Questions tagged [spi]

SPI is a low-level 3 or 4 wire serial bus interface with clock (SCLK), data in (MISO) and data out (MOSI). The fourth wire is a Slave Select to uniquely select a device on the bus. This signal is usually active-low. Slave Select, Chip Select, CS#, SS# stand for the same function, typically. Be sure to check the datasheet, though. The SPI bus is a *de facto* standard lacking the formal specification.

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MAX31865 data readout in continuous conversion mode

Reading the MAX31865 data sheet, it remains unclear to me when / how conversion results are latched in automatic (continuous) conversion mode. Figure 9 shows how /DRDY is set (it goes low when new ...
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Effect of Ethernet PHY interface on the speed of Ethernet

I have been working on this new project where I need to include Ethernet. But the microcontroller of my project doesn't have any Ethernet PHY included (no MII, RMII, GMII, etc.) So, I am instead using ...
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How to control write and read data beween SPI slave and wishbone master

I am trying to build a core that includes spi_slave wishbone_master. Now, I am able to read or write data between SPI and wishbone, but I don't know how to do both of them. The SPI is sending and ...
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SD Card Not Responding To Command 0 In SPI Mode

I am attempting to communicate with an SD card in SPI mode. I am running at 133kHz. I first send a hundred or so clock pulses over the course of a millisecond with the chip select signal high. I then ...
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How to use DMA to sample external ADC (16bit ADS8688) using SPI with both single ADC and daisy chain configurations

I am using an STMF446ZE MCU for a data acquisition + engine control unit application. My application uses four ADS8688's to sample 32 sensors. 28 of them are required to be logged at 100 Hz while the ...
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Interfacing LCD via SPI

Problem: I am trying to figure out how to interface an LCD via SPI. What is known: It is 80x32 dot matrix. There are 23 pins on a flex cable. The pinout. I'll put it below. The LCD is marked with red ...
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Configuring ICE40LP FPGA with STM32F4

I am new to STM32 programming and design, and my first project is to get an STM32F413 to program a Lattice ICE40LP FPGA (also a new platform...) via its slave SPI configuration interface (page 17). ...
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Should I continue use daisy chaining or use another Chip Select PIN in MAX7219 8×8 LED matrix module to increase height dimension?

Consider I have 4 daised chaining of MX7219 LED Matrix 8×8. Thats mean i have more width than height (32×8) or (width×height) If i want improve overal width of LED again, thats mean i must continue ...
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Is possible using SPI without SPI.h library with just using digitalWrite function?

I was trying understanding how SPI protocol works. Basically they are just bunch of 1's and 0's serially for every its pins. I wonder if I can send and receive data from SPI slave device without using ...
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MAX31865 and MAX31855 Completely not Working

I am beginner in Electronics. While working with MAX31865 and MAX31855 Modules it was working perfectly, but after designing custom PCB based on modules its not working. RTD shows -242C and 982C ...
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Is a high resistor value between GPIO pads acceptable?

I'm designing a PCB which involves integrating two microcontrollers - an ATSAMD51 (Cortex M4)-based Arduino, and a Raspberry Pi. I need to connect a parallel bus of 10 signals between the two devices. ...
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Daisy chaining NOR flash modules

for a project (FPGA image processing accelerator) I need to create a high bandwidth read-only memory. I settled on using Quad SPI NOR flash modules (will use them in XIP mode) but I have some concerns....
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Connect 3-wire SPI to ESP32

I have an "SPI" 4 channels with the below pinouts, datasheet is here: They say this is an SPI DAC, but from what I remember SPI is the following: CLK MOSI MISO CS However the above IC does ...
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Why are there extra bytes in SPI transmission for this STM32 microcontroller?

I transmit 3-byte(24-bit) using SPI from this Nucleo board with HAL as follows (SPIoutputBuffer is a char array): ...
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How to send a large amount of data via LoRa

I'm trying to implement a LoRa communication between two devices (master and slave). I studied two modules that seem to be interesting RFM96WE and SX1276. From the ...
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How to reduce the delay between GPIO pin state and SPI transmission?

