Author Topic: Connecting ps/2 keyboard to 3.3 volt fpga  (Read 2614 times)

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Offline rubenvannTopic starter

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  • Country: nl
Connecting ps/2 keyboard to 3.3 volt fpga
« on: August 02, 2016, 10:50:07 am »
I'm not sure if this is the appropriate subforum.

I have a 3.3V FPGA, and I want to connect a PS/2 port to the GPIO. However, the keyboard needs 5.0 volt and 0.50 mA.
I tried hooking it up to the GPIO directly, but the keyboard doesn't  do anything (it works when I use a PS/2 to USB adapter to connect it to a PC). I might have the pins configured incorrectly, but I don't think I have. (However, the pinout of the PS/2 thing doesn't allow me to hook it up to the VCC and GND pins on the GPIO, so instead I do ps2_vcc_pin <= '1'; ps2_gnd_pin <= '1'; in my VHDL code, which some sources say is fine but I still want to mention it)

As a test, I destroyed an old mobile phone charger which outputs 5.0V and tried attaching it to the ground and vcc pins on the ps/2. I figured that at least numlock should light up, but it didn't. I don't understand why, as this are, as far as I understand, the only pins that are inputs for the keyboard (or can the unconnected pins make some difference?).

What is the easiest way to use the keyboard with my FPGA? There are some answers online, but they mainly suggest using a voltage divider while I can't figure out where the vcc and gnd should come from. I assumed they should be just 5 volt if 3.3 is not enough, but this doesn't seem to work.

Apparently it's not, sorry. I'll open a new topic in the projects subforum.
« Last Edit: August 02, 2016, 04:30:46 pm by rubenvann »

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