#electronicsproject

Solenoids go clicky-clacky 🔩🔊🤖

Fruit Jam RP2350B credit-card mini computer with all the fixin's 🍓🍇💾

We were catching up on a recent Hackaday hackchat with Eben Upton (https://hackaday.io/event/202122-raspberry-pi-hack-chat-with-eben-upton) and learned some fun facts: such as the DVI hack for the RP2040 was inspired by a device called the IchigoJam (https://www.hackster.io/news/ichigojam-combines-strawberry-and-raspberry-to-deliver-a-raspberry-pi-pico-powered-educational-micro-66aa5d2f6eec). We remember reading about this back when it was an LPC1114, now it uses an RP2040. Well, we're wrapping up the Metro RP2350 (https://www.adafruit.com/product/6003), and lately, we've been joking around that with DVI output and USB Host support via bit-banged PIO, you could sorta build a little stand-alone computer. Well, one pear-green-tea-fueled-afternoon later we tried our hand at designing a 'credit card sized' computer - that's 3.375" x 2.125", about the same size as a business card (https://hackaday.com/2024/05/07/the-2024-business-card-challenge-starts-now/) and turns out there's even a standard named for it: ISO/IEC 7810 ID-1 (https://www.iso.org/standard/70483.html).

Anyhow, with the extra pins of the QFN-80 RP2350B, we're able to jam a ridonkulous amount of hardware into this shape: RP2350B dual 150MHz Cortex M33 w/ PicoProbe debug port, 16 MB Flash + 8 MB PSRAM, USB type C for bootloading/USB client, Micro SD card with SPI or SDIO, DVI output on the HSTX port, I2S stereo headphone + mono speaker via the TLV320DAC3100 (https://www.digikey.com/en/products/detail/texas-instruments/tlv320dac3100irhbt/2353656), 2-port USB type A hub for both keyboard and mouse or game controllers, chunky on-off switch, Stemma QT I2C + Stemma classic JST 3-pin, EYESPI for TFT displays, 5x NeoPixels, 3x tactile switches, and a 16-pin socket header with 10 A/D GPIO + 5V/3V/GND power pins. The PSRAM will help when we want to do things like run emulations that we need to store in fast RAM access, and it will also let us use the main SRAM as the DVI video buffer.

Leftovers & layout - WLED board revision A completed!

Sunday night, Babyada went to bed early, so we finished the capture and layout of our WLED board. Thanks to all the suggestions, we were able to implement quite a few!

For power, use USB C PD with switch-select or DC up to 24V; they are diode-OR'd together with PMEG3050

https://www.digikey.com/short/zv22b0pq

into a massive 5A 24V fuse

https://www.digikey.com/short/43qwwtwm

For the 5V regulator, we picked NCP718ASN500T1G

https://www.digikey.com/short/bb9ncc0n

- it's linear, but we don't need a lot of current at 5V. For 3.3V, we went with our trusty TPS54202

https://www.digikey.com/short/c1wnnf94

Upon request, we kept the ICS-43434 I2S microphone

https://www.digikey.com/short/28zwrrhz

and added an IR 38KHz receiver. For external connectivity, there's an ADC/DAC/GPIO #27 breakout on a JST SH 3-pin and I2C on a StemmaQT/Qwiic 4-pin.

We also added a 2x3 breakout header with 3V, GND, and 3 more GPIO so you could connect an external microphone, IR receiver, buttons, or rotary encoder. The terminal blocks have three 5V level-shifted outputs with 100 ohm in-line resistors and power/ground pairs for each. If you need just one more LED strand, the fourth 5V signal is on the 2x3 block.

Rounding out the design are four mounting holes, a reset button, GPIO #0 user button, GPIO LED, and an individual NeoPixel, which could be useful for testing. It's still pretty small, 2" x 1.3". With an ESP32-Mini module, we can pick a PCB or wFL antenna port, and it's an easy swap to make it use an ESP32-Pico, which has 2MB PSRAM.

bq25185 + TPS61023 = USB or Solar lipoly with 5V output 🔋☀️🔌

We spent the weekend tweaking our bq25185

https://www.digikey.com/short/8hd2778w

designs and made one basic breakout for this flexible battery charging chip. Then, we made a board with a 3.3V buck output to charge the battery with a USB or solar panel and got a clean and consistent 3.3V out. With both of those working, here's a design for a version that has a 5V booster with the TPS61023

Metro RP2350 is wrappin' up testing ✨🐢

This week we got our Metro RP2350 boards

https://blog.adafruit.com/2024/11/11/metro-rp2350-now-with-bigger-better-rp2350b/

back and after fixing the pin direction and rerouting

the whole thing, it came up and pretty much works perfectly! Just one component needed a swap - we were able to test all GPIO, analog inputs, MicroSD slot, PSRAM, LEDs & NeoPixel, user button, I2C/SPI/UART, aaand power supplies. The 5V supply is great, we got a nice clean 5V out at 2A+ from 12V DC in. The last thing to check is the HSTX port, which gives us DVI access, and it works, thanks to this festive turtle demo!

Adafruit FruitJam is a Mac 384K 🍏💾

The FruitJam board has an RP2350, dual USB ports over PIO, DVI output from HSTX, and the ability to emulate some classic computers. In this demo, we're using it with the Mac 128K-But-With-384K-Instead

It's not quite a 512K or Mac Plus—which had 1 MB of RAM—but it does have the same 68000 core and is running a Mac Plus ROM, so once we get PSRAM going, we could easily expand to much more RAM. Right now, we can run Finder 5.1 and test out the mouse and keyboard, which both work flawlessly. This is super fun—we can't wait to get some of our favorite old games working! FruitJam is still a work in progress; we have to revise the PCB to fix some errors, but you can sign up here to be notified when we get them in stock

TPS65131 split boost converter revision ✅🔧