lylehaze

If I ever start working again, I hope to add some MIDI controlled RGB lighting to my office.. now I know who to talk to when that time comes. :-) Way to go! LyleHaze

I Wonder if MIOS clears these before you can read them? From the 18F452 datasheet: 3.0 RESET The PIC18FXXX differentiates between various kinds of RESET: a) Power-on Reset (POR) b) MCLR Reset during normal operation c) MCLR Reset during SLEEP d) Watchdog Timer (WDT) Reset (during normal operation) e) Programmable Brown-out Reset (BOR) f) RESET Instruction g) Stack Full Reset h) Stack Underflow Reset Most registers are unaffected by a RESET. Their status is unknown on POR and unchanged by all other RESETS. The other registers are forced to a RESET state on Power-on Reset, MCLR, WDT Reset, Brown- out Reset, MCLR Reset during SLEEP and by the RESET instruction. Most registers are not affected by a WDT wake-up, since this is viewed as the resumption of normal oper- ation. Status bits from the RCON register, RI, TO, PD, POR and BOR, are set or cleared differently in different RESET situations, as indicated in Table 3-2. These bits are used in software to determine the nature of the RESET. See Table 3-3 for a full description of the RESET states of all registers.

It's a perfectly good question, and I won't answer it for you. :-) Especially in audio, the term "acceptable noise" is an argument in itself. I think Alan Parsons would have a different threshhold of "acceptable" than say Jimi Hendrix. One made his name by eliminating noise, the other by amplifying it. So I'll cop out and give an engineers answer. A switching mode supply works (in part) by "chopping" the incoming voltage at a varying dwell angle, using this to adjust the resulting voltage. This turns out to be way more efficient than linear supplies (less heat to dissipate) but it can produce a lot of noise, expecially near the switching frequency. There are some things the designer can do to reduce that noise, but if it's being mass-produced, companies trying to save every penny will reduce or eliminate those "unnecessary" parts. So, as a designer, the first call is to reduce the emission of noise from the power supply itself. The second call is to adapt your audio circuits with a low-pass filter to further reduce these high frequencies. For something like an ADC (audio digitizer) you might even choose a fixed frequency power supply and filter that frequency in software (though that is a bit extreme). Another trick is to use a SMPS to feed an "ideal" voltage into a linear regulator. i.e use a 7.5 volt SMPS to feed a 7805. This gives SOME advantages from both worlds, but it's not perfect. In the end, what is "acceptable noise" is up to each individual. It does make a difference. As I said before, the MB64(e) does not directly handle any audio (as far as I know) so you are free to use SMPS without any ill effects. Please pardon my verbose response, but there's always a lot of power supply questions around here, so I try to be as complete as possible in my answers. LyleHaze

Welcome! Speaking in general: Switching supplies are great for digital projects, but can be a source of electrical noise if you are building an analog project (audio). I'm not saying that you can't use switching for audio, just that you may have noise issues to deal with. Getting back to your specific application, The applications you mentioned (MB64E X 2 and lamps) should have no problems. The MB64E is a digital project, and the lamps are, well, they are lamps. One thing to watch out for. Many SMPS supplies have a minimum current that must be drawn for the regulator to work. One of your examples even calls it out in the specs. You will need to make sure that you always load the supply by at least that amount. This can suusally be done with a few big power resistors (which may get warm). There are Ohms Law calculators on the web that will help sort out the correct values. A popular trick for a cheap "bench" power supply is to convert an old PC supply. Just as above, you will need to "load" the +5 and possibly the +3.3 volt supply to make it work. Also, If you're using a PC supply, be SURE to fuse your project, as those supplies can deliver enough power to do some real damage before they trip themselves out. Have Fun, LyleHaze

About the label of "USB Audio Device", that may be from your OS. The interface MUST present itself as "Class 1, Subclass 3" or it will not be handled as a USB MIDI interface. "Class 1" is Audio Class, "Subclass 3" is MidiStreaming. Regarding changing the number of ports, where do I look to see the code? maybe I can see something that will help. LyleHaze

sorry, I'm late again. It happens to often, they will probably put it on my headstone: Here lies the late LyleHaze. Yes, the little PICKit2 is the most bang for your buck that you'll ever find. And it's small enough to wear it as jewelry. :-) The only thing better than a PICKit2 is a good bootloader, especially if it is run by MIDI. ;-) Have fun, and tell us what you build with the DSPic! LyleHaze

