Use A Mini PCI-e 3G Card With USB Instead

Back the late 2000s, when netbooks were the latest craze, some models would come with an inbuilt 3G modem for Internet access. At the time, proper mobile Internet was a hip cool thing too — miles ahead of the false prophet known as WAP. These modems would often slot into a Mini PCI-e slot in the netbook motherboard. [delokaver] figured out how to use these 3G cards over USB instead.

It’s actually a fairly straightforward hack. The Mini PCI-e standard has a couple of pins dedicated to USB data lines, which the modem in question uses for communicating with the host computer. Unfortunately it’s not quite as simple as just soldering on a four-wire USB cable. The modem relies on the 3.3V power from the Mini PCI-e slot instead of the 5V from USB. No problem, just get a low-dropout 3.3V regulator and run that off the USB port. Then, it’s a simple enough matter of figuring out which pins are used to talk to the SIM card, and soldering them up to a SIM adapter, or directly to the card itself if you’re so inclined. The guide covers a single model of 3G modem but it’s likely the vast majority of these use a very similar setup, so don’t be afraid to have a go yourself.

Overall Mini PCI-e is a fairly unloved interface, but we’ve seen the reverse of this hack before, a Mini PCI-e to USB adapter used to add a 12-axis sensor to a laptop.

[Thanks to Itay for the tip!]

16 thoughts on “Use A Mini PCI-e 3G Card With USB Instead

  1. Hi,

    there is a pretty cool piece of (open) hardware available that you can use for that without the need for soldering wires to the card, done by Harald Welte.
    Blog post:
    Blog post with update:
    Wiki entry:
    Shop for assembled breakout board:

  2. Or buy one of these:

    I had 3 mini PCIe modems attached to a powered USB hub, hooked up to a Pi running Java SMSLib and PIRCBotX as a bridge between IRC and USSD/SMS. Channel members could view incoming USSD messages, or SMS’s, and respond to them, or initiate either. It worked pretty well!

  3. If you have a laptop with a Turbo Cache or Turbo Memory slot, it will take a Mini PCIe to USB 2.0 adapter. Pop in a large capacity USB stick and you have additional internal storage. I used a 64 gig with a metal housing that’s just the metal surround of the plug extended to cover the whole thing. I also carefully clipped off and ground down the points where the USB connector is soldered to the PCB, just to ensure they would not short to anything on the laptop’s board.

    Turbo Cache was a failure for its intended purpose, a faster form of ReadyBoost. It could be reconfigured as simply some additional storage, but with only a few gigs of space, not too useful.

    Now Intel is trying the same trick again, this time with a new type of non-volatile RAM they claim is 1,000 times more durable and 1,000 times faster than what’s used in SSD’s, nearly as fast as main system DRAM. It’s also available in (IIRC) 32gig and 64gig capacities. Reviewers have their hands on it now. the modules and desktop motherboards with slots for it should ship soon. One test I saw showed it cutting Windows 10 boot time by nearly half, and also speeding up launching of various games and office software – the second time around. The first time it cached stuff so it’d be ready to load from the cache instead of main storage.

    Supposedly it can also be configured as a 4th level CPU cache so you’d have huge chunks of your OS and software loading from this fast crosspoint NVRAM to system RAM instead of a hard drive or SSD. Since it’s non-volatile, a power failure or crash likely would not lose pending writes to storage.

    In other words, it’s Turbo Cache that actually makes a computer faster. Turbo Cache was a neat idea but by the time OEMs got around to using it, laptop CPUs had become faster, there was DDR2 and laptops were loading up to 4 gigs of it. A 4 gig cache on a x1 PCI Express lane wasn’t fast enough to do any good. Dell took Turbo Cache, redesigned it to use a proprietary connector and made modules up to 16 gig (which go really cheap on eBay due to only working with certain old Dell laptops) but there’s still the too much slower than DDR2 problem.

    There’s something to hack – make a Dell Turbo Cache module useful.

    1. Interesting, got a T400 with both a turbo cache and a 3G modem mini PCIe format slot empty and wanting some purpose in life.

      Shame nobody did a SSD to work in the turbo cache hole.

      Also have an Apsire One with a spare hole, but only thing I hear of working in them is a video decoder accelerator.

  4. “miles ahead of the false prophet known as WAP” … In my country, orange offered wap unlimited for 3 USD. Combine that with “your freedom” software or 2 other that i cannot think right now and you had cheap INTERNET… those were the days:D

    1. I think there was a period of 2 years where a deal was gettable in North America, with unlimited WAP tied to a specific device like a Palm or something. early noughties.

      1. companies like Ricochet offered such a thing. Downside was extremely limited coverage. Even its home town of San Jose was patchwork, and outside of a few large cities (and you could forget about the interstate between them) they were completely nonfunctional.

        In true Silicon Valley Skeeviness, Ricochet had its people pushing the devices and sales plans in stores like Fry’s Electronics less than a week before declaring they were going out of business and shutting down the network.

        bad times.

  5. Not all that surprising, the Mini-PCIe specification does include a USB port as part of the standard connector… I’ve had several motherboards with mPCIe slots on them with some not even having PCIe signals, rather only had the USB interface. And then I had a large number cards that would fit into those slots, many only had a USB interface (WiFi, WWAN, Serial/parallel port card, and numerous other cards that don’t push a lot of bits around).

    I have a small pile of 4G modems that actual use both interfaces. The USB port is used for hosting a small Read-only flash chip containing the device’s drivers. The PCIe interface is connected to the modem half of the device (and only comes on when magic incantation are spoken to the USB side by the provided driver).

    1. Are you sure about this? Most 4G modems are USB only, and change personalities from Mass Storage to CDC or ACM when the magic incantation occurs. No PCIe involved at all, though.

  6. I use these cards for IoFAT – Internet of Far Away Things! ie solar powered remote data acquisition.

    They have USB but that’s a pain to interface to your favorite micro-controller. As well as USB many of them have TTL serial which is perfect for interfacing to you uC (normally pins 49, 51).

    I just make breakout boards for prototyping. mini PCI-e (M1 because the newer standard is called M2) has 0.8mm pin pitch so it’s not so hard to solder the connector onto the PCB. The M2 sockets would be a challenge as they look to be about 0.4mm to 0.5mm.

  7. Can someone figure out how to add USB to those RTL 8191SE cards I keep finding in dead netbooks please?

    If it does indeed have USB on there it should be possible to kludge these into USB network adaptors, using the harvested antennas from some other device.

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