fpga4fun.com

Hi,
I have two separate problems involving FPGAs, but I have no experience whatsoever with them, so I thought it best to ask the experts.

My first is, I have an old (15 years) but very high-quality graphics tablet, but unfortunately the control circuit is 15 years old, and has a serial output. The system is running from an Xilinx XC3020A, fed by a 32-pin BIOS-like memory chip containing its instructions. My plan is to replace this old control board with a microcontroller-based solution instead which interfaces via USB, but is there any way to get useful information about the device through reverse-engineering of this FPGA and memory, or is this too complicated? The only other way of gaining knowledge of the tablet is through looking at the circuit diagram and a using a 'scope, and plenty of trial and error (manufacturer went bust ages ago, so no help there).

My second challenge is to take a 720P video signal from a HDMI cable, and re-scale and display the video on an LCD screen for which I have a full datasheet. From what I know, an FPGA is likely to be most feasible (or the only way? Perhaps a dsPIC could do this too? Anyone used both?), but I have no experience with FPGAs, and no development tools. How much do you suspect this would cost to do from nothing? Obviously I would need a reasonably powerful device to do video stretching at 30/60FPS and then convert that into monitor video signals. Is this a practical project for someone with little experience and a small budget, or is this beyond what I could realistically achieve?

Thanks in advance for any comments and suggestions,
Charlie

charliebruce wrote:Hi,
My first is, I have an old (15 years) but very high-quality graphics tablet, but unfortunately the control circuit is 15 years old, and has a serial output. The system is running from an Xilinx XC3020A, fed by a 32-pin BIOS-like memory chip containing its instructions. My plan is to replace this old control board with a microcontroller-based solution instead which interfaces via USB, but is there any way to get useful information about the device through reverse-engineering of this FPGA and memory, or is this too complicated? The only other way of gaining knowledge of the tablet is through looking at the circuit diagram and a using a 'scope, and plenty of trial and error (manufacturer went bust ages ago, so no help there).

What's are the benefits you are looking for with replacing the current interface logic? Higher sample rate? If the serial vs. USB is the only thing and you have the original drivers, I'd just build a serial-USB bridge and try to reverse engineer the serial protocol.

I don't have the drivers available unfortunately, and even if I didn they wouldn't be 64-bit or even WDM compliant (far too old), but taking the signal from the serial comms chip on the board is an option - and sounds like what I might have to do.

When I hooked up the tablet to a serial port monitor, I could see data being sent whenever a pen or mouse was present, but it would take me some time and guesswork to fully understand and parse the data being sent. I was hoping that if I could read the FPGA's code, it would make this somewhat easier, which is why I thought I might ask. The tablet also has what appears to be some internal settings, changable with certain regions of the board, but again I can't get a manual, so I don't know if these settings will change the board output (sample rate etc) and cause an issue. If disassembling the FPGA to find out more isn't an option, I'll have to work out this stuff out manually.

Can anyone offer suggestions on the HDMI -> LCD adaptor idea?