib. Jun 13, 2024 · Hi everyone, I'm searching for a simple code example to access SPI0 via DMA channels on a CM4(BCM2711). I indeed overlooked the order of the configurations and the calling of dma_channel_configure(). The SPI is configured with circular mode DMA. h> #include <stdlib. If a sample value is available, the A/D converter signals this by a DATAREADY output, which ideally can be intercepted by an input interrupt at the Raspberry PI Zero. I know how to use the receive FIFO interrupt now. Feb 6, 2022 · Raspberry Pi Pico. You need to read the datasheet for your device. The Pi is Master and the F407 is a full duplex slave. c and bcm2708. every time i need to write the fresh data to ram. DMA works well with PIO. One sends samples at audio rate to the DAC, (data_chan), and the other writes to the data_chan DMA control registers (ctrl_chan). Mar 27, 2015 · I am new to the Pi and am trying to read analog (audio) data through the MCP3008 device connected to a PI 2 via SPI. Which buses and pins are available depends on your Raspberry Pi model and configuration, as explained below. The sensor I connected on SPI on a Raspberry Pi 3, should be clocked with more than 3MHz, and has a wake up time on about ~200us, after first clock is send. Can anyone see what I'm doing wrong? I'm trying to control my WS2801 LED Stripe with my Raspberry Pi 4 over the SPI interface. 252432] bcm2708_spi bcm2708_spi. 10 Raspberry Pi 4B setup instructions. If you actually want to use DMA to construct the SPI waveform then have a look at rawWaveAddSPI . 905549] bcm2708 Nov 27, 2022 · Code: Select all. I'm actually accessing the SPI0 via IOCTL calls but I have a very high density continuous data flow to receive and put in a buffer, I want the minimise the RPI cpu usage. 6. was only using a few LEDs, not the 209 you seem to have. That means the Pi controls the SPI clock. However, the interrupt is generated when the FIFO is half-full(maybe), so I cannot always get the latest data. Jun 3, 2023 · I'm trying to run both the ADC and SPI at a rate of 96khz using separate DMA channels. However, the moment that transaction ends, the receive bu EVL patched Linux 5. SPI1, with three hardware chip selects, is available on all Raspberry Pi models except the original Raspberry Pi 1 Model A and Model B. The "M" in DMA is for "memory", so DMA controllers transfer between devices and to/from memory. txt. The usual approach is to use the Raspberry Pi pins that can drive the DIN, CS, and CLK pins. The actual data i'm sending from the Raspberry Pi to the DAC is an ECG(heart) signal via SPI. The problem with slave DMA is that you normally don't know the length of the transmission, but in your case it sounds like you'll be using fixed length messages. h" #include "hardware/dma. Hi, Can some one give some example as how to set up SPI with DMA? I have the SPI set up to a FPGA where the FPGA is sending in data and the data needs through the SPI into the mem Dec 4, 2012 · Device-to-device transfers are rarely performed, and simply not possible with typical hardware. Also provides 4x SPI with DMA configuration and sample application with reference board - DenizUgur/RPi4-EVL-4xSPI . andybiker, who introduced this technique. But my display accepts the 16 bit in 2 bytes in big endian format but the frame buffer /dev/fb0 is filled in little endian format. That has advantages. g. Page 158 10. Using RPi 4B, image 2020-08-20-raspios-buster-armhf-lite. The Pico family currently consists of Raspberry Pi Pico (far left), Pico H (left), Pico W (right), and Pico WH (far right). §SPI buses. img with kernel 5. /dma-example (must use sudo to get permissions for writing to DMA peripheral). NomiChirps Posts: 11 (DMA channel 0, DMA channel 1, and SPI) until Feb 12, 2021 · Only difference is I am directly pushing the data to SPI using DMA and not using PIO. 10. The SPI outputs to a dual channel 12 bit DAC for audio. 3 posts • Page 1 of 1 Sun Feb 06, 2022 9:03 pm . 3. – Jan 16, 2020 · I'm trying to enable all the SPI Ports on my raspberry pi 4 (as mentioned in the datasheet). Look at spi. This example is for a SPI master. The 12 32-bit words each contain 1 bit of information for each attached ADC. By default, the new GUID format is the concatenation of the four-character code (FourCC) (RPi4 0x34695052 for Raspberry Pi 4 or RPi5 0x35695052 for Raspberry Pi 5), the board revision (e. Jul 10, 2023 · Hello, I'm trying to use DMA to send and receive the bits from the SPI ADC that I'm using (ADC128S102). GPIO5 IRQ, SPI and DMA channels were prepared in main() according to pico-examples (hello_gpio_irq, spi_dma). 