project: extending HP3478A functionality

[kirill_ka]

As someone may have noted The hp3478ext has a temperature measurement function.
It only supports 1kOhm 3850 ppm/K RTDs. The constants for which are hardcoded.
Yesterday I found a source of cheap sensors: https://aliexpress.com/item/32872179878.html
They look similar to the Honeywell sensor (700-102BAB-B00) that I have.

[momoFukushima]

Hello kirill-ka,

I recently bought a used 3478A and found this very interesting topic that can expand the functionalities as well as the prologix compatibility during searching various knowledge about this tool. Visiting the Git-hub, I noticed the source program has been updated very recently but looks like the binary has not been updated yet. I would be appreciated if you upload the updated binary, since I am not familiar with the compiling at all.

Thanks

[Tj138waterboy]

Not sure if this has been asked on other post but will the artag style adapter work and or does anyone have the gerber for a known working pcb layout.

[kirill_ka]

I would be appreciated if you upload the updated binary, since I am not familiar with the compiling at all.

Hi,
There aren't serious changes, but here you go: https://github.com/KIrill-ka/hp3478ext/releases/tag/r2.2
 

• fixed ++ver command to actually show a version
• added 250ms delay before trying to initialize the HP3478A during startup
  Attempt to read from the HP3478A too early caused a harmless error message to be displayed on the second try.
  
• some minor error handling modifications

[kirill_ka]

Not sure if this has been asked on other post but will the artag style adapter work

Sorry, I'm not quite sure what do you want.
Do you mean using some AR488 hw to run hp3478ext or what?

[momoFukushima]

Thank you very much for binary update, kirill_ka.

[Tj138waterboy]

For the purpose of plugging into gpib externally. I was thinking that would work the same from my understanding. Pretty much just needs 5v supply to arduino and buzzer.

[kirill_ka]

For the purpose of plugging into gpib externally. I was thinking that would work the same from my understanding. Pretty much just needs 5v supply to arduino and buzzer.

The external connection is not a problem. The cheap atmega328p board+USB2UART+connector+bunch of wires will do the job.
AR488 hardware will not work straight away as it uses different pin assignments (at least).

[mcj7247]

For the purpose of plugging into gpib externally. I was thinking that would work the same from my understanding. Pretty much just needs 5v supply to arduino and buzzer.

The external connection is not a problem. The cheap atmega328p board+USB2UART+connector+bunch of wires will do the job.
AR488 hardware will not work straight away as it uses different pin assignments (at least).

Would it be possible to remap the pins to a custom layout in the AR488 FW to align with the HP3478A Control Software?

[kirill_ka]

For the purpose of plugging into gpib externally. I was thinking that would work the same from my understanding. Pretty much just needs 5v supply to arduino and buzzer.

The external connection is not a problem. The cheap atmega328p board+USB2UART+connector+bunch of wires will do the job.
AR488 hardware will not work straight away as it uses different pin assignments (at least).

Would it be possible to remap the pins to a custom layout in the AR488 FW to align with the HP3478A Control Software?

Everything's possible... Can you provide desired pin assignments?
Do you mean hp3478ext by the "Control Software" or something else?

[mcj7247]

Everything's possible... Can you provide desired pin assignments?
Do you mean hp3478ext by the "Control Software" or something else?
[/quote]

I think I may have the various tools confused and apologize if I do. I think I'm referring to the HP3478A Control Software app developed by Steve1515, lmester etc.

[Tj138waterboy]

I just re-read entire thread and issue that seems to prevent using ar-tag adapter would be from post #105 the piezo/speaker pin. Also a reply from lmester pointed out you can't run both programs at same time, as from what I can tell all commands for the functions of 3478ext are manual button presses whereas the software mcj7247 shows in previous post is what I currently have been using and is ui controlled. It doesn't seem that the arduino sketch would allow both functions to work in unison due to the pin assignments as well as the user interface for the 3478 control software mcj7247 shows would have to be possibly recoded if you wanted a display.

