Pi1541 Pi-Hat

So, one of my other hobbies are retro-computers. Specifically the Commodore 128. I had this computer as a kid and it still holds a strong place in my heart. I recently acquired a Commodore 128DCR on eBay and have been playing with it again. But as with all things retro, there is a strong community of like minded people who have built gizmos, gadgets, and mods for these old computers. Why? Because we could! 🤓

One area that has gotten a modern touch is in regards to the storage for these computers. While there are plenty of old Commodore 1541, 1571, and 1581 disk drives out there (remember these things sold like hotcakes back in the 80’s) and there is plenty of OLD media for these devices out there (again – “hotcakes“), floppy disks (like all things) degrade over time and their quality becomes spotty at best. And it’s not like companies are busy making new 5.25” floppy disks anymore. Plus floppy disks were not exactly easy to use or store to begin with and with only 320KB of space on them – well, you start get the picture – a lot of people’s collections started to look like this.

So now, thanks to some very creative people, there are two main alternatives born out of the emulator scene. One is the very popular SD2IEC device and the other is the Pi1541 Pi-Hat. The great thing about these is that they use very common camera SD cards to store “images” of the old floppy disks and a 64GB SD card can hold just about every software title ever produced for the Commodore 64 and 128 with plenty of room to spare for your own creations!

Both of them have their merits and I’m not here to advocate either one. In fact, while this article is about the Pi1541, I also have a SD2IEC device.

But I also wanted a Pi1541 because it, unlike the SD2IEC, provides a 100% (or close to it) emulation of a Commodore 1541, 1571, or 1581 disk drive. So much so that it’ll even fool some of the best copy protection schemes out there and will even fool GEOS.

So, while I could have purchased a pre-built Pi1541, I opted for a “kit” that I could assemble myself because I love doing that. So I ordered one off of eBay. Actually I ordered two of them from two different sellers but only one of them (the link just above) has arrived as of this posting. The other seems to have gotten lost in the Matrix.

I really like the kit that I did get because it comes with ALL the needed parts except for the Raspberry Pi. Not a big deal because I have a few lying around. I grabbed one of my spare “3B’s” and sanctioned it for use as a 1541 “disk drive.”

The one big downside I saw right off the bat is a complete lack of any real instructions. So I tracked down the person who designed the circuit boards to try to glean some instructions. While I got a bit more there were a few things that I could see some novices having a bit of trouble with so I thought I’d put together a complete list of instructions to help other folks out.

Let’s start out with some helpful links:

Some Important Tips:

  1. You need to have a good soldering iron (Amazon). It doesn’t have to be super expensive but it shouldn’t be cheap either. And a small tip for it will help with the solider bridges (see below).
  2. Have some good solder. I prefer a 0.8mm, 60/40, rosin-core solder. You can find these on Amazon.
  3. And unless you’ve got superhuman eye-sight I suggest a pair of helping hands with a magnifying glass. (see point #1 above) Again, Amazon is a good place to find them.

Piezoelectric Speaker

It was not made obvious which way the speaker was to go in but the way you put it in is definitely important. First off, until you have everything done, DO NOT PEAL THE STICKER OFF THE PIEZOELECTRIC SPEAKER! The sticker shows you which terminal is the positive terminal!

If you did remove the sticker then the positive terminal is usually the longer of the two.

LEDs

The LEDs also were not clear but they can be easy to deduce. The longer lead is the positive lead (anode) and, if that’s not clear, there is a “flat spot” by the negative lead (cathode).

Solder Bridges!!!

Now, it was REALLY NOT CLEAR AT ALL that you had to do this, but you first have to create some solder bridges on the circuit board to configure it!

Please refer to this page and then this page. I know that the first page I gave you refers to an older version (V2) of the circuit board but it’s information on the solder bridges you have to create still apply to the newer version (V4)! If you ordered the same kit I did (which I highly recommend) then you will want to choose option B!

This is where the helping hands and magnifying glass REALLY COME IN HANDY!

Here are the solder bridges I made on mine.

7406 logic IC

Take care with the 7406 IC chip. The pins can be easily broken off. But you have to bend them in just a bit so they drop into the through-holes on the circuit board. I recommend a pair of long-ish needle nose pliers to grab all the pins on one side at once and slightly bend them in just a bit.

The “notch” at one end of the chip should match with the “notch” on the circuit board. When in doubt, the “notch” on the chip should point towards the RPi 40-pin header.

LED Placement

You should have gotten two LEDs – red and green. One is for the power indicator and the other is for indicating drive activity. It really doesn’t matter which color you use for which indicator and really comes down to personal preference. There also isn’t any reason you can’t replace the two LEDs that come with the kit and replace them with colors of your own choosing.

What DOES matter is that you put them in the right way so that the anodes and cathode are in the right way. Both LEDs go in the same way. If you look at the top of the circuit board so the RPi 40-pin header is towards the top and the serial ports are to the left then the anodes go to the left and the cathodes go to the right.

Enable Speaker Jumper

Something else that wasn’t very clear is that there is a two-pin header and a jumper for it in the kit that you use to enable the speaker. This header and the jumper go into the part of the circuit board that says SPKR_EN. This way if you decide you don’t like the mock drive sounds then you can remove the jumper to disable the speaker.

Also note the correct placement of the piezoelectric speaker. The positive terminal is towards the RPi 40-Pin Header.

Resistors

If you don’t know the color codes of resistors then you really shouldn’t be doing this. But if you’re brave anyways, please note the correct placement of the resistors.

Finished Product

Here are some pictures of the finished product.

4 thoughts on “Pi1541 Pi-Hat

  1. Thanks for sharing, Galen! I’ve not heard of this product, sounds interesting indeed. I have the SD2IEC and have enjoyed playing with it immensely. I’m curios, what are the little switches on the side of the Pi1541 for, the ones labelled SW1 – SW5? They look like 3.5mm audio jacks in the pictures (I’m guessing they’re not though).

  2. Galen, way cool…now if I could find a 1970s Ducati 250 motorcycle I’d be almost as happy as you are with that Commodore! Best to you old friend…dsgeorge

    1. Dick! It’s good to hear from you. Yeah, I very rarely get to use my electronics skills these days so now that the kids are all grown and pretty much on their own I’ve been getting back into some of my hobbies.

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