Relais are inverse

[Kunstflieger]

Hello,
what do I wrong?
I connected the 74HC595N as shown in the diagramm. The original diagramm, I cannot understand.
But in default all relais are on. When i start eg. Relais 1 (S01) than it goes OFF and after the selected time ON again.

[Ray]

Depending on what relay you use: if you use off-the-shelf relay module, sometimes they are ‘active low’, so the logic is reversed.

[Kunstflieger]

Thanks for this answer. This is correct. I use this off-the-shelf relay modul.
Is it possible to change this in the source code on the OSPI?

[Ray]

Each relay has two contact pins, one is normally open (NO) one is normally closed (NC). Why not just use the other contact pin, which counteracts the reversed logic.

[Kunstflieger]

Thanks for your help, Ray.
I just decided to use transistors 2n3904 as shown in this picture

[Aquafluxo]

I connected a 74HC595N to a raspberry pi and I had the same problem, by default all relais are on. To solve the problem
I edit OpenSprinkler.cpp on the OpenSprinkler-firmware directory and in the function “OpenSprinkler::apply_all_station_bits()” at line 1079 add a “~” like this: “digitalWrite(pin_sr_data, (~sbits & ((byte)1<<(7-s))) ? HIGH : LOW );” and recompile the firmware.

[Kunstflieger]

Thanks for this great point! I just have a question. How should I compile it for raspberry pi?
Would it also work if I copy all the content from https://github.com/OpenSprinkler/OpenSprinkler-Firmware to my own github account and change the OpenSprinkler.cpp there?

[Aquafluxo]

I think so, but I gitclone directly to my raspberry pi according to this instructions “https://openthings.freshdesk.com/support/solutions/articles/5000631599-installing-and-updating-the-unified-firmware&#8221;, modify the “OpenSprinkler.cpp” on the “OpenSprinkler-Firmware” directory on the raspberry pi and rebuild with “sudo ./build.sh ospi”

[Author]

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