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10 Articles

Ubiquitous Successful Bus: Version 2

October 17, 2024 by 52 Comments

I’ve talked a fair bit about USB-C before, explaining how it all works, from many different angles. That said, USB-C is just the physical connector standard, plus the PD part that takes care of voltages and altmodes – things like data transfer are still delegated to the two interfaces you invariably end up using on USB-C ports, USB 2, and USB 3.

You might think USB 2 and USB 3 are tightly related, but in many crucial ways, they couldn’t be more different. I have experience working with both, and, as you might guess, I want to share it all with you. You might be surprised to hear there’s plenty to learn about USB 2 in particular – after all, we’ve had it hang around for 30 years now. Well, let’s make sure you’re fully caught up!

The Ingredients

USB 2 is a point-to-point link – one side is “host” and another is “device”, with the host typically being a PC chipset or a single-board computer. USB 2 relies on a single pseudodifferential pair. It’s “pseudodifferential” because the wires don’t just do differential signaling – they also use digital logic levels and pullup/pulldown resistors to signal device presence, especially in the beginning when the USB link is still getting established. Indeed, you can imitate a USB device’s presence with just a resistor.
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Need High-Power Li-Ion Charging? How About 100 W

October 4, 2024 by 21 Comments

Ever want a seriously powerful PCB for charging a Li-Ion pack? Whatever you want it for, [Redherring32] has got it — it’s a board bearing the TPS25750D and BQ25713 chips, that lets you push up to 100 W into your 1S Li-Ion pack through the magic of USB Power Delivery (USB-PD).

Why do you need so much power? Well, when you put together a large amount of Li-Ion cells, this is how you charge it all at once – an average laptop might charge the internal battery at 30 W, and it’s not uncommon for laptop batteries to be dwarfed by hackers’-built packs.

A 4-layer creation peppered with vias, this board’s a hefty one — it’s not often that you see a Li-Ion charger designed to push as much current as possible into a cell, and the chips are smart enough for that. As far as the onboard chips’ capabilities go, the board could handle pack configurations from 1S to 4S, and even act as a USB-PD source — check the IC configuration before you expect to use it for any specific purpose.

Want a simpler charger, even if it’s less powerful? Remember, you can use PPS-capable PD chargers for topping up Li-Ion packs, with barely any extra hardware required.

HP WebOS TouchPad Gets With The USB-C Times

October 1, 2024 by 9 Comments

Despite HP shuttering their WebOS project some time ago, the operating system has kept a dedicated following. One device in particular, the HP TouchPad, was released just a month before webOS went under and is still a favorite among hackers — giving the device the kind of love that HP never could. [Alan Morford] from the pivotCE blog shares the kind of hack that helps this device exist in a modern-day world: a USB-C upgrade for charging and data transfer.

The inline micro USB port used is a perfect fit for a USB-C upgrade, with only small amounts of PCB and case cutting required. Just make sure to get a breakout that has the appropriate 5.1 K resistors onboard, and follow [Alan]’s tutorial closely. He shows all the points you need to tap to let your TouchPad charge and transfer data to your computer, whether for firmware flashing or for daily use.

This hack doesn’t preserve the USB-OTG feature, but that’s fixable with a single WUSB3801. Apart from that, this mod is perfect for keeping your webOS tablet alive and kicking in today’s increasingly USB-C dominated world. Once you’ve done it, you might want to take care of your PlayStation 4 controllers and Arduino Uno boards, too.

Design Review: USB-C PD Input For Yaesu FRG7700

May 23, 2024 by 21 Comments

Today is another board from a friend, [treble], who wants to convert a Yaesu FRG7700 radio to USB-C PD power. It’s yet another review that I’ve done privately, and then realized I’ve made more than enough changes to it, to the point that others could learn from this review quite a bit. With our hacker’s consent, I’m now sharing these things with you all, so that we can improve our boards further and further.