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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How to calculate the maximum output rate of this DAC?

Regarding this DAC, if it is controlled by SPI how can we calculate the output speed? If I use max 50 MHz clock freq. for a single channel how fast the output would be? This must be something to do ...
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Multiple I2C devices and SD card [closed]

I am using Arduino which is interfaced with: 1 MAX17048 fuel gauge 1302 RTC (Software SPI) 4 INA219 current sensor Software Serial with ESP8266 SD card When I disable initialization of 2 of the ...
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Measure SPI signals by Siglent oscilloscope

I have a Siglent SDS 1102CML+ oscilloscope. I would like to inspect SPI signals: SCK (probe 1) and MOSI (probe 2). Why aren't these graphs rectangular like on logic analyzers? Do I need to configure ...
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How to change SPI mode externally? [closed]

My MCU only supports mode 0 and mode 3 in hardware. Yet my slave only supports mode 2. It works when bitbanging, but I'd like to benefit from the HW SPI for increased speed and lower overhead. As ...
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Resistors on SPI traces

I was looking at the schematic for the development board for the LTC2333-16 ADC, and I was wondering what the purpose of the eleven 33 ohm resistors (R10-R20) on the SPI traces was. There is no ...
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SPI bus termination for variable line length / variable number of slaves

There is a lot of information online for SPI bus termination, but my situation is a little bit different. I have created a system with the intention of 'plug and play' IMUs. Although the main ...
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ADC (AD7193) SPI communication with multiple devices

I am using an MCU (SAMD21G), to communicate over SPI with an SD card and an AD7193. I have both the SD and the AD7193 on the same SPI bus, each having its own CS pin. My concern is, when reading the ...
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External ADC with SPI NUCLEO-H743ZI2

I have an external ADC with a serial interface that has one data_out pin and CLK pin (16 MHz) the data_out pin transmit 16 bits of valid data then. An all-zero pattern follows the data after all valid ...
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nRF5340 incorrect SPI read

I'm trying to interface the MAX30001 ECG and bioimpedance sensor with nRF5340 using Zephyr OS. SPI write seems to work fine (not verified yet), but read definitively returns incorrect values. For ...
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ESP32-C3-DevKitM-1 SPI Master Arduino IDE

I've been using the ESP-IDE documentation to write an SPI driver inside the Arduino IDE for the ESP32-C3-DevKitM-1. I'm trying to use custom pins, and I have written the following code. Once compiled ...
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Control Neopixel with SPI on an ATmega32U4

I want to control one Neopixel using an ATmega32U4 (only one, so there is no problem with chain timing propagation). With the bit-banging library it does work great, but I want to use the SPI to free ...
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EEPROM usage in LAN9500 USB to Ethernet IC

I'm using a Microchip LAN 9500 USB 2.0 to Ethernet IC - Datasheet However, I don't want to use the EEPROM section, and I don't want the IC to be connected to any EEPROM. What do I have to do with the ...
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How can I write and read consistently in the W5500's registers using the EK-TM4C123GXL with SPI communication?

I used a modified code from an example for SPI communication "spiloopback" from Texas Instruments, where I tried to write data in the registers of W5500 and then read those data. ...
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Use one chip from multiple daisy-chained ADCs

My PCB consists of multiple ADC chips (AD7685) connected in a daisy-chain mode with STM32F303 as MCU and SPI communication. As far as I know, increase in the number of chips in the system results in ...
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How to read data from two shift registers in serial

I am dealing with an old circuit which has 2 shift registers in series and suppose to output 16 different values using SPI. The logic behind this circuit is a bit strange to me and I have a hard time ...
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Erratic SPI behavior between BeagleBone Black and ADS7883 ADC

Im trying to interface my Beaglebone Black with a TI ADS7883 SPI 12-bit ADC. My hardware implementation is the same as this tutorial, except with a slightly different pinout from the BBB, namely: <...
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Reference plane in small PCB

I have a small PCB, 6mm by 16mm with 6 layers. There are LVDS SPI signals (4 pairs) on this PCB, but due to the density and size of this board, it was difficult to have a reference plane under the SPI ...
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MCP2515 CAN Transceiver Breadboard vs direct PCB Female Header connection

I have experienced a case, where I connect the MCP2515 over jumper wires to uC and everything works as intended. However, when I plug MCP2515 directly in the PCB (through female headers), the MCP2515 ...
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MCP2515 CAN Enters Listen-Only mode couple of seconds after powerup on active network

I have experienced very weird situation, where the MCP2515 module enters listen-only mode (on its own) after couple of seconds (varies between 2 and 3 seconds). There is absolutely NO activity on SPI ...
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External SPI Flash Global Unprotect

I am using AT25DF041B SPI Serial Flash Memory with my application and I am confused about protection about sectors. When I have read the datasheet it says there is a command for the global unprotect. ...
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SST26VF064B flash communication problem with Quad SPI mode

I am trying to communicate with SST26VF064B flash and I was able to read the JEDEC correctly. I also tried to write and read a whole hex file and it worked fine. However, when I try to communicate ...
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Limit of daisy-chaining of multiple ADCs

I am designing a device consisting of 20 daisy-chained ADCs (https://www.analog.com/media/en/technical-documentation/data-sheets/ad7685.pdf) communicating via SPI with the STM32F303 microprocessor. I ...
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SPI bus maximum frequency with disabled devices

SPI Buses with multiple devices often contain slaves with differing maximum clock speeds. The speed of the bus is often set by the speed of the slowest device. In my application, I have a 100MHz shift ...
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Three-state buffer SPI termination requirements

I have question regarding SPI termination when using three-state buffers: Do we need termination resistor from master to three-state buffers (since ICs are very close) If we do, then do calculate the ...
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Logic Buffer for SPI level Shifter 74LVC126