[Tj138waterboy]

Also im not even sure a usb powered arduino could drive a speaker directly while performing as a gpib adapter. Never measured current draw from piezo.

[kirill_ka]

I just re-read entire thread and issue that seems to prevent using ar-tag adapter would be from post #105 the piezo/speaker pin.

Correct. If the PB2 (or PB1) pin is not available, then more modifications required for the hp3478ext to work. However if the variable tone buzzer is not essential, the firmware can be modified to use any digital pin for the buzzer.

It doesn't seem that the arduino sketch would allow both functions to work in unison due to the pin assignments as well as the user interface for the 3478 control software mcj7247 shows would have to be possibly recoded if you wanted a display.

The lmester's "HP3478A instrument control software" does work with the hp3478ext firmware. It has nothing to do with the pin assignments. You can't simultaneously use the PC software and the extended functions (relative, continuity, etc.). Once you exit the PC software, the extended functions "assigned" to the SRQ key will be restored.

[kirill_ka]

Also im not even sure a usb powered arduino could drive a speaker directly while performing as a gpib adapter. Never measured current draw from piezo.

An active buzzer can be driven directly by the MCU pin. I recommend adding a resistor in series.
The direct connection of a piezzo speaker will also work with a current limiting resistor, but the volume would be quite low.
A FET driver is recommended anyway.

[belzrebuth]

So now that this project seems mature enough shouldn't there be a PCB gerber available for it?
Just saying it would be far more tidy/safe to have this assembled outside and only do the absolute necessary soldering inside the instrument.
As I understand it Miti already done a PCB for it, maybe sharing it would be a good idea?

[bywqdq]

Provide an idea to display the time when the multimeter is not operating. Add RTC to the circuit.

[kirill_ka]

Provide an idea to display the time when the multimeter is not operating. Add RTC to the circuit.

Hi bywqdq, welcome to the forum!

That would be so complex and inconvenient with an Atmega 328p.
However if you provide some alternative hardware, I might do something about it

[bywqdq]

I make one.

[yo0]

The hex files are compatible with the Arduino nano?

I ask because I wired per the pin table in the GitHub to the conector but no luck.

If not what is needed?

Best regards

Pio

[kirill_ka]

Hi,
Does it respond via serial (USB) interface? If it does, the second thing to check is the GPIB address.

[yo0]

Hi,
Does it respond via serial (USB) interface? If it does, the second thing to check is the GPIB address.

thank you,

no response, and the address is set #23, i triple check the wiring,

perhaps defective nano? it can be read, write and verify with avrdude and avrdudess

thank you in advance.


Pio

[kirill_ka]

It should respond to UART commands without any connections. Just the bare board.

[yo0]

It should respond to UART commands without any connections. Just the bare board.

I think yes it does. If I send text over serial monitor it appears in the console. I don't have experience with Arduino, sorry

I needed load a serial sketch to do that

ps.

i think maybe the problem is the wiring, do you know which pin at the external dmm connector is #1?, i mean seeing it frontally , the red wire at the ribbon cable usually mean pin 1 as far i understand, but.. seeing the schematic pin 1 at the socket is connected to ground, that don't make sense to me. or at least hp mount the internal connector backwards to avoid the ribbon be too near the transformer. in that case pin 1 really is at the other extreme of the socket (i mean near to the notch of the socket, usually pin 1 is at the notch side). or the socket is inverted, i am confused.

just an idea 

Best regards

Pio

[kirill_ka]

It should respond to UART commands without any connections. Just the bare board.

I think yes it does. If I send text over serial monitor it appears in the console. I don't have experience with Arduino, sorry

I needed load a serial sketch to do that

It's good to know, that the UART works. But you'd get the response from the hp3478-ext firmware. Just to know that it's loaded and works.
It should respond with the <GPIB> prompt.

The connector pinout is standard. Just google "GPIB pinout". You'd find the pictures of the connector with the pin names and numbers.