620387] spi_master spi0: will run message pump with realtime priority [ 6. The SPI and USART drivers probably already use DMA. Thus i need do get it working in DMA mode. instead of flushing l2 cache. Are you going to rewrite the SPI and USART drivers? Oct 25, 2021 · Maybe not. The wiki says it can't be used from userspace so I posted here in search of any workarounds or things like a tiny patch that'll sit between the awesome spi driver and general user applications. 0: SPI Controller at 0x20204000 (irq 80) [ 6. 0x00c03111 or 0x00d04170) (4-bytes), the least significant 4 bytes of the mac address and the 4-byte serial number. Introduction Arducam HM0360 is a low cost camera module built specifically for Raspberry Pi Pico and all available RP2040 dev boards. Sep 7, 2012 · Hi, I am trying to stream the frame buffer to LCD via SPI DMA. Enable SPI in the Raspberry PI. The spi_master_slave example seems to be polling the result rather than use the interrupt. c file (and now mmc_spi thinks the spi master is DMA capable) but now I get DMA timeouts in the manner that ldreeszaman See full list on github. Hunter Adams (vha3) Code based on examples from Raspberry Pi Co Sets up two DMA channels. There are only a 3 or 4 40-bit DMA channels on 2711, and enabling them on SPI claims 2 of them; for that reason I've made it an opt-in change - put dtparam=spi_dma4 in config. I'd like to read the chip faster (ideally 44. Which are again references returned via dma_alloc_writecombine) Sep 29, 2014 · The Python example I gave which uses pigpio makes the same underlying calls as the C library. These 3 pins are Oct 17, 2022 · when I using SPI with DMA , I expected that the clock of sclk should be a continue clk without any gap. So I don't want the DMA to be Dec 30, 2014 · Hi, Brand new on this forum and new on the Pi as well. 0-1030-raspi2 #32-Ubuntu SMP Su Additionally given a pointer to a structure representing a piece of hardware (e. 767241] bcm2708_spi bcm2708_spi. The official documentation for Raspberry Pi computers and microcontrollers Aug 14, 2018 · The documentation on the SPI peripheral says: Two DMA channels are required, one to read from and one to write to the SPI. Mar 7, 2024 · I am implementing pixel data transfer via SPI + DMA on Raspberry PI 3B+ I have an ili9341 display and I want to output 320x240x3 bytes of data over SPI with the help of DMA I have read carefully BCM2835 Arm Peripherals doc. patreon. 0: DMA channel 0 at address 0xc8808000 with irq 16 [ 6. May 4, 2022 · alastairpatrick Posts: 759 Joined: Fri Apr 22, 2022 1:39 am Location: USA Re: Writing data from SPI to FLASH via DMA. Aug 16, 2022 · Raspberry Pi Pico. Nov 21, 2022 · I am currently trying to set up DMA for an AD732x SPI 8ch Bipolar ADC, which needs 8 consecutive cycles of: - 1: Set SPI to MODE2, 16-bit Transfers Jan 28, 2024 · The DMA completion interrupt on the sending DMA channel asserts early; when the DMA transfer completes there might still be data in the transmit FIFO or transmit shift register. e. Mar 17, 2023 · If the frames must be exactly 17 bits, I think PIO is the only option (aside from bit-banging with an ARM core). Mar 31, 2022 · Raspberry Pi 400 Raspberry Pi Pico General SDK MicroPython Other RP2040 boards; Software Raspberry Pi OS Raspberry Pi Connect Raspberry Pi Desktop for PC and Mac Other Android Debian FreeBSD Gentoo Linux Kernel NetBSD openSUSE Plan 9 Puppy Arch Pidora / Fedora RISCOS Ubuntu; Ye Olde Pi Shoppe We used the Raspberry Pi 4B board to connect the LCD screen with the SPI0, and called Kernel SPI interface to send frame data in the LCD driver. SPI0 is available on all Raspberry Pi models. Mar 26, 2021 · This has been modified from the spi_dma project of pico-examples This much generates the SPI signal pictured above, but I don't understand how to get the slave pico to detect the transmitted signal. Install Raspberry Pi OS (32-bit) with the desktop on the SD card. 3 DMA seemingly explains what I need to, but this does not work. Jul 2, 2019 · I gave the sine wave as example, thus the data i need to send is between 