Need advice on the following implementation

[pavjayt]

Not sure how to write the subject line for the following question. Basically the project is to derive certain signals/waveforms from a given master signal. Currently this is all hardware based and would like to move it to a user programmable interface and probably using a microcontroller (maybe a basic FPGA). This is totally new to me and hence need some good advice based upon your experiences.

Input - is a master clock anywhere between 15Khz - 16Khz, this is a pretty stable signal and is available either in sine wave form or TTL form
Output 1 - a pulse train based on input (this can be a fixed width, doesnt need to be programmable)
2 - a pulse for every X number of input clocks (again this can be a fixed width, but needs to be user programmable for X, where X is usally >512)
3 - a ramp signal with the frequency of output 2 (needs to be user programmable for offset & amplitude & low to high or high to low option)

Need a programmable delay for input signal. Then the input should be fed into a PLL that can be used down the stream for generating outputs 1-3. User should be able to control the above from a PC (any kind of interface works).

Any ideas/suggestions?

thanks in advance

 

[MikeMl]

Schmitt trig gate/inverter to square up the input clock?
12 or more bit binary presetable up-counter driving a DtoA?
Set the amplitude and direction (inversion) of the ramp using an opamp(s)?

 

[pavjayt]

Schmitt trig gate/inverter to square up the input clock?
12 or more bit binary presetable up-counter driving a DtoA?
Set the amplitude and direction (inversion) of the ramp using an opamp(s)?

Thanks for your suggestions, but I already have everything done by pure hardware (74HC ICs, 556 timers, 12bit counters etc). I want to do the same using an FPGA to program and control the above and have a PC interface. Not sure where to start for this other than reading books on FPGA.

 

[alec_t]

Seems straightforward for a micro. They're good at counting, detecting user input from keypads etc, and outputting a PWM signal which can be smoothed to give a ramp with offset and programmable amplitude. An opamp can then give polarity selection.

 

[MikeMl]

FPGAs dont do D/A, nor the analog parts, so the best you can do is to build a presetable counter inside the FPGA

 

[alec_t]

FPGAs dont do D/A

You could, however, use weighting resistors on a set of FPGA outputs to get a simple D/A.

 

[MikeMl]

Simple D/As consisting of resistors connected to digital I/O pins are good for maybe 4 to 6bits; OP needs 12.

 

[pavjayt]

I am sure there are ways to do this, but I am looking to keep it simple rather than using full featured FPGAs like one of the Xilinx FPGAs (ex: Virtex-5/ML-506) and this would be a good learning project for myself. For what I want to do, that board is an overkill, but it does have an onboard DAC and ADC.

https://www.xilinx.com/products/boards-and-kits/HW-V5-ML506-UNI-G.htm