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r/cyberDeck•
char2

Deciding between ODROID C2 and XU4 for core of a deck

I'm planning out a build, and deciding which SBC to use at the core. I'd like a bit more performance than the Pi3, so I'm currently tossing up between the ODROID C2 and ODROID XU4. I'm also planning to run a Pi Zero W in there as a low-power system, and boot the ODRIOD when I "need" it.

Here's how I see things:

ODROID C2

Pro:

  • UPS addons are readily available: I could run the board from one of these and top it up from a powerbank
  • Can power from micro-USB
  • Fanless
  • 64-bit

Con:

  • Weaker graphics
  • Worse network performance

ODROID XU4

Pro:

  • Better performance
  • USB 3.0
  • Better network performance

Con:

  • 32-bit
  • Needs a barrel connector for power
  • Needs a fan, or a much taller heatsink

Based on the power issues alone, I'm thinking I'll want the C2. Thoughts?

Posted Oct 9, 2017, 8:53 PM UTC

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[deleted]•

[deleted]

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char2OP•

I have decided to go with the C2, for anyone visiting from the future. The USB OTG port will be useful, I think.

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m_bishop•

I was going to recommend that. It sounds like the right decision, since you don't seem to want to drop a huge battery in it.

I have to say, I've never considered having a Pi W as a low-power solution, and then switching to a high-power board for games and stuff. I think that's an awesome idea.

It does make me wonder if it'd be better to really min/max it, though, and have the more powerful board, so long as you're only using it when you really want to do something that requires the extra power.

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char2OP•

Oh hey, I remember you from r/coredump! How's that going?

The power supply I'm planning on using is a Xiaomi Mi 20000mAh powerbank, because it's what I have lying around. (That's 20Ah from 3.7V LiIon cells, so 74Wh, I guess?) Unfortunately, it likes to drop the power output when you plug it in to charge, so I'm going to have to figure out a better way to connect external power so it doesn't reset the whole deck. The classic approach here, AIUI, is to OR the external input together using diodes but then the voltage drop means it'll send 4.3V or so to the board and I'll need to boost it up again. I've been looking at other circuits using ICs and FETs that I don't yet understand.

Having a secondary board that I switch on/off for "serious" work is really important to the concept, because the most important thing for me is the Jank. The idea of going full min-max is interesting, and the XU4 is an intriguing board for that. I have a USB3 SSD which would make a great swap disk for it, and that might make it a good compilation machine for testing ARM stuff. I have a USB-OTG port on the Pi Zero W, so I'll still be able to have fun with gadget mode that way. The problem is power. A quick search suggests that it'll use between 4W and 12W (link, link), which means around 2.4A peak, which is more than the powerbank claims to be able to produce on one port. I could tie the two USB outputs together and protect them, like I need to do with the external power anyway, but it might still be pushing it. The C2's power consumption is between 1.8W and 4W, so I guess it'll be pulling between 0.36A and 0.8A? That seems a bit more manageable, especially if I start adding screens, wifi dongles, a powered hub for the SSD, etc.

I should probably multiply all those numbers by 1.2 to account for any inefficiencies in the power supply as well.

How well do you know your power stuff? This is all new territory to me.

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m_bishop•

Coredump went weird online ... So, I started focusing on more local stuff.

Your power concerns seem reasonable. I feel like you can't make real decisions until you have numbers on the screen, SSD, ect ... That stuff is going to add up and you really don't want to draw too much from a buck converter.

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char2OP•

Yeah a 5" display from hardkernel is 500mA, the spec sheet for the SSD says 700mA, ... even if I can deliver that much current, the powerbank won't do it for long. The other options are to require an external power supply for the big board, or to go to dual powerbanks. I want this thing to be portable so the first isn't appealing, and the second means significantly increased weight, more complex power circuitry and potential problems if I ever want to take it on an aircraft.

I reckon the C2 is the way to go.

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