I imagine any hardware that is running an OS is going to take more time to power up that you need.
If the Omega had a sleep mode that'd be the way to do it but as yet, that's not an option.
What is the reason you need such quick power up? Is there some other way to tackle the requirement?
Cheers,
Chris.
The 'Magic Smoke' is what makes it work! If you let that out, no workee end of story 
@crispyoz
It's tricky to find any data on the current sourcing capability of the GPIO pins. I only had a quick look in the Onion docs and the Mediatek datasheet without success.
You're drawing ~15mA from the port with the arrangement you describe assuming the 1.8V LED drop per @Neil-Manuel's reply. Once you find the maximum current source rating on the GPIO pin you can make a call.
It's also worth checking the sink current rating vs the source current as sometimes the sink current is the greater amount. In this case, you reverse the LED(s) direction, attach the resistor(s) to +Ve and switch the GPIO off to activate it.
HTH.
@Lazar-Demin
Thanks, I see the download buttons for the Omega2-LTE and DASH but the in the case of the Pro it's as I described earlier.
Downloading the repo works.
@Lazar-Demin, just for interest - what's the correct way to download the DXF?
Can it be done using a browser? When I attempted this (right-click "save link as") a DXF file is saved but it's structure is XML and appears to be related to the HTML page on which the DXF file link is presented. Here's the top dozen lines of the 'DXF' for the Omega-Pro:
<!DOCTYPE html>
<html lang="en" >
<head>
<meta charset="utf-8">
<link rel="dns-prefetch" href="https://github.githubassets.com">
<link rel="dns-prefetch" href="https://avatars.githubusercontent.com">
<link rel="dns-prefetch" href="https://github-cloud.s3.amazonaws.com">
<link rel="dns-prefetch" href="https://user-images.githubusercontent.com/">
<link crossorigin="anonymous" media="all" integrity="sha512-OZSLZxbfZRavuNMaKn9S2z6nOiqb+cSXqL/eTi4TqwhiRm1fDxQpuwjViN7NzGw/nhXT4O0BZIIg0Ym7szrbpg==" rel="stylesheet" href="https://github.githubassets.com/assets/frameworks-39948b6716df6516afb8d31a2a7f52db.css" />
<link crossorigin="anonymous" media="all" integrity="sha512-jaRxAk/R7Eq6XXtxt2dWYc6UfgT/Jk9zYWYh4UpAt5LFRnYVaWqEM3sPhUFL3fOBmHhHoOcn4wfLkMS21Q1yaw==" rel="stylesheet" href="https://github.githubassets.com/assets/site-8da471024fd1ec4aba5d7b71b7675661.css" />
<link crossorigin="anonymous" media="all" integrity="sha512-9nE+XgrWtARaS0zwxOiHy2GiHph7zd3w1/JhlkltB0BJKwNHjq0jmjMcOptBcoiHSmpEIeevcNvzeXoHqK77eA==" rel="stylesheet" href="https://github.githubassets.com/assets/behaviors-f6713e5e0ad6b4045a4b4cf0c4e887cb.css" />
etc.
Clicking on the DXF file link directly opens it's content in GitHub - I guess this can be copy-pasted to a local file but that's inconvenient.
I'm using MS Edge FWIW
I imagine any hardware that is running an OS is going to take more time to power up that you need.
If the Omega had a sleep mode that'd be the way to do it but as yet, that's not an option.
What is the reason you need such quick power up? Is there some other way to tackle the requirement?
Cheers,
Chris.
@dbell You need a USB A to Micro-USB (or in millennial language a "Android Charger") cable. When plugged into to PC it should appear as additional COM port in device manager. If not then your cable might truly be a charge-only cable with no data connections, or there's a fault with the dock.
The only physical UART (serial) connections are on the dock expansion connector. Additionally you'll need voltage level translator/interface circuitry before you can connect this tot he PC serial port (which will use RS232 levels).
The 'Magic Smoke' is what makes it work! If you let that out, no workee end of story
@Crazi-Tane
From memory: when you connect via USB the computer should register the onion as a serial port.
Just use the ssh as you would over a serial connection (? not familiar with the MAC way of doing this sorry).
HTH
@György-Farkas , yes I've recently updated to b227 with the oupgrade -l -f command.
Next question, is there a list of release notes for the 0.3.2 branch & if so, is it accessible?
Thanks, I'd forgotten about the manual method. That worked fine.