OpenRex – Open Source Hardware Project | Hacker News Reader

OpenRex – Open Source Hardware Project

imx6rex.com

Great work on this, it looks like a great project. Right up my street with open source. For me personally the price vs specs [1] just don't make this viable, considering you can get a Rockchip board for half [2] the price and with better specs. It's also pretty open source [3] too.

I'm really excited for the iMX8 though. It looks like it has much better specs, and if they can remain as open source and hobby friendly as the iMX6 then I'm all for it, even if it costs slightly more.

1. https://www.voipac.com/#category1

2. https://www.pine64.org/?product=rockpro64-4gb-single-board-c...

3. https://github.com/rockchip-linux

I wish more OSHW boards featuring the imx6 gained momentum. It's a lovely processor to work with, and NXP's documentation puts most vendors' manuals to shame.

Plus, if you ever ship at scale, it's pretty easy to get your hands on a large quantity of them!

I've been developing on i.MX6 for the past 6-7 years and it's been the easiest Linux processor to work with out of the lot (looking at you, Renesas!)

And there's no shame with using a processor/RAM/eMMC combo on a SOM, either. Doing the high speed DDR layout on 6 or 8 layers of PCB is not a task for novices. Saving the low-speed interface work for a larger 2-layer carrier PCB makes the project go really smoothly (just watch the EMI off those right angle card-edge connectors!)

There are plenty of companies selling the IMX in all kinds of configurations for really decent volume prices. TechNexion and Boundary have been my favorites so far.

I concur. i.MX6 not the fastest nor least expensive nor most power efficient SoC but the documentation and wide variety of SOMs make it competitive for lots of products.

I've designed it in a thermal imaging product, where it's 20 bit wide DVP support came in very handy.

I remember having a lot of problems with their Android BSP for it. It came along with some pretty questionable patches to the framework, but I never had any issues with the actual Linux kernel.

It was Freescale. NXP has been trying to make their docs harder to get. I was in the process of writing a BSP for their Sabre boards during the acquisition, and they went as far as deleting previously free resources off their site and asking me to pay for a support contract to get them back.

NXP's stance is probably what made others shy away from the chips.

That hasn't been my experience with NXP, but that's a bummer.

Yeah, mine either. I will say that NXP did a fair job of screwing up Freescale's web resources, though.

That, I agree with. It's also annoying that many of the resources that used to be freely available (datasheet, reference manual, other docs) now require a login to download.

Minor hassle, however.

Why not Beaglebone Black/Green/Blue? This is a real question.

TI's stuff is open. TI's manuals are awesome. It already exists. There are user iterations that are different from the TI reference. The board is a much cheaper 6 layer board.

What niche does this serve that a Beaglebone would not?

I use iMX6 because it has nice features for image processing, like compressing camera input to H264 before putting information to memory.

I have worked with TI boards in the past and agree they have great documentation also. One pitfall I did run into however was that the development boards are sold at a very low price but when you get into production quantities, I found the prices were higher. Sort of a loss leader business model. But yes if you want something to hack around with and are looking for great documentation and tool chains TI is definitely worth considering.

We’re using a derivative of this, the TinyRex SOM, in MNT Reform (libre laptop).

I only wish the mating connectors had an alignment pins, those are a pain to solder accurately when placed manually.

Oh man, very true.

I'm a happy Fedevel customer. Robert does a great job putting together the material. I haven't finished the course I bought, but I've gotten a lot out of what I've gotten through so far. Definitely helped me "level up" on my PCB design skills.

Some of the PCB layer diagrams look pretty cool: https://www.imx6rex.com/wp-content/uploads/2016/02/OpenRex-L...

Anyone know why they are designed this way? Very wiggly traces.

Typically those wiggles are for length matching on parallel busses. Since the signals are clocked at a high speed, ensuring all the bits arrive at the same time is crucial.

Not just parallel buses. You can see several differential pairs as well, which look a lot like the parallel buses except the pairs are routed much closer together.

Differential pairs carry polar opposite signals so that any noise can be canceled out by comparing the two. While parallel bus traces need to be routed to 1/20-1/40th of a wavelength, the differential pairs need to be routed to within 20mils of each other with impedance controlled traces (which depends on distance to each other and other traces as well as material variability, hence the tight routing).

All other considerations aside IMO the Rex board is aesthetically a beautiful board. For me that was enough to overcome the sticker shock.

Is anyone aware of a similar open-source hardware project around camera sensors image processing?

I'm a bit confused with why the prices in the Web store are so high. Is it the fact that it is open source driving the price up? Or is the Slovak manufacturer just faced with high manufacturing costs? Would getting seed studio's fusion pcb service to manufacture drive the prices down? Or Would getting China to manufacture this be considered immoral some how?

The prices seem fairly in line with what you normally see for fully open source boards. They cost a lot because of the low volume and huge amounts of work that have to be done. For a regular board you just slap down whatever parts you want but if it has to be open source you need to put in a lot more work looking for parts with free firmware and spec sheets as well as writing a lot of firmware yourself.

The GnuBee is an open source nas that is actually cheaper than everything else on the market. I suspect because its a fairly simple device and the proprietary versions are super marked up as well as the creator being located inside Shenzhen

200 euro? That's gonna be a no from me, dawg.

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