Thanks to all. I'm typing now on an Acer Aspire One. Nice little machine, comes with XP. Only about 50 bucks more than a low end desktop box, but it should cover that just fine along with being VERY portable. Nice little machine, but I'll need a "regular" keyboard and mouse for dev work. Thanks again to all for the advice. I really like this little thing. LyleHaze

Thanks to all for your info. I'm going out today to look for a Acer Aspire One. Most of the time it'll be a "desktop" machine, but being a netbook when I'm mobile can't hurt. I checked specs against my wifes older XP laptop, and it doubles her HD and ram, and improves the processor clock slightly as well. Hard to beat for $350. Thanks again for the feedback. Maybe once I get this setup I'll be able to get into the CVS all by myself! LyleHaze

Stryd: My existing box is 98SE, not XP. I tried Ubuntu on it, but couldn't get the video right. Since it's my "second" PC, I would prefer windows, only because it is the most "universal". Not because I like it or anything. So after reading up a bit more, I have found a under 400 desktop machine that comes with Vista AND XP-Pro. But it's weak on RAM, so that would add a bit. After reading the article Wilba pointed me towards, I'm giving serious thought to getting an Acer Aspire One as a desktop replacement. Sounds silly, but it could be the best of choices. It is admittedly a bit underpowered, but ALL of the cheap-as-I-can-get computers I have looked at are. It comes with 120G HD, 1G Ram, and XP. I know the ram seems a bit light, but I think 1 gig is enough for basic Eagle, GCC and MPLAB on XP, right? The best part is that when I go "on the road", I can take it with me. Being ultraportable is handy for a lot of things. Checking E-Mail and Mapquest from hotel rooms, downloading camera cards to the HD. All that is BONUS that a cheap desktop won't be useful for at all. I "lose" having a built-in optical drive, but I can convert a drive I already have to USB for just a few bucks. I'm asking for opinions. If you think I'm right, or if you think I'm wrong, speak up. I know I'm getting a "cheap computer", and I will NEVER try to play games on it. Think it's good enough for what we do around here? I need sleep. LyleHaze

I've been limping along with an antique for too long. Now I'm looking for a new computer. I have choices to make: I found a cheap, underpowered PC for $300 that comes with XP Home. The cheap price is tempting enough, but it won't go above 1 Gig RAM. I found a more powerful Dell available for about the same amount. But the Dell comes with Vista, not XP. Funny enough, Dell offers XP for an EXTRA $150. That increases the total cost by 50%, just to get the "old" OS instead of the new one. That's about the stupidest bit of marketing I've ever seen. Anyway, the people here would be the best gauge of how well Vista works for me, as I'll be using it for developing MBox stuff, running Eagle, GCC, and stuff like that. I am NOT looking for a cost-alot-go-fast gaming machine, just for solid productivity in programming and board design. Any suggestions from more experienced people are invited. Thanks, LyleHaze

From "Universal Serial Bus Specification" 9.2.5.1 Power Budgeting USB bus power is a limited resource. During device enumeration, a host evaluates a device's power requirements. If the power requirements of a particular configuration exceed the power available to the device, Host software shall not select that configuration. USB devices shall limit the power they consume from VBUS to one unit load or less until configured. Suspended devices, whether configured or not, shall limit their bus power consumption as defined in Chapter 7. Depending on the power capabilities of the port to which the device is attached, a USB device may be able to draw up to five unit loads from VBUS after configuration. So yes, but it is the responsibility of the client device to limit its current draw until it is properly enumerated. Do not draw more than 100ma until you have requested and been approved for more (up to 500 ma). The host might choose to deny any power requests if it doesn't think it can power it properly, the client is supposed to honor that. Anyway, that's what the spec says. I know of a few devices that ignore it anyway. I'd love to know how much power the GM5 chip "requests", and how it can power up/down the rest of the circuit based on the configuration response from the host. I have the USB spec here, also the MIDI "class compliant" documents, and will provide them to anyone who asks. LyleHaze

