Do you have a 5 V device you want to run 24/7, no matter whether you have electricity? Not to worry – Linear Technology has made a perfect IC for you, the LTC4040; with the perfect assortment of features, except perhaps for the hefty price tag.
[Lukilukeskywalker] has shared a PCB for us to review – a LTC4040-based stamp you can drop onto your PCB whenever you want a LTC4040 design. It’s a really nice module to see designed – things like LiFePO4 support make this IC a perfect solution for many hacker usecases. For instance, are you designing a custom Pi HAT? Drop this module to give your HAT the UPS capability for barely any PCB effort. if your Pi or any other single-board computer needs just a little bit of custom sauce, this module spices it up alright!
We would not be surprised if DSI screens made up the majority of screens on our planet at this moment in time. If you own a smartphone, there’s a 99.9% chance its screen is DSI. Tablets are likely to use DSI too, unless it’s eDP instead, and a smartwatch of yours definitely will. In a way, DSI displays are inescapable.
This is for a good reason. The DSI interface is a mainstay in SoCs and mobile CPUs worth their salt, it allows for higher speeds and thus higher resolutions than SPI ever could achieve, comparably few pins, an ability to send commands to the display’s controller unlike LVDS or eDP, and staying low power while doing all of it.
There’s money and power in hacking on DSI – an ability to equip your devices with screens that can’t be reused otherwise, building cooler and cooler stuff, tapping into sources of cheap phone displays. What’s more, it’s a comparably underexplored field, too. Let’s waste no time, then!
Decently Similar Internals
DSI is an interface defined by the MIPI Alliance, a group whose standards are not entirely open. Still, nothing is truly new under the sun, and DSI shares a lot of concepts with interfaces we’re used to. For a start, if you remember DisplayPort internals, there are similarities. When it comes to data lanes, DSI can have one, two or four lanes of a high-speed data stream; smaller displays can subsist with a single-lane, while very high resolution displays will want all four. This is where the similarities end. There’s no AUX to talk to the display controller, though – instead, the data lanes switch between two modes.
Last time, we went over switching regulator basics – why they’re wonderful, how do you find a switching regulator chip for your purpose, and how to easily pick an inductor for one. Your datasheet should also tell you about layout requirements. However, it might not, or you might want to deviate from them – let’s go more in-depth on what those requirements are about.
Appreciate The Feedback
The two resistors on the right decide what your output voltage will be, and their output is noise-sensitive
There’s a few different switching regulator topologies. Depending on your regulator’s topology and how many components your chip contains, you might need some external components – maybe a Schottky diode, maybe a FET, or maybe even a FET pair. It’s often that the FET is built-in, and same goes for diodes, but with higher-current regulator (2 A to 3 A and above), it’s not uncommon to require an external one. For sizing up those, you’ll want to refer to the datasheet or existing boards.
Another thing is input and output capacitors – don’t skimp on those, because some regulators are seriously sensitive to the amount of capacitance they’re operating with. Furthermore, if you fail to consider things like capacitance dropping with voltage, you might make your regulator very unhappy – not that a linear regulator would be happy either, to be clear. We’ve covered an explainer on this recently – do check it out!
One thing you will likely need, is a feedback resistor divider – unless your switching regulator is pre-set for a certain voltage or is digitally controlled, you need to somehow point it to the right voltage, in an analog way. Quite a few switching regulators are set for a certain voltage output, but most of them aren’t, and they will want you to add a resistor divider to know what to output. There’s usually a formula for resistor divider calculation, so, pick a common resistor value, put it in as one of the resistors into the formula, get the other resistor value out of that formula, and see what’s the closest value you can actually buy. Don’t go below about 10 kΩ so that you don’t have unnecessary idle power consumption, but also don’t go too far above 100 kΩ to ensure good stability of the circuit. Continue reading “Switching Regulator Layout For Dummies”→
Recently, the Ukrainian government has published a database of Western components being used in recently produced Russian armaments, and it’s a fascinating scroll. Just how much does Russia rely on Western manufacturers’ parts? It turns out, a surprising amount. For instance, if you are wondering which ICs are used to build Iran-produced Shahed drones, it seems that it’s a wholebunch of Texas Instruments parts, as well as some Maxim, Intel, and Xilinx ones. Many of the parts in the lists are MCUs and FPGAs, but it’s also surprising how many of the components are jelly bean parts with multiple suppliers.
