Category making things

Microchip PICkit2 to DIP40 Adapter

Okay, so this post is going to contain lots of babbeling as I try to get my thoughts together…

First off, it seems that I made a bit of a mistake with this SIDbox I’m working on. The mistake stems from my thinking that the PIC18F452 is part of the PIC18F4520 and can thereby be programmed with the PICkit2 which I have. I was wrong.

Based on this faulty thinking, I both built the PICkit2 to DIP40 adapter (photo gallery retired) which you can see above and included support for using this programmer in the SIDbox (photo gallery retired) I hope to build.

So now I’ve got some hardware / connectors on the SIDbox PCB which are pretty much useless as the device would normally work.

At this point I have two choices…

The first is to build a new PIC programmer (probably connected to a serial port) which will properly flash the PIC18F452 using the 1×6 pin header found on the DIP40 adapter (photo gallery retired) and the SIDbox (photo gallery retired) and use the existing hardware layout and order the PCBs.

The second option is to use a newer PIC, the PIC18F4620, on the SIDbox instead. This has the advantage of being completely compatible with my programmer and thusly the adapter and the programming hardware on the SIDbox board. However, there appears to be a bug in the hardware of the PIC18F4620. The end result of this bug is that one can’t use a MIDI output directly from the chip. So, I’ll have to add some additional hardware to provide MIDI output. On the upside, this extra hardware (the MIDIbox IIC MIDI module) provides for MIDI LEDs, making part of my existing design redundant. That means some board space is freed up for the new hardware.

So, at this point I’m not completely certain what to do, but based on the responses I am getting to this post at the MIDIbox forums, I think the second option is going to be the best one. In fact, I’m going to change the schematic and start laying out the board for this now. Just in case I decide that’s the best way to go.

SIDbox PCB Layout
(Click for more of the SIDbox album…)

Nope, there’s not much in the SIDbox (photo gallery retired) album yet, but I do have what I believe to be the final schematics and PCB layouts. I’m just waiting on some parts from Mouser and Digi-Key to arrive so I can confirm the desired layout, then I’ll place the order for everything.

Also, here is a post I made to the MIDIBOX.ORG Forum about the project:
Continue reading: Cut to save page space… →Continue reading: Cut to save page space…

Well… I just ordered about $150 worth of components for the SIDbox project. This is everything needed to build the first prototype except etched end panels, the PCBs, and the power supply. I’m waiting to order the PCBs until I can confirm the switches work as expect. The power supply is somewhat dependent on the type of SID installed in it. And the etched end panels… Well… They are just a finishing item, so those will wait until I’m certain that this thing actually works.

Also, I’m nailing down some final things on the PCB layout. Just… Tweaks and stuff.

The single hardest part of this SIDbox to figure out is the power switch. I can’t seem to find a properly documented part with the proper size hole for the panel, the pin layout, etc.

SIDbox PCB (Click for 300dpi)

Yep, there it is. The first draft of the PCB for the SIDbox thingy I want to make. I need to do a good bit of checking to be sure I’m happy with it, but if I am, I’ll likely be ordering 5 of them. Then the Mouser parts order will be placed… Then (hopefully) I’ll put it together and it’ll work. I hope.

For now, though, I’m going home. On the way home I’ll stop to get something tasty (and fairly good-for-me) for dinner. Maybe tonight I’ll have a good beer, too. I’ve done enough electronics work for one evening.

Oh, and there is a copy of the Boondock Saints waiting for me to watch. Yes, I’ve never seen it.

UPDATE: Whoops, I just realized something that’s wrong with this… My hope is to solder on just the socket and pin header, then program the chip using my PICkit2 programmer. Well, without a line running from JP1P2 to V_DD on IC1 (the PIC) I won’t be able to do it. Must change that…

Also:

· Rename all parts appropriately.
· Clean up BOM with new part names.
· Move JP1P1 indicator arrow to other side to align with the PICkit2’s indicator. Done.
· Establish values for the resistors for the LEDs.
· Also, maybe fix how the LEDs are connected. Currently the polarity for PWR_LED is different than MIDI_IN_LED and MIDI_OUT_LED. Maybe fix this. Probably should if kits may be sold. Done.
· Connect JP1P2 to V_DD on IC1 so IC1 can be programmed with only JP1 and itself installed. Done.

