Products > Test Equipment
A High-Performance Open Source Oscilloscope: development log & future ideas
tom66:
There's JESD204B support in the Zynq 7000 series, though only via the gigabit transceivers which are on the much more expensive parts.
I've little doubt that I'll cap the maximum performance around the 2.5GSa/s range - at that point memory bandwidth becomes a serious pain.
I've a coy play for how to get up to 2.5GSa/s using regular ADC chips - it'll require an FPGA as 'interface glue' to achieve but it could be a relatively small FPGA.
Someone:
--- Quote from: tom66 on November 16, 2020, 08:13:55 pm ---Shifting the dots is computationally simple even with sinx/x (which is not yet implemented). It's just offsetting a read pointer and a ROT-64 with an 8-bit multiple, practically perfect FPGA territory. In the present implementation I simply read 0..3 dummy words from the FIFO, then rotate two words to get the last byte offset.
--- End quote ---
Noting that triggers in modern scopes are aligned more finely than the sample rate (interpolation), with the reconstruction and interpolation methods also dependent on the front end characteristics. Expect the rendering speeds to collapse in a software/GPU approach once you put in that phase alignment and sinc interpolation.
In better news if you're going down an all digital trigger route (probably a good idea) then the vast majority of "trigger" types are simply combinations of 2 thresholds and a one shot timer, which are easy enough. That can then be passed off to slower state machines for protocol/serial triggers. But without going down dynamic reconfiguration or using multiple FPGA images supporting a variety of serial trigger types becomes an interesting problem all of its own.
Circlotron:
This takes "home made" to a whole new level!
My suggestion would be to have an A/D with greater than 8 bits. This would set it apart from so many other "me to" scopes. I'm sure there is a downside to this though - price, sample rate limitations etc. Also, if there is to be a hi-res option, maybe have a user adjustable setting for how many averaged samples per final sample or however it is expressed. I love sharp, clean traces. None of this furry trace rubbish!
Someone:
--- Quote from: Circlotron on November 16, 2020, 11:28:06 pm ---This takes "home made" to a whole new level!
My suggestion would be to have an A/D with greater than 8 bits. This would set it apart from so many other "me to" scopes. I'm sure there is a downside to this though - price, sample rate limitations etc. Also, if there is to be a hi-res option, maybe have a user adjustable setting for how many averaged samples per final sample or however it is expressed. I love sharp, clean traces. None of this furry trace rubbish!
--- End quote ---
Part of the fun of open source is you can ignore the entrenched ways of doing things and offer choices to the user (possibly ignoring IP protection along the way). A programmable FIR + CIC + IIR acquisition filter could implement a wide range of useful processing.
dougg:
A suggestion: replace the barrel connector (for power I assume) and the USB type A receptacle with 2 USB-C female receptacles. Both USB-C connectors should support PD (power delivery) allowing up to 20 Volts @ 5 Amps to be sunk through either connector. This assumes that power draw of your project is <= 100 Watts. If the power draw is <= 60 Watts then any compliant USB-C cable could be used to supply power. If the power draw is <= 45 Watts then a product like the Morphie USB-C 3XL battery could be used to make the 'scope portable. Dual role power (DRP) would also be desirable, so if a USB key is connected to either USB-C port then it could source 5 Volts say around 1 Amp. A USB-C (M) to USB-A (F) adapter or short cable could be supplied with the 'scope for backward compatibility. I guess most folks interested in buying this 'scope will own one or more USB-C power adapters, so it frees the OP from needing to provide one (so the price should go down). Many significant semiconductor manufacturers have USB-C offerings (ICs) with evaluation boards available (but not many eval boards do DRP).
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