Digital oscilloscope Project

[ME]

qtdso sreen resolution

I only have a laptop, and laptops have no VGA inputs, only an output :?

What about connecting it to a normal TV through the CVBS video input?
It is the same input as in a CGA monitor.
Most people have a TV.

I have an old CGA monitor too, with both CVBS and RGB input.

 

[martingn]

oscilloscope digital project

Davorin,

I think that develop the "proto" switching the only VGA between DSO and the PC could be very exhausting.
By the other hand, we dont need to write PC code. Couldnt we just log sampled data in a file and see it in Excel? Its just for test not for final use.

Most vendors doesnt send samples to my country
Anyway, wait a few months could be very boring.
I think that the best option is to choose a cheap FPGA to meet the design spec , and that everyone could easylly obtain.

We need to decide what FPGA to use.

regards,
MArtin

 

[monnoliv]

self-made oscillograph scheme lcd

Hi all,

Just this post to invite you for seeing the second revision of the DSO with english translation !!!
I invite you to make lot of suggestions. I tried to keep the two options on the way (PC linked and handheld).
Here is the link:
**broken link removed**

See you,

 

[ME]

oscilloscope on a chip

Hi all,

Just this post to invite you for seeing the second revision of the DSO with english translation !!!
I invite you to make lot of suggestions. I tried to keep the two options on the way (PC linked and handheld).
Here is the link:
**broken link removed**

See you,

Thanks for the quick translation :spoko:

There is a wrong link at page two: **broken link removed**

The link called 'next page' points to the page you are already on instead of page 3.
It is only if you click at the English text, if you click at the french text it is ok. For some reason it is divided in two different links instead of just on long link with text in both French and English, just like the 'previous page' link is.

 

[martingn]

digital oscilloscope diy

Monnoliv,

I call that working fast!
Would you consider a cheaper FPGA?
What do you think about the simple "proto"?

regards,
MArtin

 

[ME]

digital oscilloscope (dso) scope parts list

I invite you to make lot of suggestions.

I have a suggestion for an improvement of the USB interface.
I think you should replace the 2nd generation USB chip, FTDI FT232BM with the brand new 3rd generation USB chip FTDI FT2232C Dual USB UART / FIFO.

INTRODUCTION
The FT2232C is the 3rd generation of FTDI’s popular USB UART / FIFO I.C. family. This device features two Multi-Purpose UART / FIFO controllers which can be configured individually in several different modes. As well as a UART interface, FIFO interface and Bit-Bang IO modes of the 2nd generation FT232BM and FT245BM devices, the FT2232C offers a variety of additional new modes of operation, including a Multi-Protocol Synchronous Serial Engine interface which is designed specifically for synchronous serial protocols such as JTAG and SPI bus.

FT2232C has two i individually configurable UART / FIFO channels, while FT232BM only had a single UART channel.
This means that you can configure channel A of the chip to JTAG interface, while channel B is configured for UART.
The you can use channel B as you do now for connection to the MCU, while channel A can be connected to the FPGA JTAG interface.

Then you don't need any external JTAG dongle

When using the DSO in the 'PC Version' without 'configuration memory', then you can load the configuration program to the FPGA directly from the PC via the FT2232C JTAG interface, without using the FT2232C UART interface thru the MCU. This will also make the configuration program load faster and probably much simpler programming on both PC and MCU side.
You might not even need a MCU at all if you can progran the FPGA from JTAG. Then you can júst receive the measurement data directl from the FPGA connected directly to the FT2232C UART.
This could save some money and programming and you need fever parts for the 'PC Version' DSO.

The JTAG interface can be made optically isolated like your UART port already is.

If you use a MCU with JTAG interface, like the ATmega 16, 32, 64 or 128 AVRs, then you can also connect this to JTAG for on-chip-debugging.

 

[monnoliv]

digital oscilloscope sematic

The link called 'next page' points to the page you are already on instead of page 3.
It is only if you click at the English text, if you click at the french text it is ok. For some reason it is divided in two different links instead of just on long link with text in both French and English, just like the 'previous page' link is.

It's ok now, thanks.

Would you consider a cheaper FPGA?
What do you think about the simple "proto"?

We can use a cheaper FPGA (the EP1K10) but then we only have 512 x 8 (bits) x 2 (channels) of FIFO memory instead of 1024 x 8 x 2 (the EP1K30, with Quartus II I've already made a check for the available memory to store the samples, I used the FIFO megafunction). I checked (roughtly) the pinout of the EP1K10, EP1K30 and EP1K50 devices (TQFP144 package) and they have the same pin assigment. Then one can choose later the final device.
About a prototype, I've no Idea, will the prototype be more simpler than the scope logic board ? You have to solder a TQFP 144 package, then you have to make a PCB, no? Why not make a PCB with a few more components and have the skeleton of the scope ?

ME, the FT2232C is very interresting indeed. Ok, I'll check for implementation.

Regards,

 

[monnoliv]

oscilloscope analog front-end

I forgot to ask you all, what is your programming enviromnent to write PC code? I use Cpp builder 4.
bye,

 

[se06745]

pc scope project

Hi!

