Fpga to probe connection board to realize an open source oscilloscope - Page 1
Forum section: electronics / projects

author: ch.onillon
author_rank: Newbie
timestamp: February 21, 2015, 05:55:00 pm
content: Hi,As we can see on the dave's video, many people work on the reverse engineering of oscilloscopes (like rigol).So, i'm looking for the possibility to realize an extension board for the existing fpga boards like papillio duo/murato/knjn boards to add high speed acquisition.I think that could be great to combinate for example a raspberry pi 2/ 8" inch screen/ touch screen / fpga board for an accademic purpose / fft /spectral analyser for example.And why not using a 3d printer to realize the front panel and use a microchip usb device/ Arduino to realize a front panel with dedicated button.According to the existing fpga analyzer from dangerous prototype, it could permit to realize a nice mixed signal oscilloscope.the constraint will be the analog part of this open oscilloscope.it's true that exist Tools like pi scope, but i would really have to have something like the rigol.People will say "don't reinvent" but the goal is to start and after to see where it go (why not to create Spectrum analyser / Frequency generator) , etc ....analog experts, your advice ?- schematics- a/d reference design ...already thanks for you help.Br,Christophe

author: nuno
author_rank: Frequent Contributor
timestamp: February 21, 2015, 06:25:32 pm
content: One relevant recent thread, there are others:https://www.eevblog.com/forum/projects/diy-oscilloscope-front-end-queries/

author: ch.onillon
author_rank: Newbie
timestamp: February 21, 2015, 08:48:29 pm
content: Hi Nuno,Thank you for this quick response. yes, it sounds like what i'm looking for.It can be very interresting at this point to concentrate to the analog part and work with a logi pi card for example, it could be a nice wing (shield)I begin to understand better how it work (based on bitscope).Capacities and resistance for entry.Amplified OP to scale/positionate data.According to what we see, it can be possible to concentrate only the analog part and use the logi pi card for example to do the job.It sound really good.honestly, a complete open source solution could be very nice, isn't it ?i'll start on the fpga part and see how to use existing informations.

author: tggzzz
author_rank: Super Contributor
timestamp: February 21, 2015, 08:53:54 pm
content: If you want reliable operation with fast edge transitions and wide busses, you will need good signal integrity between the wing and the FPGA.There are two pre-requisites for good signal integrity: controlled impedance connectors and ground connections neareachsignal.Unfortunately one of the major differences between the professional FPGA boards and amateur FPGA boards is that the amateur boards don't have enough ground connections, or they are all grouped "conveniently" together at one end of a connector.

author: ch.onillon
author_rank: Newbie
timestamp: February 21, 2015, 09:05:30 pm
content: Thanks tggzzz,Your remarks are interesting (sorry for my English, speak better than write it).i would add an ADC on the wing shield to be able to work in high frequency, The goal of the fpga will be to transmit digital information to ram.So the wing will do all the job and the fpga will just obtain a converted value on a 8 bit dedicated bus.After i agree with you that it ll limit the speed acquistion to :convert the analog value by the ADCinform the fpga convertedfpga read the value on the adctransmit to the RAMAllow the adc to obtain new conversion.

author: ch.onillon
author_rank: Newbie
timestamp: February 23, 2015, 12:37:00 pm
content: I think that's clearly what i'm looking for.http://dangerousprototypes.com/docs/Dangerous_DSOjust to learn about analog to digital conversion.The goal is to limit to the analog part of this DSO to realize the wing.BR,Christophe