Which Pic?

[jimh54]

I'm new at MidiBox so forgive me if I've overlooked the obvious. Of the many projects on Midibox/ucapps I cannot find any obvious answers to the question of which Pic chip works best with which project. I know there are some differences between the 18f452, 18f4620,and 18f4685. So how can I find out which Pic works best with which project? There is a reference that the 18f4685 is best for the MB-6582 SID project, but how about the OPL-3, and other ones?

I know this is likely posted in the wrong place. So feel free to move it to the correct place.

Thanks

[nILS]

You do have overlooked the obvious ;) Virtually every project start page on ucapps has info on the used processor.

[buhler]

A nice outlook for the future is, that Microchip still considers pin compatible devices. The MBHP started with a PIC16F877, in the meantime PIC18F452 is used, and for memory intensive projects like MIDIbox SEQ V3 or MIDIbox SID V2 the PIC18F4620/PIC18F4685. So long this upgrade path is given, a switch to another microcontroller family (like Atmel devices) with all it's advantages, but also disadvantages, is not required, and hard/software compatible applications can still be expected in the next years.

from the uCapps site concerning the core module.

[jimh54]

I see that I have not asked the correct question. The bottom line question is; can I use the latest processor as a substitute for most, if not all, of the projects? They are pin compatible but are the internal differences enough to cause concern? The Microchip website says specifically NOT to use the PIC18F452 for current or future projects. That indicates to me they are likely to discontinue it. Are the differences in the newer ones significant enough to matter? Since the price difference is small, I would rather use the most capable one. That would be the PIC18F4685.

Thanks for all of the most polite and patient responses.

[nILS]

MIDIbox SID V2: still needs a PIC18F4685 because of the CAN interface and bigger flash memory (96k), but less RAM as the PIC18F4620. PIC18F4685 is not fully SW compatible to PIC18F452, therefore other applications could crash

MIDIbox FM: MBFM V2 is planned for far future (probably not this year). CAN support for linking MBFM with "slaves", or controlling MBFM from MBSID control surface can be expected. MBFM V1 firmware is running fine on PIC18F4685

all other MIDIbox firmwares are compatible to PIC18F452 and PIC18F4620. The usage of PIC18F4620 is recommented if you don't want to miss new features.

All info is from here: http://www.midibox.org/forum/index.php/topic,10951.msg84718.html#msg84718

[buhler]

TK says the firmware (MBFM v.1) is running "fine" on the 18F4685 but everywhere else i have looked the MBFM is linked to the 18F452....?  i could be wrong (most likely) but isn't that what's recommended?  ???

[ilmenator]

TK says the firmware (MBFM v.1) is running "fine" on the 18F4685 but everywhere else i have looked the MBFM is linked to the 18F452....?  i could be wrong (most likely) but isn't that what's recommended?  ???

I guess that's called progression.

What exactly don't you understand? The project was originally developed for the 452, so all documentation refers to that processor. It also runs fine on 4685. There will eventually be a new software version with new features that requires the 4685 to work properly. That's in the future, so the documentation does not include this yet. If you don't want to exchange the PIC when v2 comes out, you can already use the 4685 now for the v1.

I hope this makes it even more clear!  :)

Best regards, ilmenator

[buhler]

yes!  much clearer!  i just didn't want to misinform the O.P. ;D

[Imp]

I can confirm that the fm works on a pic18f685,

but i had to treat it as if it were a pic18f452:

I uploaded the mios file which is meant for the '452 and wired the LCD in 8bit-mode,

before i did this,  the mbfm_interconnection_test gave out strange voltages on D0, D1,D2 and D3.

Therefore the testtone and the fm-app itself didn't produce any sound, as the opl was not controlled properly.

I haven't tested if everything works as on a '452, because i have neither a bankstick, nor a CS...but the Lcd works and the  Rhodes is playing  8)