Below shows SCLK, MOSI and CS(\SYNC) lines for my SPI from a logic analyzer: I use a Nucelo board as master to control this DAC(slave) via SPI. I didnt receive the DAC yet and trying to set the SPI. ...
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STM32H747 MDMA Transfer Error Address when using FreeRTOS

I'm using the MDMA to communicate with an external flash over QUADSPI. I have an implementation which works great without FreeRTOS, but when I implement it using FreeRTOS I get Transfer Error Address. ...
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How to know if an EEPROM IC can interface via Octospi?

I just learned that Octospi can NOT be configured to be used as a standard SPI device as Octospi was designed to be used to interface with external memory devices. The thing is, EEPROM ICs don't seem ...
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What is the clock idle state by looking at this SPI timing diagram?

The SPI clock polarity(CPOL) value is either zero or one and the actual value of the SPI clock in idle determines the value. For instance below SCLK is zero in idle and we can say that CPOL is zero: ...
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Control LEDs with 74HC595 shift register through SPI

I'm currently working on a project for which I need to control 16 white LEDs with two shift registers 74HC595 in cascade. I work on a ...
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A newbie question about SPI settings for an STM32 microcontroller board

I want to control this DAC's output via SPI protocol using an STM32 board. To initialize SPI3 in my case I use STM32CubeMX. And under SPI settings I couldn't relate the settings to the DAC's SPI ...
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Serial Interfaces - Why USB and PCIe require PHY while e.g. SPI does not require?

I'm trying to understand the reason why USB and PCIe (considering a single lane) can achieve higher data rates than e.g. SPI, I2C, UART. The reason may be the better handling of signal impairments at ...
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What is the maximum safe SPI baud rate for this DAC?

I'm trying to communicate with this DAC as quick as possible with a microcontroller board, and need to figure out what baud rate would be its maximum limit. There's 50MHz mentioned but I'm not sure. ...
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What is the best way to route a SPI Bus with multiple loads?

What is the best way to route a SPI bus with four loads? One bus with multiple drops. A star pattern with equal length branches to each peripheral. Or other configuration. All 4 peripherals and ...
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Weak edges over SPI data lines

I am developing a driver for an SPI temperature sensor, and having some trouble with poor quality edges near the end of packet on the data lines. While I am not experiencing any data loss, I am ...
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Is QSPI pseudo-sram here to stay? [closed]

Doing a new design for a industrial printer that was using an expensive SRAM part on an old Hitachi part. The new Cortex M processor has limited bus pins, and we're thinking of putting a QSPI RAM on ...
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Problem interfacing SD card module + CAN Bus MCP2515 module simultaneously on arduino UNO

I am trying to log data received on CAN bus to SD card using arduino UNO. each module works perfectly on its on, but when joining both modules together the CAN bus receives data normally but the SD ...
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Very confused with a DAC's SPI protocol

This DAC is controlled by SPI interface. And requires two bytes to write data to one of its registers. Below showing that the first byte is "register index" and the second byte is the data. ...
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Confusion with SCK MOSI timing relationship in SPI

I have a confusion correlating SCK and MOSI. Below is an example timing diagram of SCK and MOSI timing diagrams for an SPI: My first confusion is that: if the MOSI above is varying much faster than ...
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Why wouldn't an SPI SCK pin be a GPIO OUT pin too?

I have an ATtiny261 MCU. The pin diagram shows 2 digital out pins, PA1 and PB1. I've found a need for a 3rd output pin. From my (very) basic understanding of SPI, the clock is triggered on a rising or ...
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I2C high speed mode

I am working on a project which requires communication from a central controller and multiple peripheral sensors. Each sensor can push out data at a rate of 4-5KB/s(kilobytes/sec). There are 25-30 of ...
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ADS7822 wrong output values (SPI)

I am facing some issues with the output values from an ADS7822. The ADC is adequately bypassed and wired up, as follows. Please note that the inverted pins on the schematic are not an issue. I routed ...
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problem in echoing 8 bytes in STM32 SPI slave