Click for full res…

Hmm, I think I’m done with the SIDbox schematic. Also, all the parts have packages matching the BOM I’ve been making up. I also replaced the standard MIDIbox programming header with one that matches the Microchip PICkit2.

Uhm… That’s all. I think it’s time to start laying out the PCB. I’ll probably do that tonight or tomorrow.

Over the past couple days I’ve been attempting to learn to use CadSoft EAGLE better. I think I’ve come pretty far on it, and I’ve started working on a project that I’ve been wanting to tackle. That is, building a stand-alone SID module. Think of something about the size of an external hard drive, with MIDI IN / THRU / OUT jacks, and a pair of 1/4″ jacks for audio in and out.

Well, I think I’ve gotten pretty far on it. If any of you are interested in seeing the schematic as it stands right now, please take a look here: SIDbox Schematic

Also, if any of you who are a bit more electrically inclined could take a look at the power supply, that’d be really great. I’m not sure it’s right… I think so, but I’m not certain.

For what it’s worth, I’m hoping to feed PWR_TIP and PWR_RING 15VAC from a wall wart.

If the SID is a 8580 (the newer version) instead of a 6581, then I’ll replace the 7812 with a 7809 (since it only needs 9 VDC) and replace a few of the caps in the SID portion.

Completed Casio SK-1 MIDI Adapter
(Click for full res.)

On the up side, I completed the PCB for the Casio SK-1 MIDI adapter that I’ve been working on. On the down side, it doesn’t work. After reassembling the SK-1 after cleaning it, everything seemed to work great. Then, after I hooked up power, fitted the PCB into the enclosure (without gluing it yet), and attached the ribbon cable to the SK-1’s keyboard connections, the SK-1 just makes a humming / buzzing sound. I think the problem is likely some part I missed soldering on top of the board or something. Or possibly a bad PCB-side connection on the ribbon cable.

When making one’s own double-sided PCB, the holes aren’t plated on the inside with metal, so one has to solder parts on both the top and the bottom of the PCB. It was a bit of a hassle to solder things on both sides, but I thought I it taken care of in most places. Maybe I’m wrong, though… Ah well, tonight (or sometime this weekend) I’ll remove the PCB, remove the power lines and ribbon cables, and double-check everything against the schematic.

Here’s some of the pictures from my work on this last night:

· Resharpened PCB drill bits, acquired from eBay. They are really, really small. The shafts on those bits is 1/8″.
· A very unshaved me, wearing a respirator and safety glasses. Both are needed as drilling and cutting PCBs makes lots of fiberglass / epoxy dust.
· One of the bits (26 mil, I think) in the chuck of my Dremel.
· The pile of parts needed for assembling the adapter, including some spare resistors sacrificed for their leads, which were needed to solder vias.
· All vias soldered, and jumper A placed to turn off wrapping of notes from outside the keyboard’s normal range.
· All parts (except for microcontroller, ROM, and wiring) attached to the board.
· Completed board, with power wires and ribbon cable.
· Ribbon cable attached to Casio SK-1’s keyboard connection.
· Power wires attached to the external power jack and the PCB fitted next to the speaker.

So, that’s that. I’ve still got more to go with regards to fixing everything. I know it’s getting power… I just don’t know what else it is doing yet. By the time I had the board installed it was nearly 11pm and I’d been working on everything for about 4.5 hours. I needed a break. Hopefully things will progress further tonight / this weekend. At least I don’t work until Monday or so.

Hmm, so yesterday I added two more pots (2Ω, wired in series with the other ones) as a fine tune adjustment on my Elenco XP-720K (photo gallery retired). Despite being a bit unattractive it was working great, until I went to use it today. I turned it on, off, then back on, and the fuse blew. It’s just a small 1A fuse, so maybe the shock of bouncing it around for a bit caused it to go, but it still worries me a bit.

I don’t know what could have caused this, except for something being shorted out. But I had simple banana plug leads between it and my meter (to set it to exact 5.000VDC) and nothing else. I guess I’ll go get some more 1A fuses, stick a new one in, and wait and see if the problem comes up again. I’m hoping it was just a cheap fuse and thermal / mechanical stress on the fuse itself. Hmm, I guess it did get shaken around quite a bit while I was drilling out the extra holes in the front panel. The steel is really hard, so it took a bit of work.