MMDVM_HS_HAT Held in reset

MMDVM_HS Hat hardware
Post Reply
G0ELM
Posts: 10
Joined: Wed Jan 16, 2019 10:05 pm

MMDVM_HS_HAT Held in reset

Post by G0ELM »

Hi,
I have 2 Jumbospots.
Recently updated both of them.
One works fine, the other has a strange fault.
When it boots the reset line from the pi to the Jumbsoot board stays a a logic 0 and holds the modem in reset.
If I issued a pistar-mmdvnhshatreset from a SSH command window everything works.
It is reproducible every boot.
If I swap the modem board then the fault follows the modem board not the Pi.
Is the reset pulse to the board too fast when starting up?
Everything worked ok before the firmware update.
Can I resolve the issue?
Any comments welcome.
Regards
Phil
M1DNS
Pi-Star Team
Posts: 1388
Joined: Thu Apr 05, 2018 5:30 am

Re: MMDVM_HS_HAT Held in reset

Post by M1DNS »

Have you tried running the update agn a 2nd time on the 'faulty' board?

Sent via smoke signals from my SM-G935F M1DNS (Admin)

Andrew M1DNS.
Pi-star Admin Team.
G0ELM
Posts: 10
Joined: Wed Jan 16, 2019 10:05 pm

Re: MMDVM_HS_HAT Held in reset

Post by G0ELM »

Yes, I did try an update and after that even a pistar-mmdvmhshatreset wouldn't make the Hat board work.

However I have solved it!
Looks like the defaults for the GPIO lines have changed in the Pi updates.

So I have now put in the /boot/config.txt file the following line

gpio=21=op,dh

This sets the gpio line to the Hat board high, which is connected to the processor reset on the Hat board.
All boots fine now.
Regards
Phil
User avatar
G8SEZ
Posts: 553
Joined: Fri Apr 13, 2018 8:26 pm

Re: MMDVM_HS_HAT Held in reset

Post by G8SEZ »

That's odd, since you said that the fault followed the HAT I would have expected this to need to be applied to both Pi boards unless there was a delay between any change of the Pi OS files.
--

Brian G8SEZ
M1DNS
Pi-Star Team
Posts: 1388
Joined: Thu Apr 05, 2018 5:30 am

Re: MMDVM_HS_HAT Held in reset

Post by M1DNS »


G0ELM wrote:Hi,
I have 2 Jumbospots.
...

It is reproducible every boot.
If I swap the modem board then the fault follows the modem board not the Pi.
....

Regards
Phil

Yep, ur applied fix seems strange given what youve wrote here above.





Sent via smoke signals from my SM-G935F M1DNS (Admin)

Andrew M1DNS.
Pi-star Admin Team.
G0ELM
Posts: 10
Joined: Wed Jan 16, 2019 10:05 pm

Re: MMDVM_HS_HAT Held in reset

Post by G0ELM »

I have identified the issue with the MMDVMHSHAT in question.
I cut the PCB track connecting the 10K pull-up resistor to the reset input of the STM32 processor on the MMDVMHSHAT board, having removed the 100nF capacitor to make sure that wasn't leaking and the resistance of the reset pin to ground when off measured 2.5k. I compared this to another MMDVMHSHAT and that was around 1M with the components (10k pull-up and 100n decoupler) in circuit on that board.
If you work out what the potential divider between 2.5k and 10k pull-up to 3.3v that's around 0.6 volts which is what I was measuring when system was on, keeping the MMDVMHSHAT in reset.
So my fix to make GPIO 21 on the Pi output high in the config.txt file over comes this issue and allows the MMDVMHSHAT to run.
So it's not an issue with the pi-star updates but a fault with the MMDVMHSHAT. I suspect possible static damage but still allows the reset to function.
Regards
Phil
Post Reply