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Forum Index : Microcontroller and PC projects : Another easy-build one - PZ0
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 8781 |
 This is really a bit of a quick & dirty build for those who like to build stuff and want to play with HDMI and USB without buying a pre-assembled board. It's cheap and cheerful, for the most part. The most expensive components are the Pico 2 and the Adafruit HDMI/DVI breakout board. It's quite possible to build a basic version with only one surface mount device (the full size SD card socket), and even that's optional. The additional bits may involve SMD soldering. A couple of experimental bits. The power is toggled on and off using a little button and a mosfet (circuit found on Big Clive's channel). Option: The USB signals are disconnected using a clicky relay (remember those?) powered by the supply from the updating USB socket. The board can be built using either a full size SD card or a micro SD card and a WII socket. Firmware update connection can be done in one of three ways: 1 - direct connection to the Pico USB. 2 - connection to a mini USB updating socket and the hub disconnected using jumpers 3 - connection to the mini USB socket but with automatic hub disconnection as mentioned above. This should be particularly useful if the board is in an enclosure. I make no apology for using mini USB. It's by far the best small format USB connector for this job, being small, simple, rugged and relatively easy to hand solder. You don't need a breakout board for it. The only audio is a piezo buzzer or magnetic speaker on GP22. I've discovered that I rarely use the audio output. If I want to listen to music then I use headphones on my PC. I can't use speakers anyway. I threw in a GPIO connector for 8 uncommitted GPIO pins and a QWIC connector. Of course, it's smaller than 100x100mm to keep the PCB price down and it fits the RM2015S case. Incidentally, if you can't source that one the RM2015M is sometimes more readily available but it is 50mm high. That may not be a problem. Same fixings inside. I'll complete the design If I decide that I need one or if anyone else would like to build one. It's reached the stage where it needs component numbers, the schematic and BOM but it looks like it will probably work. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3743 |
I'm not sure I fully understand the design, but for hdmi usb, I feel what is needed is at least 4 and maybe 7 USB ports to accommodate Peter's new work. For me, PSRAM is also needed, but that may have to wait until it's available inexpensively on a 40-pin Picomite. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on FOTS |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8781 |
My reasoning about PSRAM was that it's nice to have, and if Raspberry Pi had a module that had it then I'd use it. However they don't. That means that any design using modules rather than the home-unsolderable bare chip is totally dependent on a third party supplier and I want to get away from that if possible. The other modules aren't as important as they are long-established Chinese ones and are unlikely to disappear in the forseeable future. There are 4 USB ports on board (2 on the front and 2 on the back). You could piggy back an external hub from one of those or, if you short out a diode and the Pico can work that way, you also have direct access to the Pico's USB connection via the mini USB socket. As I said, this is basically a cheap quick and dirty. If you have the money to get JLCPCB to assemble better boards then that's fine, but you need to be able to sell or use the extra ones because of the minimum order. I could easily have used one of the RP2350 modules, and I still might, but that wasn't the target this time. It would certainly need a bigger PCB and possibly a bigger case. The modules are more expensive and there is a single manufacturer for each one - none of them as big as Raspberry Pi. There are all sorts of things I *could* have done, but this one is a compromise. Note that it is based on the Pico 2, so any device that is pin compatible and has the HSTX should work, even if it isn't currently available. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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