0x3000 and 0x3FFF. I already enable the SPI interfaces over the raspi-config tool but that only gives me spi0. // // [*1] It might be possible to operate the SPI with a single DMA // channel. Oct 8, 2012 · [ 6. SPI does not know if a device is "ready to send". Included are examples of how DMA works with PIO and IRQ. so during transfer of DMA i need to transfer data to directly to ram. Any ideas, what could cause a crash of SPI DMA after a while? Thx i think the reason for that, is that you need to write a dma control structure to ram, and then poke some dma control registers to initiate the DMA and it would be a dumb idea to SPI master driver with DMA support for the Raspberry Pi - msperl/spi-bcm2835 Aug 19, 2023 · Bring up Raspberry PI. 0 and spi0. so here communication is spi. Oct 1, 2022 · Thank you so much for the answer. In order to write the SPI driver, we have to enable the SPI Dec 23, 2018 · I want to control a 24 Bit A/D converter via SPI with the Raspberry PI Zero w. May 25, 2020 · This physical address can be converted to a bus address, and given to the DMA controller, but you will find the end result is quite unreliable; there is a disconnect between the data that the user program is writing, and the values that the DMA controller is reading; the two don’t match up, unless you include very significant delays in the code. Oct 15, 2023 · All 5 DMA SPI channels working with DREQs to gate/monitor FIFO levels for (Linux box-quality) simultaneous sampling of 5 MCP3008s. So if you wanted to sample 8 channels you could have 8 ADCs and they would all be sampled simultaneously. Wed May 04, 2022 9:22 pm Jun 12, 2024 · Hi everyone, I'm searching for a simple code example to access SPI0 via DMA channels on a CM4(BCM2711). SPI handling will work just the same. The A/D converter is clocked with 27MHz, which results in a sampling rate of about 52kSamples/s. You're probably already familiar with the UART serial port, which allows you to open a login session from a serial terminal application, such as PuTTY. The other advantage of DMA SPI bit bang is the samples will be uniformly spaced in time. SPI2 is only available on the Compute and Compute 3. Pacing SPI DMA. I searched online and found bcm2835 library, but I couldn't find example as to how to set up SPI with DMA. Aug 23, 2017 · // The SPI side of the DMA channel must operate with 32-bit transfers // (see source/destination field in the DMA TI register). J'ai fais pas mal de recherche sur le net et je ne suis pas do Apr 26, 2013 · iam working on tft lcd interfacing to spi controller. Sep 20, 2012 · So you have to create a kernel driver if you really want to use DMA - look at the spi driver for how the DMA regions are allocated and DMA is set up (SPI dma righ now only works if the spi_transfer structure contains non-null data for rx_dma and tx_dma. Then install the kernel header using sudo apt install raspberrypi-kernel-headers; For your information, In our Raspberry PI 4 board, kernel 5. This is the bare metal forum. Rather than using the patch, I simply copied the two files (spi_bcm2708. Mar 8, 2016 · joan wrote:I believe the current Linux driver spi_bcm2853 can use DMA to fill the hardware FIFOs. dma_hw_t *dma_hw for the DMA controller), you can get an alias to the entire structure such that writing any member (register) within the structure is equivalent to an atomic operation via hw_set_alias(), hw_clear_alias() or hw_xor_alias() Mar 23, 2017 · Good morning, at newer versions of the the spi-bcm2835 driver there is the DMA mode included. Apr 23, 2020 · Bonjour, je cherche un moyen de communiquer avec un Raspberry PI 3 avec le bus SPI en mode esclave et transfert DMA. When setting up the spi speed to 35MHz, a the FRAM answers correctly, but for some reason the MISO data doesn't seem to be interpreted correctly by the CM4. A Raspberry Pi can control all 64 LEDs in a cost (pin-wise) efficient manner using only these three pins. 5s with continuous clock to the device. When the data is sent from the Pi, I do receive it at the F407. Is this necessarily true? I have a device where I need to write a few bytes by SPI and then receive a very large amount of data (eg 32k) back over SPI. not sync with the caches. Do you think using PIO will give any benefit considering the baud rate already at maximum. ra xp xu xx wi hd ea pf ds zm