Digital Out Pins briefly switch to HI when booting

[datahaki]

We noticed that when we power up RevPI [Compact], all 8 DIGITAL OUT pins switch to HI for a brief period, perhaps 5-10[ms].
This happens during every boot.

Is there a way/setting to ensure that the DIGITAL OUT pins remain LO (=0[V]) always unless commanded otherwise?

[Davide]

This also causes me problems, risking opening valves at the wrong time.
Has anyone succeeded in resolving it?

[ctf]

I too see this behavior with my RevPi Compact. Some feedback and help on this would be great.

[giuseppe]

Hello all,

yes, this is unfortunately a known issue.
We are currently working on this bug.

Unfortunately, we can't influence the behaviour.
The output pins on the Compact come directly from the compute module, and we have no influence on this behaviour at boot time.

Mit freundlichen Grüßen | Best regards
Giuseppe Pagano | Technical Support

[vbezos]

Hi, Just got a new RePi Compact and have the same problem.
Is there a fix for that?

[nicolaiB]

Hi

Could you please test if the following fixes the problem for you?

1. Download the attached archive and extract it
2. Copy the file to your revpi as `/boot/dt-blob.bin
3. Reboot

Nicolai

[vbezos]

Hi Nikolai,

Thanks for the fast response!
This seems to have fixed the digital output behavior in cases of RevPi reboot/boot but not when it is powered ON.
So previously we observed two instances of DO getting all High, once when we supplied power to the RevPi and once a bit after during the booting sequence.
Now we only observed it once at power ON.
Is there a fix for that also?

Thanks in advance
Vaggelis

[nicolaiB]

Do you actualy measure output voltage during power on or just observe flickering of the output LEDs?

[vbezos]

No, the 24V relays connected to the DO are also energized while the LEDs flicker.

[nicolaiB]

I will have another look. At the moment I'm not able to reproduce a measureable glitch on power on. Which kind of relais are you using?