1) The analog hardware of bitscope DSO is important in order to calibrate the equip. Is very good!!!

2) Using a direct VGA interface is "easy" for a limited code to show a signal only. With PC interface you can calculate easyly and print a lot of information about de siganl like a freq, Vp, FFT....

3) I think that you don´t need a ultra fast PC interface USB. You need to get de High Freq signal. The monitor not print 50.000.000 signal variations at 1 second. You capture the 20MHz siganl (for example) and print it. A simple RS-232 o USB 1.0 is enought.

4) To do a fast sample and hold you need a FPGA (with internal memory) or a FIFO with CPLD. ¿Do you know VHDL or Verilog?

5) Your input Z = 1Mohm (minimum) and 20pF (more or less) for especific applications you can use Z = 50 or 70 ohms (to match impedances)

6) The onlyu problam that I have is accept a 100v or more input voltage. If I use digital switches to divide 1:10 or 1:50 .... these switch accept +-5v imput. (only solution is use a mechanical swith resistor divisor)

Thanks for all!!!

 

[pisoiu]

homemade dso

Hi!

6) The onlyu problam that I have is accept a 100v or more input voltage. If I use digital switches to divide 1:10 or 1:50 .... these switch accept +-5v imput. (only solution is use a mechanical swith resistor divisor)

Thanks for all!!!

Well...not entirely true. You can use photomos relays. Some models accept 400V, and if you take a look at tektronix mainboard picture I previously posted in this topic you'll see some photomos relays there. They are used to switch ac/dc modes at input. Also, there are some fet in opamp buffers from analog devices which have protection diodes at input, and with a limiting resistor at input they can sustain voltages of hundreds (ad8065).
Also, somewhere upwards it was stated that usb powered PC based DSO cannot be isolated from PC ground. Well..here is an idea: a small isolated buck-boost smps can deliver power for analogic circuits and a FT232/245BM which is connected on a side at USB can be connected on the other side to uC/FPGA with optocouplers, thus achieving desired isolation.

/pisoiu

 

[martingn]

usb scope avr

Hi all,

I think 512x8x2 its ok for a handheld DSO.

regards,
MArtin

 

[ME]

a26 lambo student liu se

About a prototype, I've no Idea, will the prototype be more simpler than the scope logic board ? You have to solder a TQFP 144 package, then you have to make a PCB, no? Why not make a PCB with a few more components and have the skeleton of the scope ?

You should only make a protoype if you already have an evalution kit with the FPGA mounted.
Otherwise you should just make a complete PCB layout, you don't have to mount all components to begin with.

ME, the FT2232C is very interresting indeed. Ok, I'll check for implementation.

It should be easy to upgrade to the new 3rd generation FTDI chip, same housing and sorrounding components.

Would you consider a cheaper FPGA?
What do you think about the simple "proto"?

We can use a cheaper FPGA (the EP1K10) but then we only have 512 x 8 (bits) x 2 (channels) of FIFO memory instead of 1024 x 8 x 2 (the EP1K30, with qu@rtus II I've already made a check for the available memory to store the samples, I used the FIFO megafunction). I checked (roughtly) the pinout of the EP1K10, EP1K30 and EP1K50 devices (TQFP144 package) and they have the same pin assigment. Then one can choose later the final device.

Regards,

The only two Altera FPGAs I could find for sale to private persons in my country is EP1K30TC144-3 and EP1K50TC144-3 at www.farnell.com.
They are very expensive:
EP1K30TC144-3 costs € 45 ($ 56) incl. VAT, excl. shipment
EP1K50TC144-3 costs € 56 ($ 68) incl. VAT, excl. shipment

Farnell haven't got EP1K10.

Does anyone know of a cheaper place to buy theese FPGAs within the European Union :?:
Where do you buy the Altera FPGA monnoliv and how much do you have to pay for the ACEX's? Or do you get it thru your company for free?

 

[monnoliv]

pc oscillascope schamatic diagram

Hi all,
I'll implement soon (now my website is down and I don't know why) the FT2232C from FTDI. One channel (A) will serve as a JTAG connector for FPGA, the other channel (B) will serve for the command (receive) datas for (from) FPGA (this channel B will be configured as a fast sync serial, and the decoder will be a small part of FPGA), then no more need of a µC !!! (thanks ME) at least for the PC version. Then I'll remove one connector, the remaining one will serve for the handheld version (display - keyboard - µC and battery).

1) The analog hardware of bitscope DSO is important in order to calibrate the equip. Is very good!!!

Ok, I'll check to implement the calibration.

I think 512x8x2 its ok for a handheld DSO.

No pb, let's configure this device with all the function to see if it works

Does anyone know of a cheaper place to buy theese FPGAs within the European Union
Where do you buy the @ltera FPGA monnoliv and how much do you have to pay for the ACEX's? Or do you get it thru your company for free?

EBV:
EP1K10TC144-3 Price: 11.47 MOQ: 60
EP1K10TC144-2 Price: 15.57 MOQ: 60

EP1K30TC144-3 Price: 16.39 MOQ: 60
EP1K30TC144-2 Price: 22.13 MOQ: 60

(MOQ: Minimum Order Quantity)

Arrow has also the pieces but it's more expensive (no MOQ) as I saw.

