Wiki suggestion for the GPIO page

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DomoOr1981
Posts: 11
Joined: Sunday 30 July 2017 10:44
Target OS: Raspberry Pi
Domoticz version: 3.8373
Location: Holland
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Wiki suggestion for the GPIO page

Post by DomoOr1981 » Thursday 28 September 2017 14:08

I'd expected members to be able to update the Wiki, but on Domoticz this seems not to be the case.
This warning: "If you do not want your writing to be edited mercilessly, then do not submit it here." scared me away.
I'll hope this subforum is the correct place to make a suggestion.

Might I suggest the following:
1) There is little info about what an "Active low relays" actually means.
2) Perhaps some info about the differences compared to an "Active high relay board" would be nice.
3) Although an "Active high"-board seems more logical to me (now, that is), I got an "Active low"-board delivered. Changing its (unwanted-)behaviour is possible (if one is handy with soldering transistors and resistors), but I choose to accept the (unwanted-)behaviour "that my switched-lights turn on upon boot", after adding a switch-to-off command to the domoticz.sh shell-script. (They also turn on - very shortly - upon shutdown as wel, but this also is acceptable.)
For each of my 4 relays the script now contains three lines (this "BCM-26-example" is for physical pin no.37 on my old rpi B+):

Code: Select all

/usr/bin/gpio export 26 out
sudo sh -c "echo '1' >> /sys/class/gpio/gpio26/active_low"
/usr/bin/gpio -g write 26 1 #turns relay&lightswitch to off.
As always - so I've read all-over-the-web - is the pin-numbering confusing; in the write command I had to use parameter -g to get it to use the BCM_GPIO pin numbering scheme, whereas in other commands (eg export) this numbering seems to be the default.

I hope you'll appreciate my posting.

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