New to electronics - following kit example for the shift register but caused omega2+ crash/power-cycle
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Hi There,
The forum doesn't seem very active, but throwing this out there just in case...
I am new to electronics and picked up an Omega2+ makers kit to try to learn some basics with an eye towards some home automation eventually. The Omega2+ is super neat and its been fun to play with so far.
I am working through the kit examples with the shift register tutorial at https://docs.onion.io/omega2-maker-kit/starter-kit-using-shift-register.html. All is good with it until I get to the the final wiring instructions that says:
Connecting your Omega to the Shift Register
Connect the GND pin on the Expansion Dock to the Vcc rail.
Connect GPIO1 to SER (pin 14).
Connect GPIO2 to SRCLK (pin 11).
Connect GPIO3 to RCLK (pin 12).
Connect the 3.3V pin on the Expansion Dock to the ground rail.It didn't make a lot of sense to connect GND to Vcc and the 3.3 GPIO to the ground rail. But what do I know? I made the connect and it crashed the Omega2+ (power cycled). All the other wiring looked ok as far as I could tell. So.. I switched the wires (which seemed to make more sense with 3.3V GPUO going to Vcc and ground going to ground) and the Omega2+ doesn't crash, but the code for the shift register has no effect.
Looking for some help guidance on how to approach this:
- Are the original wiring instructions correct (Vcc->ground, GND->3.3V) and I just had something wrong in my wiring that I missed that presumably shorted something? That direction didn't seem to make sense given the circuit diagram in the example which has Vcc going to voltage but am a beginner so not sure if I am reading things correctly.
- Since I powered it in both directions (one of which being wrong by definition) what is the best way to tell if I fried the chip?
- Is there something else I am missing?
Sorry this is so basic and appreciate any advice or direction.
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Hi @chooks,
Are the original wiring instructions correct (Vcc->ground, GND->3.3V)
the original wiring instructions are definitely wrong. In digital electronics, the ground and Vcc are never swapped. It seems to be a copy/paste accident in that final wiring instruction (ping @Lazar-Demin, I guess that's a typo worth correcting quickly). Everything else above looks correct.
The photo also seems to be correct, hard to really definitely tell but it seems I see the black GND wire go to the blue rail and the red one to the red rail on the breadboard.
Since I powered it in both directions (one of which being wrong by definition) what is the best way to tell if I fried the chip?
Probably the chip is fried (otherwise the setup should work).
Does the Omega start when the breadboard is connected the correct way (Vcc->Vcc, GND->GND)? Only the LEDs not working?
- If not, then the chip is definitely fried (draws too much power and probably gets hot)
- If Omega does startup, it's hard to tell because there are all sorts of semi-fried states the chip can have now - but most likely not working 100% ok any more.
If you have an easy means to get a replacement (~$1), I would continue with a known-good new chip to see if it works then.
PS: if you eye some home automation eventually, you might want to look at this
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@luz Thanks for the info and quick response. The Omega starts up when things are wired correctly, but makes sense to just get another chip.
Thanks for the automation link. I'll definitely flash one of my Omega2+ to check it out. Right now just trying to get a sense of what is out there with Home Assistant, Zigbee, ESP32/ESPHome, etc...
Thanks again - appreciate the help!
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@luz Just as follow-up - new chip and correct wiring and everything works fine.
Not sure if anyone is interested, but I am re-working these examples in OpenWRT 23.05 using a current python gpio library. Happy to upload or pass on if there is any desire to update the code examples.
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The instructions were indeed wrong, just pushed a fix!
@chooks very cool! Is the updated version available on github?
