PI-GB Design

[algan]

Hi Carl, can you tell me where in the code I need to correct the Pulse-4 Firmware (PI-GB) code, so I can try to test the TDI GB as well? For example
at a frequency of 3200 hertz. Thank you.

[Carl-NC]

Timing parameters are in Pulse.c:



I would also disable the frequency control pot so you don't get into thermal trouble; comment out lines 72 & 73 in PulseADC.c:

[pechkata]

Hello Carl-NC
Everything works fine after I started the feed pump according to this scheme...
But now when I turn on the 74HCT4316 switch it changes the sound and changes the power supply...
Is there a way to fix this...?

https://www.youtube.com/shorts/gn4ItNZ9rDY

[pechkata]

Здравей Carl-NC
Има ли начин да поправя това...?

[algan]

Hi Carl, this board also doesn't work for me and the sound starts to drop and break and the threshold potentiometer can't work correctly when I turn on the 74HC4316 integrated circuit. What do I need to change in the code to make it work? Thanks

[Detectorist#1]

Hi algan and pechkata,
The version 2.01 of GBPI schematic haven't chance to work properly. The power of PIC is between 0V and minis 5V but 74HCT4316 needs control pulses between 0V and +5V. Only way to fix this problem is to add voltage converters in all 4pcs. control signals for 74HCT4316. It is not possible to supply PIC between +5V and GND because for producing of +5V you need pulses from PIC. (the question is: Which came first - the chicken or the egg? ).

[Detectorist#1]

Have one more variant to fix this problem - to use 74HC4316 from NXP and connect GND pin to minus 5V. This will avoid the need of voltage level translators. But this is not easy - this IC is produced from NXP only in SOIC-16 case. You will need SOIC-16 to DIP-16 adapter (this type of adapters haves bigger size than DIP-16 case and this is a problem - possible conflict with near parts of the board). The 74HC4316 from TI allows max voltage Vcc-GND of 7volts only and is not suitable for this variant.

[Detectorist#1]

First, move the GND pin on 74HC(T)4316 from GND to minus 5V rail. It is possible that this will fix the problem (if no overloading of +5 rail occurs)

[pechkata]

Hi algan and pechkata,
The version 2.01 of GBPI schematic haven't chance to work properly. The power of PIC is between 0V and minis 5V but 74HCT4316 needs control pulses between 0V and +5V. Only way to fix this problem is to add voltage converters in all 4pcs. control signals for 74HCT4316. It is not possible to supply PIC between +5V and GND because for producing of +5V you need pulses from PIC. (the question is: Which came first - the chicken or the egg? ).

Hello Detectorist#1
Maybe you mean like in this diagram.

[Carl-NC]

Sorry for the delayed response. My original PCB was a hacked-up mess so I built a new circuit from scratch. There is an error in that both pins 7 & 8 of IC3 should be connected to VEE, not ground. This was done correctly on my original board and then I copied it incorrectly to the Rev2 PCB. Furthermore, IC3 needs to be an HCT type, not HC.

But there's a slightly easier fix. Since the PIC runs on 0/-5V this circuit really does not need the 4316 chip, a 4066 will work just fine. And the 4066 can directly replace the 4316 by leaving the bottom two pins (8 & 9) empty. Pin 7 will still need to be moved to VEE, for this bend the pin so it is not soldered in the hole and jumper it to IC2-pin4. Also, use the 74HCT4066. In doing this my board is working. I will make corrections to the schematic & Gerbers and post new versions. Apologies to all.

[pechkata]

Hello Detectorist#1
Something else worries me - on this graph, the blue and red rays are DELAY.
They should be after the pumping pulse.

[Carl-NC]

Hello Detectorist#1
Something else worries me - on this graph, the blue and red rays are DELAY.
They should be after the pumping pulse.

The are the EFE cancellation samples so they appear just before the TX pulse. They are correct.

[pechkata]

Hello Karl-NC
Yes - I swapped the probes on the oscilloscope.
Everything is fine with the PIC16F18426

[algan]

Thanks, Carl, I will wait for the corrections and new gerberas and transfer all the elements from this board to the new board with 74HCT4066.

[pechkata]

Hello
Everything is OK.
I released it with 74HC4316

Thanks Carl-NC