Odroid-N2 16 Channel relay not triggering

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symbytech
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Odroid-N2 16 Channel relay not triggering

Unread post by symbytech » Tue Mar 17, 2020 10:49 pm

I added a 16 channel relay PCB to my Odroid-N2 and it worked. Both Odroid-N2 and relay failed (seemingly unrelated) and were replaced with new units. All the rest remained the same. The relays don't trigger now.

I'm not able to find what the actual level logic of the Odroid-N2 is. Some suggest the logic level can be either 3.3Vdc or 5Vdc subject to configuration, not sure about this. Perhaps the logic of the relay is not compatible? I measured the GPIO pin and am got 3.3Vdc across pin and GND. I've not measured all the GPIO pins that control the relays. I believe the optoisolator needs 5Vdc however I'm lead to believe it gets the 5Vdc from the relay PCB supply. Both the original and replacement relay PCB use the same optoisolators and 8CH Darlington Sink Drivers (attached the datasheets). The relays (Tongling 5Vdc JQC-3FF-S-Z and Songle SRD-05VDC-SL-C) on both PCBs are triggered by 5Vdc however I'm lead to believe this too comes from the relay PCBs power supply and not the level logic. The original relay was a 12Vdc supply that appeared to get the 5Vdc from the regulator. The replacement has a 5Vdc supply without a regulator.
Attachments
LM2596.pdf
(4.96 MiB) Downloaded 8 times
Original 16Ch Relay PCB.jpg
Original 16Ch Relay PCB.jpg (451.68 KiB) Viewed 507 times
Toshiba ULN2803APG Datasheet.pdf
(457.07 KiB) Downloaded 12 times
PC8X7C Optoisolator.pdf
(144.26 KiB) Downloaded 5 times

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Re: Odroid-N2 16 Channel relay not triggering

Unread post by odroid » Wed Mar 18, 2020 11:06 am

N2 GPIO output level is 3.3Volt.
You might need several NPN transistors something like this.
viewtopic.php?f=97&t=36823&p=273497#p273497

symbytech
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Re: Odroid-N2 16 Channel relay not triggering

Unread post by symbytech » Wed Mar 18, 2020 2:57 pm

I am guessing a level logic convertor would help?

What I don't understand is how the system worked before but doesn't now. The only thing that changed is the Odroid-N2 and the relay board. It doesn't make sense.

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Re: Odroid-N2 16 Channel relay not triggering

Unread post by odroid » Wed Mar 18, 2020 5:47 pm

Do you have a DMM to measure the Opto-isolator input & output voltages?

symbytech
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Re: Odroid-N2 16 Channel relay not triggering

Unread post by symbytech » Wed Mar 18, 2020 7:55 pm

Supply Voltage:

Vcc is 12.2Vdc & 5.2Vdc, I normally like to give a little more to compensate for loads. I'm also testing the relay PCB that was replaced.

When Triggered - Triggered by shorting pins to GND
@ 12Vdc Vcc | 5Vdc Vcc

Across pin 1 & 2 - 1.144Vdc | 1.136Vdc
Across pin 3 & 4 - 0.35Vdc | 0.110Vdc

When Untriggered
@ 12Vdc Vcc | 5Vdc Vcc

Across pin 1 & 2 - 0.030mV | 0.118Vdc
Across pin 3 & 4 - 5.05Vdc | 5.05Vdc

4.57 - 4.66Vdc is measured on each of the header pins that would go to the Odroid-N2, not sure if this is good for the Odroid-N2?

All relays were manually triggered and the voltages applied to the coils measured as 4.27Vdc & 4.3Vdc across the diode & resistor.

Total current draw with all relays triggered:

580ma @ 12.2vdc
1.005 @ 5.05Vdc

Are the Odroid-N2 GPIO 5V TTL tolerant? Would a level logic convertor work?

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Re: Odroid-N2 16 Channel relay not triggering

Unread post by odroid » Thu Mar 19, 2020 9:20 am

Nope! It is not 5V TTL tolerant.
It must be 3.3Volt CMOS. Otherwise, you will damage the SoC.

Consider using a level-shifter board something like this.
https://www.hardkernel.com/shop/level-s ... v-to-3-3v/
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