MLAB wiki

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====== SPI Bus in the MLAB Kit ======

[[https://en.wikipedia.org/wiki/Serial_Peripheral_Interface|SPI]] is, alongside [[i2c|I²C]], another widely used interface. Its advantages include simple operation, high data transfer rates, and full-duplex bidirectional communication.

===== Interface Handling in Python =====

To use SPI from a Python program, there is an [[https://pypi.python.org/pypi/spidev|existing library]]. In Linux, it can be installed from the command line:

sudo apt-get install python-pip
  sudo pip install spidev

[[http://tightdev.net/SpiDev_Doc.pdf|Library documentation.]]

===== Options for Connecting Devices to SPI =====

==== Native SPI Interface ====

A significant portion of commercially available microcontrollers have an SPI interface as one of their peripherals.

==== Interfaces Created by Conversion ====

An SPI interface can also be created by converting from other standard buses.

=== From I²C ===

If the data transfer speed is not critical, the SPI interface can be created from the I²C bus using, for example, the [[i2cspi|I2CSPI01A]] module. This allows connecting multiple SPI slave devices.

=== From USB ===

When data transfer speed is important, it's preferable to use a bus with higher bandwidth, such as USB. To create an SPI interface, there are specific integrated circuits that mainly differ in software support:

* [[https://www.microchip.com/wwwproducts/en/MCP2210|MCP2210]] [[https://github.com/daniel-santos/mcp2210-linux|out-of-tree driver]]
  * [[https://www.ftdichip.com/Products/ICs/FT4222H.html|FT4222H]] - HID driver?
  * [[http://www.silabs.com/products/interface/usbtouart/Pages/usb-to-spi-bridge.aspx|CP2130]]
  * [[xvc_ft220x|FTDI FT220]] - a possible candidate when writing an HID driver

Connecting these chips to the operating system is rather [[https://christian.amsuess.com/idea-incubator/ftdi-kernel-support/|complicated]]. However, the [[best solution is probably|https://archive.fosdem.org/2018/schedule/event/rapid_spi_over_usb/attachments/audio/2461/export/events/attachments/rapid_spi_over_usb/audio/2461/USB_SPI_FOSDEM_2018.pdf]] using the MCP2210 on a new MLAB module.

===== Related Pages =====

* [[hbstep|Stepper Motor Driver]]
  * [[i2cspi|]]

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