Metro RP2350 take 5 🔄🌟🤞

Don’t use the Raspberry Pi 2040 to build a DCC decoder.

It’s not really wrong, of course, and it gives you ridiculous amounts of computing power, but to get that you need miles and miles of extra components. Like a dozen of decoupling capacitors, an external oscillator, and of course an external flash memory. You can maybe do that sort of thing in H0, but for real model trains, it’s just not ideal. Pick something like an ATTiny or STM32C0 (I’ve done both for different projects): Cheap, just one or two decoupling capacitors, no external oscillator required and no external flash memory needed either.

The versions of the RP2350 with built in memory may be a better idea, once they fix the GPIO issues anyway, but still, there’s the oscillator and just way too many capacitors.

(Some of these concerns may be different if you want to add sound support, which requires more memory anyway. But I’d argue that sound in model railroads is a mistake anyway. I’ve never seen an N scale locomotive that sounds good, it’s all just an annoying expensive gimmick.)

Also while we’re at it, don’t use a cheap standard bridge rectifier. The steep slopes of the DCC signal mandate a really fast rectifier, typically Schottky diodes. This is particularly important when you have RailCom on your layout. You may need four individual diodes instead of one rectifier, but since you won’t need all the capacitors of the RP2040, you still win out in the end (it’s also typically smaller than the rather large SMD standard rectifiers).

Testing Dark Castle with audio on the RP2350 Fruit Jam 🕹️🏰

Jepler spent a bunch of time this week working on getting audio working on the pico-umac port https://github.com/jepler/pico-mac/tree/rp2350-fruitjam to Fruit Jam

. Audio on the hardware we're emulating is pretty straightforward: every scanline of the video generator also pops out one byte of PWM data. We have 370 horizontal lines—352 visible and 18 during the vsync—and a 60.15 Hz refresh rate for 22.255 KHz audio approximately. That data is written to $1FD00 http://www.mac.linux-m68k.org/devel/plushw.php . That data is being piped over I2S to the MAX98357

and to a speaker for now.

So, of course, the first thing we have to try out is Dark Castle

"See" the Sounds of Classic Mac Audio 🔊🍏

We're working on the Pico-Mac port https://github.com/jepler/pico-mac/tree/rp2350-fruitjam to Fruit Jam https://www.adafruit.com/product/6200 and one thing we really want to add is sound support for classic Mac games and HyperCard stacks.

Browsing HyperCard stacks on our RP2350-based Fruit Jam 🍏📂

With a little more tweaking, we've got a nice big 12MB disk image loading into our Pico-Mac port https://github.com/jepler/pico-mac/tree/rp2350-fruitjam to the Fruit Jam https://www.adafruit.com/product/6200 — that 16MB of internal flash is coming in super useful now!

That means not only can we run System 6 but also install some nice software like HyperCard https://en.wikipedia.org/wiki/HyperCard !

🧑‍💻 It's here! The Metro 🚇 RP2350, expand with the 🎵 DAC7578 & FPC Breakout. And a fresh 🥧 update to the Raspberry Pi Beginner guide completes the new product tour this week! https://www.adafruit.com/new

First of the Bones Rises – RP2350 Adalogger 🦴

With the RP2350 chip in wide distribution , we're now able to come up with a lot of variants of our popular RP2040 "Bones"

https://blog.adafruit.com/2023/01/22/rp2040-feather-bones-for-a-few-different-varieties/

that ended up becoming a dozen different boards.

We're starting with the 'Adalogger' design folks love: with a microSD card socket that is wired for SPI or SDIO. A separate regulator allows the I2C/uSD to be powered off completely for ultra-low power usage. This didn't make as much sense for the RP2040 because it was not a particularly low-power chip. There's also a Stemma QT port for plugging in external sensors.

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!