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FNIRSI-1013D "100MHz" tablet oscilloscope

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I was just wondering ...

We know this thing tops out at about 20MHz bandwidth. Would it be worth modding it with a capacitor to limit the input to around that frequency and help it keep things together at higher frequencies? (ie. not show rubbish on screen)

I don't think that will help. The crap is in the FPGA even if the input is a pure sine below the 20MHz. Less frequent but still there. The only way to really improve this thing is to redesign the front end and the FPGA programming. And then still for a proper signal representation it needs to be kept below 40MHz since it only has a max of 200MSa/s per channel.

Not a bad thing because 40MHz is good for many hobby projects.

With redesigning the front end I mean calculate new values for the resistors and capacitors to give it a better sensitivity range and raise the low pass filter point to suite the 40MHz if possible. Have the software do more range scaling and sacrifice one or two bits in resolution. Accept it to never be a precise instrument to do spot on measurements.

But first of all getting an open source firmware working on it as is, is the first hurdle to take. Getting close, but still a lot to do.

I am really looking forward to replacing the stock firmware with the results of your hard work.

I previously used a DSO203 which really benefited by using the open source firmware; much better than the stock version.

When I need extra sensitivity issue I use a battery powered home built front end 2 channel pre-amp. One channel based on OPA355 (x10) has a bandwidth of ~ 15MHz and the other (transistor based) for audio type work, is switchable x10, x100 with a bandwidth ~5MHz.

Thanks for your skill and efforts on this.

@btidey, your welcome.

And your idea of an external amplifier is also a solution to crank up the sensitivity.  :-+


--- Quote from: morris6 on November 21, 2021, 07:26:04 pm ---What do you think, is this a genuine Altera Cyclone IV?

--- End quote ---
The part number found in the programming stream by tv84 is 0x020F1, that checks with the IDCODE for EP4CE6 (Cyclone IV Device Handbook, Volume 1, table 10-2).

How about a JTAG connection? A 10 pin IDG header and a few wires later: As expected, Quartus IDE programmer (USB Blaster) does not recognize this as an Altera (Intel) EP4CE6. The JTAG Chain Debugger does find a device: UNKNOWN_18006C31.

Before going into OpenOCD to try a connection over JTAG with the FPGA I connected  with Flashrom program to the FPGA Flash part. On my board that is a Zbit ZB25VQ80. Connecting with the Flashrom program failed, unknown chip. But, it found a manufacturer and part ID. I updated the flashrom flashchip.c and -.h files with this chips info and now at least reading the chip worked. For comparison the file is attached.

Next is comparing the content of this flash with the bit stream of the flash for the real Altera Cyclone IV...


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