Society of Robots - Robot Forum

General Misc => Misc => Topic started by: krockhouse on January 16, 2010, 02:15:12 PM

Title: FPGA control using keyboard
Post by: krockhouse on January 16, 2010, 02:15:12 PM

I am making a robotic turret that can shoot an airsoft gun.  Our goal is to make it autonomous but for now I wanted to use a keyboard.  So I got a PS2 P-mod to attach to the FPGA and I have no knowledge of UART and am finding it pretty hard to understand.  Is there anyone who has used UART and could give me a short description of how I could use it to control my turret's servos?

Title: Re: FPGA control using keyboard
Post by: arixrobotics on January 17, 2010, 12:52:49 AM

Hi krockhouse,

I have used UART and controlled servos, but I have a few questions before I could help you any further;

1. Why do you need to use UART? Is it because thats the way to talk to the keyboard? (I've never interfaced to a keyboard before).

2. You need PWM, not UART to control servos. Unless if you are using a servo controller module that receives instructions through UART / serial. So are you going to connect the servos directly to your FPGA or use something in between?

I'm sure there are sites that explains UART / serial comm all over the internet. Google it up.

Title: Re: FPGA control using keyboard
Post by: krockhouse on January 17, 2010, 02:22:07 PM

The servos are controlled using the FPGA and I was going to code the FPGA to recieve the signals from the keyboard and change the servo timing which in turn moves the servos.  I wrote code that controls the servos by way of buttons and switches that are already on the FPGA board so the servo control aspect is down I just need to figure out how to recieve the signals from the keyboard and implement them in the control part, possibly through a counter of some sort that counts the keyhits of the arrowkeys and increases or decreases the angle of the servos.

Title: Re: FPGA control using keyboard
Post by: arixrobotics on January 20, 2010, 02:00:09 AM

Hi krockhouse,

So what you need now is the keyboard to FPGA interface ya? Hmm... I've never done this before, but upon googling around, I now understand why you need UART.

Unfortunately, I dont think I could help you any further. I have no idea on implementing UART on an FPGA. I suppose you will need to make your own UART code / bit-banging. But considering the fact that UART are very widely used, I'm sure there are pre-built modules for it, either by the FPGA developer or somewhere on the net.

If you ever think of using a PIC instead, then I should be of more help :)