There appear to be thousandsofpartslistings, compiled from a good few dozen pieces of equipment that volunteers appear to have taken apart and scrupulously documented – just take a look at the dropdowns at the top of the page. The Ukrainian government is advocating for parts restrictions to be implemented based upon this data – as we all remember, it’s way harder to produce hardware when you can’t buy crucial ICs.
Even for a regular hacker, this database is worth a scroll, if only to marvel at all the regular parts we wouldn’t quite associate with military use. Now, all that’s left is to see whether any of the specific chips pictured have been sold to washing machine manufacturers.
[sdz] of Vogons forum brings us an unexpected device for the 21st century – a 3dfx Voodoo 4 card in MXM format, equipped with 64MB of RAM. This isn’t just a showpiece – this card actually, properly works when installed into our hacker’s Dell Precision M4800, and [sdz] tells us more on how the card came to be.
Equipped with a VSA-100 GPU, this card has a whole lot of support components for adapting old interfaces to modern ones. There’s a PCIe-PCI bridge IC, an FPGA, HDMI muxes, and a Realtek scaler for video conversion. Handling all the MXM interfaces would’ve been downright impossible, so the card also holds an LVDS header for the M4800’s panel. Plus, for testing all of it, [sdz] has developed a PCIe to MXM adapter board with minimal circuitry needed to have the card work – this is a seriously involved hack and it’s executed remarkably well.
The forum post shows a whole lot of the journey, from receiving the PCBs to code and FPGA gateware bringup, as well as videos of VGA and HDMI operation. In the end, our hacker shows us a fully working setup, the 3dfx card inserted into M4800 and driving its display, as well as overclocking experiments; the author has promised to open-source the card files in due time, too. It’s seriously nice to see DIY MXM cards in the wild, and if you ever wanted to build one, we’ve got an article tells you everything you could want to know about the MXM standard.
You know the feeling of having just created a perfect setup for your hacker lab? Sometimes, there’s just this missing piece in the puzzle that requires you to do a small hack, and those are the most tempting. [maxime borges] has such a perfect setup that involves a HDMI 4:2 switch, and he brings us a write-up on integrating that HDMI switch into Home Assistant through emulating an infrared receiver’s signals.
The HDMI switch is equipped with an infrared sensor as the only means of controlling it, so naturally, that was the path chosen for interfacing the ESP32 put inside the switch. Fortunately, Home Assistant provides the means to both receive and output IR signals, so after capturing all the codes produced by the IR remote, parsing their meaning, then turning them into a Home Assistant configuration, [maxime] got HDMI input switching to happen from the comfort of his phone.
We get the Home Assistant config snippets right there in the blog post — if you’ve been looking for a HDMI switch for your hacker lair, now you have one model to look out for in particular. Of course, you could roll your own HDMI switch, and if you’re looking for references, we’ve covered a good few hacks doing that as part of building a KVM.
I don’t like HDMI. Despite it being a pretty popular interface, I find crucial parts of it to be alien to what hackers stand for. The way I see it, it manages to be proprietary while bringing a lot of the old cruft in. It doesn’t have a native alternative like DisplayPort, so portable implementations tend to suffer power-wise; the connector situation is interesting, and the HDMI Foundation has been doing some weird stuff; in particular, they are pretty hostile to open-source technology.
This article is not the place for such feelings, however, especially since I’ve expressed them enough in the DisplayPort article. We the hackers deserve to be able to handle the interfaces we stumble upon, and I firmly believe in that way more than in my right to animosity towards HDMI.
The HDMI interface is seriously prominent wherever you look, in part because it’s the interface created by the multimedia-involved companies for the multimedia-involved companies. Over the years we’ve had it, it’s been more than sufficient for basically everything we do video-wise, save for the highest resolutions.
It’s also reasonably simple to wire up, hack on, and even bitbang. Let’s go through what makes it tick.
The Core
HDMI is, at its core, three differential pairs for data, plus one pair to clock them and in the darkness bind them. It’s a digital interface, though it is a fun one. This makes it way more suitable for higher-distance video transmissions than interfaces like VGA, and as long as you stick to relatively low resolutions, HDMI won’t have as many asks in terms of PCB layout as DisplayPort might, thanks to HDMI link speeds scaling proportionally with the display resolution.