I am using 5V logic microcontroller and I want connect the Hardware SPI bus to SD CARD and Ethernet chip(W5500). Using below circuit I am not able to initialization SD card. Below is my schematic: ...
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Help with MCP23S08

I’m not sure how to connect an MCP23S08 IO expander or write Arduino code for it. I would like the IO expanders to report button presses but I’m not sure where to start. It was recommended to create a ...
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SPI interfacing a sensor doesn't seem to work

I'm trying to get a feeling for how the SPI protocol works. I built this cirucit using Proteus simulator. simulate this circuit – Schematic created using CircuitLab And then according to the ...
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Current in a transmission line

I have a 6ft long SPI cable and I am trying to estimate the steady-state current demand on the driver. My transmission line is tuned to 100 Ω. That is, I've added a 50 Ω resistor in series with the ...
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Why does Flashrom only see the BIOS chip the when Arduino Uno signals are connected straight with 5V level?

I am trying to flash a BIOS (coreboot) with an Arduino Uno. The BIOS chip is an MX25L6405D (it is from a Thinkpad x200.) As I understand it from documentation, all signals must be 3.3V. If I connect ...
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Transmit error on CAN bus with MCP25625 boards

Setup: CAN bus with 2 nodes each with a microcontroller (CC26X2R1 LaunchXL evaluation board) and CAN controller with an integrated transceiver (MCP25625 click board). I used the libraries for the ...
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STM32F303 - is it possible to read the state of PB14 when in MISO SPI mode?

I have an ADC chip, CS5532, that sets the MISO line on PB14 Hi if data not available, and Lo if it is. Can I read the state of the MISO line? Every time I try to do it I read that the pin is Hi (I am ...
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Can I use any GPIO port for SPI interface in FPGA?

I want to establish an SPI communication between a Raspberry Pi and an Alchitry Cu. I found this code that implements an SPI slave interface, from the outside it looks like this ...
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Is it acceptable to gate an SPI clock (sck) to disable it when ss is high? (in an FPGA)

As far as I know, gating a clock in an FPGA is a very bad design practice because it can lead to clock skew and higher power consumption. This is specially true for the system's main clock, but what ...
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QSPI/QuadSPI: alternate bytes purpose?

I'm getting familiar with QSPI on my STM32F746-Discovery (not really relevant for the question, just some context). While reading reference manual, it lays out in details how the peripheral functions (...
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BME280 sensor locks ESP8266 and prevents booting

I have an AZDelivery Node MCU ESP8266 linked via SPI to a Adafruit BME280 Temperature, Humidity and Pressure Sensor that when the data connections are made it prevents the ESP from booting and ...
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STM32 SPI transfer only working correctly with first transfer, is there a relationship between the correct numbers and received values?

I have a custom PCB that contains a stm32f411re and a stm32f446re with the f411 acting as SPI master and the f446 is the slave. At the moment I have some very simple code, with the slave waiting in a ...
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How can I get higher fps with ESP32-CAM and ST7789 TFT LCD?

I have an ESP32-CAM AI Thinker board with an OV2640 image sensor and an ST7789 240x240 TFT LCD (SPI, but without a CS pin). I am trying to get a relatively good frame rate (30+ fps) on the TFT. I am ...
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PCap04 initialisation sequence

I'm developing SPI interface with so complex and badly documented PCap04 device. I've already implemented and tested all commands but always the results are very unstable. Even charge/discharge of ...
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SPI MISO line not working

I am using a KSZ8463 Ethernet Switch IC. When I connect the SPI MISO lane to another board having 2 peripherals - CPU and a CAN Controller IC - there's a spike of 0.3A current and the Switch IC stops ...
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Esp32 Dev Board fails to communicate with external power source

I'm using a 38pin wroom dev board. It works fine when it is powered by USB, however, if I cut VCC line from usb, and directly supply the board at the 5V (as it is supposed to have an internal vreg to ...
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SPI level translator

I'm planning to connect an IT8951 to an ESP32 through SPI. The issue is that the ESP32 module that I'm using has an output of 1.8V and the IT8951 works with 3.3V SPI. What kind of circuit should I use ...
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Detect how many push buttons are being pressed using a maximum of two Arduino pins

Imagine you have a varying number of push buttons that you need to connect to a microcontroller such as Arduino, of which you can only use a maximum of two pins (not counting 5v and gnd). Each button ...
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MCU to talk to 5 (or more) serials

I have a project where I need to talk to 5 devices over serial (RS232 to be precise). At 57k Baud. With a polling frequency that is as high as possible. The first step is probably to convert from ...
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LTC3300 active cell balancer - unreliable SPI communication?

I have been using the LTC3300 IC for a couple of years. I always observed unreliable SPI communication. I played with SPI timing and had the controller resend the commands until they get through... ...
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Help identifying an unknown SOIC-8 memory chip

I'm trying to dump the memory from a device for debugging. Based on what I know of the microcontroller (an ANYKA AK3918EN080) and the debug info returned from my failed attempts to dump the memory I ...
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Multiple RFID-RC522 readers on one SPI line

I have a project where it is necessary to drive multiple (4 to 8) RC522 RFID readers. The microcontroller (Raspberry PiCo) has two SPI buses, but there is no speed gain when using two lines instead of ...
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Combining 5V and 3.3V SPI

On a current project I need to interface several SPI slaves to an ATSAMS70 MCU. The MCU, and some slaves, are operating at 3.3V logic levels. Other slaves need to operate at 5V, so I need a level ...
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How to properly handle mixed RF/digital design in HFSS 3Dlayout

I have a big design imported from Altium into HFSS 3DLayout with several RFIC that I want to simulate. RF and Digital (SPI) nets are included in this design. I'm interested mainly in the RF side of ...
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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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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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