thomerow

Hey guys! I'm very sorry for seemingly "ignoring" your posts! Somehow I managed to misconfigure the notification options and didn't notice your replies. I must admit that I haven't gotten very far with my SID-project in the last few weeks (at least not as far as I'd like to). The main problem is, of course, the lack of free time. I could only manage to spare one or two days a week for working on it. Nevertheless I learned quite a few things so far! I programmed a simple firmware parsing midi messages and converting some of them into SID instructions, learned about the perils of static electricity the hard way (I killed 2 (!) SIDs while experimenting with them) and etched two PCBs using the "direct toner method" (one of them double sided!). I even own an oscilloscope now. :ahappy: So the whole thing is producing sound, and by "hard wiring" some midi contol messages to some basic SID-features like the ADSR-envelope, the filter frequency and the resonance I am able to play it "monophonically" using my old midi-keyboard (which has some assignable control dials). This is what it looks like so far (yes, the board holding the sid is a modified version of the MBHP SID module lacking the audio input and the voltage regulating circuitry): @TK.: Thanks for the link to the source file! I just skimmed through it and will definitely have a closer look into it because so far I'm not taking account of the rising and falling edges of the SID clock at all. I haven't had the chance to advance the whole thing for three weeks now, but I will definitely post again if I have put everything into a nice case and added some buttons and a display. (IF that day ever comes…) Regards, Thorsten

Yes, of course, you are right. I even read that somewhere before but must have somehow forgotten it. Thanks for your advice regarding the "problem" with the current draw. Unfortunately the next time I will get to carry on with my project is this weekend. I'm really looking forward to it. Coincidentally the link you recommend is the very first page I came across when looking for a possibility to connect a SID to a MCU. It sort of was the starting point for all my further research regarding this topic.

OK, I will have another try tonight… Just found it strange that without doing anything at all the chip already needs more power than the "typical current draw". So there is nothing unusual about this behavior? Should I be concerned if it draws 100mA permanently?

Hello forum! This weekend I started my first experiments regarding a microcontroller, two 74HC595s and a MOS 8085. Unfortunately I didn't get very far because both SIDs I have lying around semed to draw too much current on the 5V pin. Hopefully I didn't fry them both by doing the following (I haven't connected them to the full voltage level at any time): For a start I connected only the 9V pin to a power supply preset to the right voltage but with the current turned completely down, the 5V pin to a power regulator connected to the same power supply, the reset pin to 5V and the ground pin to ground. A 1MHz oscillator (also supplied by 5V) is connected to the clock pin. Being very cautious I have a multimeter attached to each the 5V and the 9V inputs. When I slowly turn up the current on the power supply, the 9V line shows very little current, but the 5V line is already drawing more than 70 mA at about 3 volts. What's happening here? Have I unluckily bought two broken SIDs from two different persons on Ebay?

Thanks for the warm welcome, nILS! That's exactly the type of answer I was hoping for. On to further research! This is gonna be a long weekend :ahappy:

Hello MIDIbox-forum! I have a general question regarding the design of the SID module. It's not directly MIDIBox SID related, but I hope it's OK if I post my question in this forum nevertheless. The only thing I am looking for is a cue in the right direction, and I thought perhaps someone will take the time and write one or two sentences to clear things up. First a quick explanation why I came here: In the last couple of weeks I have been working my way towards a possibility to drive a MOS8580 with an Arduino. I (a total microcontroller newbie, by the way) am doing this mainly for the fun of it and to learn something about microcontollers and electronics in general. The main problem with connecting the Arduino resp. Atmega328P to a SID directly is the lack of a sufficient number of pins, so I googled for a possibility to convert serial to parallel data. Of course, relatively quickly I learned about shift registers ;) . When I looked for examples concerning the connection of a SID to a microcontroller, I found out about the MIDIbox SID project and looking at the schematics discovered that the "SID module" uses two 74HC595s to drive the SID's address and data pins. Now here's the thing which confuses me about that and which I hope someone can clear up in a few words: The two 74HC595s are connected to the PIC via the same clock and latch pins and the serial data is looped through the first 74HC595 through port O8 into the serial input of the second 74HC595. If I'm not mistaken, this means in general that the parallel output pins of both chips are always exactly in the same state at the same time. How on earth does the SID know in which moment the address is sent to it and in which moment the data arrives? Is there a slight time-offset between the moments the output pins of the 74HC595s are set which is just long enough to differentiate between addresses and data just because the serial data has to run through one of them? As stated I would be happy about a short clarification but would also understand if my question is ignored because it is slightly off topic. Kind Regards Thorsten