It's not sure but perhaps I'll be able to buy 60 pieces and sell one piece at a time for each guy who is interrested (+shipment). The same for other pieces that are difficult to find in small quantity.

See you,

 

[ME]

scope avr

Does anyone know of a cheaper place to buy theese FPGAs within the European Union
Where do you buy the @ltera FPGA monnoliv and how much do you have to pay for the ACEX's? Or do you get it thru your company for free?

EBV:
EP1K10TC144-3 Price: 11.47 MOQ: 60
EP1K10TC144-2 Price: 15.57 MOQ: 60

EP1K30TC144-3 Price: 16.39 MOQ: 60
EP1K30TC144-2 Price: 22.13 MOQ: 60

(MOQ: Minimum Order Quantity)

Arrow has also the pieces but it's more expensive (no MOQ) as I saw.

It's not sure but perhaps I'll be able to buy 60 pieces and sell one piece at a time for each guy who is interrested (+shipment). The same for other pieces that are difficult to find in small quantity.

See you,

Sounds like a good idea.
It's always much cheaper to buy components in big quantities than just buying a single component.
Maybe you should order a little stock of PCBs for the project when it is finished to sell with the special components. It's much cheaper to get the PCBs made in one big order than 50 seperate orders.
You can even start a little webshop with Paypal payment or something like that if the project becomes a succes.

I don't think you can buy at the distibutors Arrow or EBV as a private person.
I know Arrow USA has a web shop, but the shipment and handling costs for international orders are redicolous high and on top of that you have to pay import taxes and VAT. The FPGA will end up being more expensive than a complete handheld scope.

 

[ME]

make pcb avr multikitb

I think you should add 8-, 16- or 32- bit Logic-analyzer functionality to the DSO too.
The connections to the FPGA could be made via a DSUB connector or a Centronics connector.
There is something similar at the Bitscope.

------------------------------------------------------------

Check out this new ADVANCED PERSONAL SCOPE 240MS/s:
http://www.velleman.be

 

[monnoliv]

project digital oscilloscope

I think you should add 8-, 16- or 32- bit Logic-analyzer functionality to the DSO too.
The connections to the FPGA could be made via a DSUB connector or a Centronics connector.

Good idea, but any suggestion for the protection of FPGA inputs ?

Check out this new ADVANCED PERSONAL SCOPE 240MS/s:
http://www.velleman.be

It's in fact a 2x 60MS/s

 

[ME]

dso oscilloscope project

I think you should add 8-, 16- or 32- bit Logic-analyzer functionality to the DSO too.
The connections to the FPGA could be made via a DSUB connector or a Centronics connector.

Good idea, but any suggestion for the protection of FPGA inputs ?

Here's the BitScope schematic for Logic Analyzer input:
https://www.bitscope.com/design/hardware/pdf/Bs11-3.PDF

74HC573 are connected between inputs and CPLD.
10 kohm - 1Mohm resistor termination network are also connected to all inputs. Value depends of if the Active POD is connected or not.
With this desing you will only damage the 74HC573 instead of the CPLD / FPGA.
You could aslo connect transorb / transient voltage suppression diodes to 5V and GND at the inputs.
Here is a list of Transient Voltage Suppressors:
**broken link removed**

I think you should make every 2nd pin in the socket GND to improve shielding of the flatcable connected.
You can also use an Flatcable-connector instead of DSUB if you prefer.
But DSUB are probably easier to mount in a cabinet and more roboust.



Check out this application note from Xilinx too, this is probably the best way to design the input stage and protection:
https://www.xilinx.com/bvdocs/appnotes/xapp368.pdf
It's about how to design a Handheld Pocket Logic Analyzer.

Input Protection: Responsible for protecting the input comparator from excess voltage and
current. This protection scheme usually consists of a current-limiting resistor and a dual mode
transorb diode. This input protection circuit will have limits to its protection abilities. The user
should be careful not to apply an input voltage level that exceeds these limits. Input protection
was not implemented in this prototype.

 

[se06745]

dso 220

Hi!

The photomos relays, it's true I didn't remember!! Thank's. 8)
But what is the frequency response of photomos relays. The maximum frequency input signal???

Best Regards!

 

[pisoiu]

how make digital oscilloscope

Hi!

The photomos relays, it's true I didn't remember!! Thank's. 8)
But what is the frequency response of photomos relays. The maximum frequency input signal???

Best Regards!

Tektronix TDS2014 use NAIS AQY214 as AC/DC input switch, and it have 100MHz input bandwidth.

/pisoiu

 

[Ace-X]

digital oscilloscope fpga

Why not to use ready development board? For example, many times discussed here Virtex2Pro board from Memec. 149$, V2Pro4 FPGA (more than 500 Kbits of internal BlockRAM), embedded PowerPC processor, USB and RS232 ports. It will allow to forget about all this troubles with PCB and soldering and concentrate on real DSO design.

Ace-X.