@/tilted/ Truer words were seldom spoken. The raw volume of details that must be worked out, checked, and verified for a new project is staggering. I have designed a built projects from scratch before, but even with this experience, the mixer took longer than I ever dreamed it would. It helps me to remember that I'm doing this for fun. If I start to stress out, then it's time to walk away for a while. If I'm not having fun, then I'm not doing it right. One of the best thigs about a DIY community is that if anyone starts bugging you to get something done, you can tell them to go do it themselves. :-) When this project starts developing again, I'd be happy to offer any help that I can. We may be able to re-use some of the PGA code for this as well. (or maybe not, I don't mind either way). Have Fun, LyleHaze

The classic Amigas could also use a serial-MIDI adapter. There were many circuits online, some were a bit less developed than others (did I say that right?) I have not seen problems like you describe, but if I had a flaky MIDI link, I would look first to the optocoupler on the affected MIDI IN. Optos have a history of being flaky, as well as a documented loss of signal peformance over the device lifetime. On the other hand, they do perform "magic".. carrying a digital signal across an electrical isolation barrier. If you think about it, that's pretty cool. LyleHaze

/tilted/ You are correct, of course. But don't even think of the word "impossible" as long as the cable is laying on the ground. Forklifts, sport shoes with metal cleats, heavy boxes with sharp corners, performers with spiked hair, fools with staple guns, the list could go on forever. Short circuits _MAY_ be impossible under lab conditions, but out in the real world, there are more possibilities than I can count. Be prepared for anything, be suprised by nothing, always keep a roll of duct tape handy. :-) LyleHaze

Phantom power.. There are two possibilities: If the case is not (yet) connected to system ground, which is likely if it's not yet plugged in while you fumble around with the MIC cable: No problem. As there is no return path, there is no circuit. If the case is already connected to ground, probably through some other cable already connected: If you short Phantom power to the case, Phantom power will momenetarily fall to zero volts on that one lead. The phantom power supply and all other devices powering off of it should be unaffected, as each lead has its own "pullup resistor" to V+. Current through the short circuit point is limited to voltage (approx 48?) divided by resistance of the pullup for that wire. ref http://users.otenet.gr/~ATHSAM/Audio_mixer_6_ch_ENG.htm The phantom power resistors are 6.8k to 10k. Worst case would be 48V across 6.8K resulting in 0.00706 amps of current. Hopefully your PS can tolerate that for short periods. If the same short happened and the case was NOT grounded, the "best available" path to ground might be through the operator. I recall a news story about a baptism ceremony a few years back in Texas. Standing in a pool of water, reaching up to a hanging Mic above. The problem was a short, the ceremony was even shorter. I don't claim to be an expert. I'm just posting my understanding of the circuit. I invite others to correct me or discuss this further. Lyle

When a metal case is grounded, it becomes a "shield" to prevent (or reduce) electrical noise from coming in. It works in a way similar to the shield on a microphone cable. Please correct me if I am wrong. Lyle

That is great news.. Works first time! The nice thing now is that you can change from one application to another just by sending a different SysEx file, It takes just a few seconds to change up the application. When I got as far as you are now, I think my first app was the "MIDI Benchmark", since I am on a different computer than most. I wanted to test the MIDI handlers in my computer for speed. It requires no new hardware, and like I said, it lets you test your rig. I see that TK has added an LCD benchmark too. Did you change the battery in your meter? Did the voltages look closer to normal after that? Oh, just because I want you to feel like you got the full experience: If you want to send your core to me I can screw something up and send it back. That way you can get some experience looking for problems. :D Have Fun, LyleHaze

As Dreamer mentioned, check the pots for the LCD, they might just show you something good. Another test would be to connect the MBox MIDI Out to your PC MIDI in. You should get one or more small SysEx messages after the core starts up.. This is the MBox waking up and asking for a program to load. It is possible that SmashTV didn't burn your PIC before sending it out to you, but the chance is pretty small. He does a lot of these things, and he is usually right on target. Troubleshooting is half the fun. :-) LyleHaze

