Relais are inverse | OpenSprinkler

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This topic has 7 replies, 3 voices, and was last updated 7 years ago by Aquafluxo.

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August 2, 2019 at 4:34 pm #61992

Kunstflieger
Participant

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.

August 3, 2019 at 9:28 am #62001

Ray
Keymaster

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

August 3, 2019 at 1:55 pm #62005

Kunstflieger
Participant

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?

August 3, 2019 at 4:16 pm #62011

Ray
Keymaster

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.

August 13, 2019 at 1:27 am #62125

Kunstflieger
Participant

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

August 19, 2019 at 6:45 pm #62222

Aquafluxo
Participant

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.

August 21, 2019 at 1:55 pm #62257

Kunstflieger
Participant

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?

August 22, 2019 at 12:07 pm #62283

Aquafluxo
Participant

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”, modify the “OpenSprinkler.cpp” on the “OpenSprinkler-Firmware” directory on the raspberry pi and rebuild with “sudo ./build.sh ospi”
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