Linux SPI master sends 8 bytes data of these every 1 second: ...
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STM32 discovery board resulting in wrong SPI MISO data

I recently purchased this STM32 Discovery Board in an attempt to start learning STM32 microcontrollers. Things have been going smoothly due to the CubeMX + HAL libraries. However, I'm absolutely ...
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Reading Lepton 3.5 VoSPI with ESP32

I try to read out a Flir Lepton 3.5 Thermal Imaging Sensor with my ESP32, but I got stuck and I don´t find a solution. Chapter 4.2.3.3.1 in the official datasheet gives some additional information ...
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Why is there a cutoff on these accelerometer measurement values? - ADXL375

I'm using a Teensy 3.2 to read data from an ADXL375 using SPI. In general the communication is going just fine and I can activate settings etc. However, when I try to read X, Y or Z data it seems like ...
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SPI broadcast: send / receive to many slaves

SPI Master is connected to the slaves with common MISO, MOSI, and CLK lines, with individualized lines for the selection signals. So, slaves share the MISO, MOSI, and CLK lines. I want to broadcast ...
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SPI transaction weird behavior

Im completely new to this topic so excuse any mistakes I make. I have a MMC5983MA sensor which works well with I2C. However Im having trouble with the SPI protocol. I have all wired up and im trying ...
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Changing SPI clock speed for DotStar LEDs connected to ESP32

I'm using an ESP32 with a strip of DotStar RGB LEDs that I'd like to control. I'm using the library's strand_test code example to verify my breadboard connections (I am using a level translator to ...
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Byte concatenation for SPI Transmit (STM32)

I want to transmit data to EEPROM via SPI but I can not concatenate command bytes and data bytes. In my scenario, I need to transmit 3 bytes of command and 64 bytes of data. How can I send this data ...
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How to understand the SPI clock modes?

There are many links on the web describing the SPI timing/clock modes. E.g., the following picture from here indicates 4 combinations of CPOL/CPHA determines when to sampling/transmitting data wrt ...
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ATtiny85 sharing SPI and I2C pins

I have an ATtiny85 sending messages via LoRa over SPI and I've hooked up a BME280 on I2C which I'm using with the TinyBME280 library. Everything is fine until I read the temperature, which then hangs ...
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What are the maximum recommended values ​for SPI/UART/USB series resistors?

Almost always in electronic designs resistors are used in series in the SPI/UART/USB connections to avoid overshoot, and they are encountered in values ​​between 10R and 350R. With what criterion ...
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Reading timing diagram correctly?

I have the following timing diagram of a SPI communication. Am I calculating total time T for receiving 24 bits correctly? Diagram:
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Can I use two SPI peripherals on the same STM32 MCU?

I want to use two SPI peripherals on the same STM32 MCU just to practice this protocol, because I don't have any other device to test with. Is it possible to do that?
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Connecting SPI with two different voltage reference

I have a project where I have a main board with a possible mezzanine board connected to it through a connector. The main board has a 12V supply and got a DC/DC for 3.3V voltage (call it 3.3VMAIN) to ...
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ESP-WROOM-02 SPI config not working as Slave

I tried to config the ESP-wroom-02, which have an ESP8266 core, as a SPI slave. But didn´t found much information about SPI configuration besides the technical reference ESP8266. The project have the ...
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SPI on SAMD21G18 not working

I've been attempting to use SERCOM2 SPI Master on the SAMD21G18J but have been unsuccessful. I tried the configurations with SERCOM0 and SERCOM4, and they both worked. The most intriguing behavior is ...
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Should HOLD pin be grounded in a macronix MX35LF1GE4AB chip if I only want to read data from it?

I have a Macronix MX35LF1GE4AB NAND Flash and I want to read its contents using an rarpberry pi. But I have trouble on how to wire the HOLD pin. Should I ground it. What I want it to read data from it....
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Best practice for a single digital (SPI) line routed to multiple devices

I am routing a SPI line to multiple follower devices. Currently I have a split in the trace like this: but it seems like this might not work well. Are there any best practices for routing to multiple ...
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