What are you tinkering?

[Nightshft]

Are hardware tinkering sometimes, tuning, fixing or repairing something, maybe just an evening or two? Wouldn't it be interesting to talk about the small fixes? This is the thread.

I'll start: Just got my Action Replay out of the box after some time, but it wont work today. So I opened it and checked the contents of the 27c256 by reading the chips with the eprommer. It indeed is correct, so next step will be to clean the contacts. I hope to get it running again.

[8 Bit Dreams]

Got some Prototype boards of "Fat Olga",
have built these up and having a lot of fun testing them now

[arcanist]

Fun idea for a thread!

Here's an analog synthesizer I've been working on for a year. My goal is to build something with SID-like features from the ground up, with nothing but opamps and basic components. I started with zero electronics knowledge besides Ohm's law.

One of four stereo channels that will plug into a backplane which I'm currently designing:



The synth is driven by analog voltage inputs, which are generated by DACs driven by a STM32 microcontroller. This interfaces with the Amiga through the parallel port and emulated Amiga through USB serial.

Testing parallel communication:



I'm just about to start writing some tracker software to drive the synth.

[stevelord]

I've been reading about the different Amiga buses. I'm a little apprehensive about working with some of them before I find a way to simulate behaviour. I'm hopefully picking up a Deneb soon which will have a clock port and it looks like that might be the easiest thing for me to start with. I was thinking of hooking up an STM32 to play with and working my way up to Zorro III from there.

[Daedalus]

I wish I had more time for more tinkering! Too many ideas, too little time...

Originally Posted by stevelord

I've been reading about the different Amiga buses. I'm a little apprehensive about working with some of them before I find a way to simulate behaviour. I'm hopefully picking up a Deneb soon which will have a clock port and it looks like that might be the easiest thing for me to start with. I was thinking of hooking up an STM32 to play with and working my way up to Zorro III from there.

I'm currently polishing off my Solas project, which interfaces with the clockport. The clockport is indeed an easy interface to deal with, but with any of the buses it's a good idea to build a basic buffered interface that you can use as a foundation. It provides a layer of safety that reduces the risk of crashing, or worse, damaging the Amiga by mixing up signals or writing at the wrong time or similar, and allows you to easily monitor the bus activity as seen by your device. 74HCT245 chips are good for that sort of thing at standard 5V levels, and if you're using low-voltage controllers (some of the I/O on the STM32 isn't 5V-tolerant), there are similar chips that can do level shifting, but they tend to be surface mount so less suited to breadboard experiments.

I started on the Solas project with an STM32 actually. It's a great chip, but I found it was difficult to get the fine timing I needed, so I switched to PIC chips. They've a slower clock and can be more expensive, but the additional peripherals they include on the chip and the lower-level hardware control make them simpler to interface.

One thing to bear in mind for the clockport on a Zorro board compared to the A1200 original port is that its address isn't fixed - it's typically an offset from the Zorro board's assigned address, so can change as the machine configuration changes. The proper way to access it would be to walk the AutoConfig list to find the Zorro board you want, then access the clockport at the offset address, but for simplicity for development, manually setting the address is probably fine, and is how I currently do it.

Sadly, there isn't a central clockport.library/device/resource that could be used to detect and enumerate the ports and hardware connected, and with so much hardware out there already, creating one now would probably be of little use.

[stevelord]

Originally Posted by Daedalus

I'm currently polishing off my Solas project, which interfaces with the clockport.

I've been following Solas since I read about strim's i2c project, looks really nice! I'd quite like to finish with something that complements the ZZ9000, kind of like an extras board to cover the things it doesn't do. I2C and SPI are pretty high on the list and an i2c clockport interface to a temperature sensor would probably be a reasonable starting point for me.

Originally Posted by Daedalus

74HCT245 chips are good for that sort of thing at standard 5V levels, and if you're using low-voltage controllers (some of the I/O on the STM32 isn't 5V-tolerant), there are similar chips that can do level shifting, but they tend to be surface mount so less suited to breadboard experiments.

Is the clock port slow enough for signals on a breadboard? I've done VGA on breadboard, but it was noisy as. I have an STM32F4 breakout I designed so I can probably build a second board to act as a level-shifting bridge. Is there a reason for 74HCT over other 74-series logic other than price? I've used SN74LVCs on projects in the past and some TI bi-directional level shifters but they're expensive.

Originally Posted by Daedalus

One thing to bear in mind for the clockport on a Zorro board compared to the A1200 original port is that its address isn't fixed - it's typically an offset from the Zorro board's assigned address, so can change as the machine configuration changes. The proper way to access it would be to walk the AutoConfig list to find the Zorro board you want, then access the clockport at the offset address, but for simplicity for development, manually setting the address is probably fine, and is how I currently do it.

Thanks for that. I'd read that it's traditionally mapped as a Zorro II interface and the Deneb is obvs Zorro III so there's some jiggery pokery to be had.

[Daedalus]

Originally Posted by stevelord

I've been following Solas since I read about strim's i2c project, looks really nice! I'd quite like to finish with something that complements the ZZ9000, kind of like an extras board to cover the things it doesn't do. I2C and SPI are pretty high on the list and an i2c clockport interface to a temperature sensor would probably be a reasonable starting point for me.

Thanks! Yep, that sounds like a decent goal to work towards, and clockport cards like that are a good stepping stone. And Strim's board is open source too so well worth looking at.

Is the clock port slow enough for signals on a breadboard? I've done VGA on breadboard, but it was noisy as.

Yep, it's not a particularly fast port, and buffering the signals will help with the noise immunity and using long jumper cables. Analogue signals are a different story...

I have an STM32F4 breakout I designed so I can probably build a second board to act as a level-shifting bridge. Is there a reason for 74HCT over other 74-series logic other than price?

Not really, they're generally my go-to for 5V stuff because they're cheap, fast enough for most things and present very little load while still meeting the TTL thresholds.

I've used SN74LVCs on projects in the past and some TI bi-directional level shifters but they're expensive.

Yeah, it's a different story when you're level shifting, but LVCs are great for subbing into 5V designs and are available as DIP chips too for breadboarding. Those bi-directional shifters are excellent, but as you say, expensive.

[Heywood]

After messing around with Kicad and fiddling around with CircuitPython on the Raspberry Pi Pico, I have made an A600 Keyboard USB Adapter.


Previously I made one using a Teensy 2.0++ but these are approach end of sale and are relatively expensive, also I wanted an excuse to fiddle around with CircuitPython.


https://github.com/thinghacker/Amiga...ardUSBAdapter/