Hacker News Reader

Comment by creshal | Hacker News Reader

There's no ethernet port. So, also an ethernet adapter. But there's only one USB port (µUSB, too, so you most likely need an adapter to regular USB). So if you want more than just ethernet, you'll need an USB hub. But the RasPi's power supply has always been weak, so better get an actively powered one…

And soon you're paying four times as much for the accessories than for the RasPi.

View on HN

This is an awesome board for embedded development. Not as powerful or I/O rich as the Beaglebone Black, but add $6 worth of CAN transceiver chips and a 12V->5V switching power supply and you've got an incredibly powerful automotive compute unit. The Pi 1 was a bit underpowered for what I'm doing, and this might hit the sweet spot while dropping $35 off my unit cost for small quantities. None of the issues you mention affect that calculation at all.

Who uses ethernet anymore?

That's exactly what I'm going to use this for, too. Right now I have an original Pi B logging GPS and OBD data, but it's crammed into a small storage spot in the car and is a big waste of space. I'm super excited to be able to cut my project to less than half its original size. I don't need ethernet (other than for debugging), four usb ports, etc. etc. I think this is going to be fantastic for creating homemade embedded devices.

Do you have or did you follow a write up for this? I know I would be interested in reading how you set that up!

I don't right now, unfortunately, but a writeup is next on my list of projects after the carputer is complete. I'll post it here if there's interest. For learning about the OBD protocol, though, these resources have been very helpful:

The ELM 327 data sheet (this is the chip in most OBD devices you'll find on amazon): http://elmelectronics.com/DSheets/ELM327DS.pdf

Wikipedia's article on OBD PIDs: https://en.wikipedia.org/wiki/OBD-II_PIDs

"A complete guide to hacking your vehicle bus on the cheap & easy": https://theksmith.com/software/hack-vehicle-bus-cheap-easy-p...

There's a PyOBD python module out there (my carputer is built in python), but it's a fairly simple process so I just rolled by own using pyserial.

How exactly has the power supply been weak? I've been running three PIs (A+, B and B+) for a few years with no problems with just simple cell phone power adapters. However, I'm not plugging any extra hardware into them...perhaps that's why I haven't run into problems?

Yes, the parent was talking about lacking power through the Pi's USB ports thus often requiring a powered USB hub.

My issue is with the Pi's use of micro USB for power, I'd rather it use a barrel connector, it's not like it doesn't have the space. Yes, I know the choice is based on the presumption that everyone already has a micro USB power adapter from a cell phone. The use of micro USB for power on this Pi Zero makes a lot more sense given the form factor.

> However, I'm not plugging any extra hardware into them...perhaps that's why I haven't run into problems?

Yes. Phone chargers provide plenty of power for the Pi itself, but once you add several USB devices like wifi/ethernet you'll need beefy ones.

But even that is normally not much of a problem, because (especially on the B+) each device has their own port. If you plug several into a hub, however, you'll quickly exceed the hub port's power rating. Hence the need for an active hub.

USB-OTG cables with power supply exist.

Ethernet USB adapters tend to be very flakey. (At least that's my opinion/experience.)

It was my understanding that the ethernet on the Raspberry Pi sat on the USB anyway.

Reply on news.ycombinator.com