More searching also turned up a fairly healthy OpenWRT Community based on the RT5350 chipset. For those who don’t know, OpenWRT is a free, open-source Linux distribution targeted at routers. It’s likely that you’ve heard of users putting Linux on their router, but you may have brushed it off.. This is reasonable, since for the most part you plug one in and let it sit on the desk – how exciting is that? All it’s gotta do is take data from here and put it there.
Now consider it from another side: This little tiny PCB module can act as a router, AND it could be running Linux in addition to doing that. That means that the wealth of Linux programs, and certainly all the stuff you can write yourself, can run standalone on this little widget WHILE it serves wifi. Basically, your 11 bucks is buying a teensy little computer, complete with USB, WiFi, LAN, and all the miscellanous ports we saw that fits in about 3 square inches of space. Now that’s cool.
The OpenWRT community for RT5350 is centered around the patches maintained by Squonk. He seems to be the developer who originally ported OpenWRT to the RT5350, using a clone of the HAME MPR-A1 portable hotspot called the MPR-L8. Who manufactures it? Still no clue, but it usually runs a few bucks cheaper than the MPR-A1.
Digging in to the development on those devices showed that they may be an even BETTER choice for a widget to hack on: In addition to RT5350, this thing comes with USB and LAN ports and is powered by an 1800mAh Li-Ion battery – all in a fairly compact dongle form factor. It can even use it’s battery to provide USB charging to your cell phone – cool!
The original purpose of the MPR-A1 is to act as a 3G wifi hotspot: Buy a USB 3G modem and a data plan, and you can use the MPR to serve wifi to a couple of pals out at a coffee shop or park. It’s portable, self-powered (and rechargable), and contains the essentials for all sorts of interesting wireless hackery.
Gotta have it? Yep, same here. You can buy the original HAME MPR-A1 from places like Amazon for about 20 bucks, or you can get a clone called MPR-L8 from places like AliExpress for a bit less. The MPR-L8 seems to be a copy of the MPR-A1 v1.4, whereas the genuine MPR-A1 available these days are v2.1 or more. For the most part, they seem interchangeable and both almost carbon copies of the PDF: Generic Ralink Demo Schematic For RT5350. Plenty of useful knowledge of how the system goes together in there! Searching the web for the datasheets and system schematics will turn up tons of other stuff as well.
Without further ado, let’s introduce the pile of devices presently on the testbench.
Fig 1 – A Bunch of RT5350-based Devices
So you got your HLK-RM04′s and the development kit there on the left, and a handful of MPR-L8′s there on the right in various stages of disassembly. We’ll first take a peek at the RM04, then dive into the MPR-L8.