...and that kit is damn expensive.
Edit: It doesn't work with external GPIB adapter in parallel with the extension for me. You may want to look at the code and see if all the lines are high impedance/inputs while waiting for buttons press/serial communication.
I can make some suggestions, if you are open to improvements.
1. Timeout so it doesn't stay there forever waiting to select AUTOHOLD, etc.
2. Instrument GPIB address auto detection so we're not stuck with address 23 and we don't have to set it manually in the extension board. You can save it in EEPROM and validate it at power up.
Could you add some background, why do you think it would be useful?
If you mistakenly press the SRQ key, I think, it's faster to cycle through menu instead of waiting.
I guess this is meant for installations where you just don't want to use the USB interface at all.
It can be done, but it's a bit more complex than I like it...
By the way, I made it to exit the continuity tester by switching the measurement function.
In CONT mode, if I don't probe anything for awhile, probably about 10 minutes, the display goes blank. That's a feature the instrument if the display isn't updated for about 10 minutes. Please look at "D3text" command. Probably you don't update the display if nothing changes.
Did you upload the hex somewhere?
Looks like it's a good idea to add a gate pull-down resistor for the buzzer driver mosfet. It gets quite warm then atmega pin is high-Z.
Looks like it's a good idea to add a gate pull-down resistor for the buzzer driver mosfet. It gets quite warm then atmega pin is high-Z.I didn't expect that output to be hi-Z but I guess that's how you turn the buzzer on and off, from DDR register. Can you add one line of code to make PB2 digital output once you turn off the buzzer and then PWM output again when you turn it on?
Should be an easy patch to do on the actual pcb's you have
Kirill,
I still see the old files on Github, the .eep and .hex are dated Aug 2018. Not that I want to update now, I'm very happy with this version. I will probably play with it once I install the USB cable that I ordered from Evilbay.
So happy that HP3478A became my go to meter for every day measurements:
- Buzzer response is very fast, at par with Fluke.
- Autohold is very fast and stable with 3 or 4 digits and reasonably fast with 5 digits.
- Min/Max works well.
I have two more suggestion for improvement:
1. Latch buzzer - minimum buzzer time. Fluke does that.
2. EEPROM autoinit - Initialize the EEPROM after a new part is programmed or after an upgrade that adds new EEPROM addresses/content. This may be harder to implement but I don't think you use many EEPROM variables.
The firmware uses the default parameter value when it sees FF's instead of something valid. This should work during upgrade as soon as parameters are not rearranged or interpreted in a different way.
Since Arduino bootloader doesn't program EEPROM...
Kirill,
The buzzer doesn't work for me with Ver 1.2 and I tried both EEPROMs, I'm back to Ver 1.1. I use internal driven (DC) buzzer.
I just uploaded r1.2.1, it hopefully fixes the problem.