In the meantime though I've had emails from a few people who've been following along. Some have pointed out errors (thanks, I'd already caught most of them!), most have wondered if I'll be selling completed units or kits (more on that later), but one gave me a bit of pause. After nicely pointing out a few mistakes I've made, they wanted to know if I could help with faultfinding their factory-fitted memory unit by checking some signals & making a couple of measurements on my MU-7700.
Thing is, I don't have one. Never have…
Oh, I've used one - a couple of times, years ago, on a friend's set - but I've never actually owned one. On and off I've kept an eye out for one (or a set with one fitted) on the usual places, but either I've been too slow or they've been overpriced. Really, 12 memories isn't worth that much except to the completists who must have one of everything (I'm definitely not the Pokémon type!), and I've never really liked the idea of modifying the set too far from standard to increase that number e.g. by replacing the memory switch.
In the end, with a bit of time on my hands & the desire to get back into electronics & SWL as a hobby, I figured the simplest way around all those issues was just to design my own memory unit from scratch. And here I am…
About the faulty MU-7700: between us we did manage to nut out what was wrong with it. It'd been intermittently not storing/recalling (or incorrectly storing/recalling) frequencies for a while, before eventually failing. We narrowed it down to a problem with one of the NAND gates in Q24, it came good while poking around, and inspection showed several fractured/cold joints on that IC. Re-soldering them seems to have fixed it.
As for errors: Yeah, I found a few silly/dumb mistakes during construction and initial testing, and a few more during functional testing. There's also a few other improvements I'd like to make before release e.g. extra I/O for further expansion. All the corrections / mods / improvements are being incorporated into the schematics and, just to be sure, I'll probably do another spin of the main board (after I get the software working) to make sure I've really got it right.
Ah, the software! Let's just say that one problem I keep bumping into is slight differences between the standard Arduino environment and my preferred environment, embedXCode. There's no way in hell I'm going to do it all in the Arduino IDE - but, since I want to release the source for others to play with, I need to make sure it compiles and works in the standard Arduino environment.
(That, and
structs. If you're familiar with structures in most variants of C then a quick look at the ways, means, and pitfalls of creating/using structs in Arduino should be enough to make you cry…)And finally, a couple of people asked about kits or prebuilt boards. Frankly, in most cases it's just not worth it to either me or you - boards are cheap to get made, you can probably buy the parts cheaper than I can, postage in/from Aus is expensive, etc. I'm more than happy to assemble, program, & test a few for people who are unable to find parts, solder SMD, etc - but I can't see that being useful to more than a handful of people.
Realistically, what's the market for this thing? People who (a) own a FRG-7700, and (b) don't already have a memory unit. Maybe an additional few who (c) already have a memory unit but want to play with the extra possibilities of a microcontroller-based one.
Anyway, I'll think about that. More when I actually get it finished and released…
No comments:
Post a Comment