As you guessed, the basic core has only one serial port, and we usually use it for MIDI. (MIDI is a serial protocol at an odd baud rate). So you are correct that you would need more ports to make this work. I have no experience with the LTC, so I'll do a bit of research.. (reading.. reading.. OK, I'm back) I looked the LTC over. It can do the serial voltage changes I mentioned below with a MAX232, but you'll lose the MIDI ports to get the serial port. The IIC module can apparently add more MIDI ports for you. Now we need an expert to tell us if we can use both at once. :-) One other issue to watch out for is the serial voltage levels. "real" serial uses - and + 8 volts (approx, maybe more) But a "logic level" serial port usually uses +5 volts and GND (as it comes out of the PIC). You can use something like a MAX232 to create the odd voltages and do the level shifting. I can't tell if that will be needed without seeing more data on the minidisc player. Finally, there are "standard" MIDI commands for start, stop, song position pointer etc. You may want to support the standards instead of making up your own as you go along. You can learn a lot about MIDI by reading a website like http://home.roadrunner.com/~jgglatt/ There's a TON of well organized information there. A good place to start is http://home.roadrunner.com/~jgglatt/tech/midispec.htm then scroll on down to MIDI Start, MIDI Stop, MIDI Continue But I'm telling you stuff you probably already know. Welcome aboard, have fun, enjoy the friendly community. LyleHaze

Yes, it's OK to hack up a C64 power supply. Since you already ripped the SID from it, it won't make much noise about getting stripped anyway. ;D This message was written on an AmigaOne running OS4. Have Fun, LyleHaze

But.. BUT!! What will your Amiga use? You can't retire an Amiga just for it's power supply. That would be wrong. You won't get anywhere near my Amigas buddy. :-) Have Fun, LyleHaze

I found a Rapid catalog online that shows that part as OK for both 5 volt and 3.3 volt. Your topic is "Crystal Voltage", but this is a crystal oscillator. I want to make sure you understand the difference. This is NOT just a crystal. It's a complete circuit that has a crystal inside it. If your circuit calls for a simple crystal this is not an exact match. [edit] I checked the OPL3 board list, this looks like it should work. Have Fun, LyleHaze

Good First Post. Welcome aboard! If you are using a 7805, the regulator is probably more accurate than the meter. I doubt you will have any problems. If it is a digital meter try changing the battery in the meter. Digitals often read high when the battery is low. If it's not a digital meter, how are you getting readings to two decimal places? ::) Wall wart transformers often give higher voltages than expected, the labels are not to be believed. If the regulator doesn't get too hot under full load, then you'll be fine. If gets too hot to touch, you can either feed it a lower voltage or attach a heatsink. Have Fun, LyleHaze

As far as I understand, 4.1 is a 5 speaker system.(4 + woofer), just as 5.1 is a 6 speaker system. As it is now built, you could support "Quadraphonic" (kids, google it!). Although it should be possible to build two stacks, and "gang" two channel boards (horizonitally) to the same input, then you'd have eight to work with, That gets a bit messy though. I designed it to be as flexible as possible. Every day I hear new ideas that I never considered. Yesterday I was discussing how to use the "spare" op-amps on a channel board to build an audio compressor. A few days before, how to use these for a guitar effects chain. I am REALLY looking forward to getting these into the hands of some of you crazy folks. :-) I should add this: This board was designed as a simple line mixer. It has lots of options that you are encouraged to play with, but in the end each user is responsible for making it work. If you follow the posted build, you will have a fine line mixer. Those who want something very different should consider starting with a regular mixer and experimenting from there. Too many changes at once can make troubleshooting difficult. This is going to be a lot of fun.. ;-) LyleHaze

All the positive regulators (78xx) have the tab grounded, unless you are "stacking" regulators. If you are using a metal case, you may be able to use your case as a heat sink. To do this, I usually insert the regulator from the backside of the board, and I don't solder it until the board and regulator are mounted firmly. A bit of heatsink compound doesn't hurt either. If the case is painted, Sandpaper will clean up a spot for the regulator. DO NOT do this for negative regulators unless you have an insulating sheet and screw, as the tab of those is NOT grounded. Have Fun, LyleHaze