[sdiy] dsPIC33 question..

Andre Majorel aym-htnys at teaser.fr
Thu Nov 13 10:04:39 CET 2008


On 2008-11-12 14:33 +0000, Seb Francis wrote:
> Tom Wiltshire wrote:
>> On 2008-11-12 03:01 +0000, Seb Francis wrote:
>>
>>> Unlike the 4xD it will have no MIDI, no display and no
>>> settings memory. Instead it will be fully controlled by lots
>>> of CV and on/off (gate) inputs.  Either external inputs and/or
>>> panel controls can be used as necessary ... pots for CVs,
>>> switches or buttons for on/off inputs. So this is something
>>> that will sit in a modular synth.

That's pretty much what I hoped to hack the 4xD into, so good
news.

> I'm wondering about MIDI input as well .. I wasn't planning to
> use it myself as I like the immediacy of the unit responding
> exactly to where the knobs and switches are set and to what
> external voltages are coming in.  But the dsPICs have UART built
> in and it wouldn't take much board space to add an opto-isolator
> and a couple of resistors (although not sure opto-isolators come
> in tiny packages... might have to be DIP).
>
> So what's the thoughts out there?  Is a MIDI input option worth
> having?

In the context of a modular, seems to me that CV and gates could
replace clock and note on/off messages... At first sight, MIDI
wouldn't be as useful as having, say, DC-coupled outputs.

But nothing stops you from laying tracks for a DIP 6N138 and
letting users who want MIDI install it themselves.

>> Definitely stick a ICSP socket on it. My programmer uses RJ11
>> plugs to connect between the programmer and various ZIF sockets
>> for different uPs. Consequently, I've started putting RJ11
>> programming sockets on my projects. The plugs cost more than a
>> simple 6-pin header, but it's much easier to plug in and out.
>
> Yeah, and plus the normal PCB headers have a relatively low
> number of connects and disconnects before the contacts stop
> being so springy.  Not sure about RJ11 though as I haven't seen
> any panel mount sockets and I don't want to tie the PCB to a
> particular panel layout by using PCB mount panel components.

Amphenol, Bulgin and Woodhead make panel-mount modular sockets.
Farnell and RS carry them. All those I've seen are 1) RJ45 and 2)
IP67 and accordingly bulky and expensive.

Farnell 116-6679 (Bulgin PX0839/PC) is relatively cheap at "just"
6.62 EUR but an RJ11 plug won't fit an RJ45 receptacle (I've tried).

-- 
André Majorel <URL:http://www.teaser.fr/~amajorel/>



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