Interface to PC keyboard

Got a new project under consideration. Will want to use a standard USB PC-type keyboard. I will need to know how to interface this to a custom board we will make. Not sure which processor we will use yet. TBD.

Where can I find info on how to "talk" to a PC keyboard. In the old days, this was an 8048 and some "scan codes". I suspect that's not the case anymore with USB.

Frankly, I'd rather ditch the USB entirely, but I suspect that won't be viable if I want to use an "Under $10" keyboard off-the-shelf, and not try to roll something ourselves (either as keyboard, keypad, or something else.).

Since USB PC keyboards are commonplace now, I assume there is some standard way to communicate with them.

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This might help get you started:

Reply to
Michael Terrell

You should Google asbout Keyboard, it will tell a lot. In the old times the keyboard bus was two open collector lines, clock and data. Things were a bit complicated because sometimes it was the PC who send data to a keyboard. Arduino and many others have keyboard projects in the NET or at least available.

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mandag den 18. maj 2020 kl. 16.11.59 UTC+2 skrev mpm:

as far as I remember PS/2 is similar to I2C and I believe many keyboards still support it using the USB data lines, auto detecting which interface to use at power up

Reply to
Lasse Langwadt Christensen

We did some custom keyboards with Atmega chips before, but i don't have the code anymore. It's just emulating USB HID interfaces. There might be some examples in Microchip/Atmel site.

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They have firmware for HID -> SPI. I have not checked prices or availability. We have used a FDDI uart/usb before.

Reply to
Joe Chisolm

I don't think that is what he is looking for. Those chips connect a PC to control and SPI port. He probably wants a slave SPI port that connected to a USB master so his MCU has a simple interface to control the USB keyboard.

There are MCUs with USB host interfaces and I expect they will be the path of lease resistance. Either that or raid a PC graveyard. I hear Jeff may be obsoleting some of his inventory. The old PCs had very simple interfaces.

  Rick C. 

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Reply to
Ricketty C

HID (human uinterface device) is the subset of USB that covers keyboards, blinkenlights, pointers, and other physical controls. the standards seem to be availabe at no cost from USB-IF - they make their money from licensing.

Building a USB host is more complicated than building a USB device.

Reply to
Jasen Betts

Use same interface and scan codes; only thing different worth mentioning is the connector.

Reply to
Robert Baer

That FTDI chip could do the interfacing he needs. It has an internal microcontroller that can play USB host, allow a slave USB device to be connected, read data from it and talk to some other non-USB micro via UART or an other interface. There are pre-compiled ROM files for some common functions, including reading from a USB human interface device and sending the data over UART (over SPI is also available).

Reply to
Dimitrij Klingbeil

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