Re: Home Grown ActionTec Development Daughterboard

Here are the parts and prices for what I would use.

$1.67  Intersil ICL3221CA -- 3.3V RS232 level converter
$3.12  TI TL16C550CIPT -- UART
$0.093 Fairchild Semi 74VC04M -- Hex inverter
$2.60  M-tron MHR13TAJ-1.8432 -- 1.8432Mhz crystal

$7.48 grand total

All parts are SMT.  All prices are from Arrow Electronics (www.arrow.com) for
single pieces.  The SMT crystal was showing no stock.  You could substiture the
leaded version (MP-1 1.8432MHZ) at a price of $1.18.

With the exception of the crystal I have the DIP versions of each of the above
for my testing on the breadboard.

Patrick M


--- "Bruce D. Lightner" <lightner-2huV/[email protected]> wrote:
> Scott,
> 
> > Say 50 people want one and we make a "group buy" of all the goodies.
> 
> I made up a Digikey parts list spreadsheet last night.  We have a system 
> that turns an Excel BOM spreadsheet into a Digikey automatic ordering Web 
> page.  I'll be puting it up on the "Wiki".
> 
> It looks like the parts are ~$22 in quantities of 10 (usually a Digikey 
> "price-break" point), plus ~$7 per PCB in groups of 9 from ExpressPCB 
> (which, with a simple layout change, could be 12 PCB's per ExpressPCB 
> "miniboard" fab run).
> 
> The 3.3V RS-232 converter is the biggest cost element at $5.63 each.  If 
> anyone knows a good cheaper alternative, I'd like to know.
> 
> Alternatively, the RS-232 "level shifting" can be done with a few 
> resistors and the left-over inverters in the 74AC04 hex inverter chip.  I 
> do this all the time.  However, you don't get true negative RS-232 signal 
> transistions this way.  Nevertheless, modern PC serial ports don't 
> care...0-3.3V signaling is fine with them!
> 
> We now just need a "groupie" to make a Digikey and ExpressPCB order and 
> distribute the parts! (Read *not me*!)
> 
> > It would be easier for end users if the layout changed slightly on the 
> > connectors, so for "revision 2" of the pcb I would like to make a 
> > friendly suggestion, armchair quarterback-style!  :-)
> 
> Better is the enemy of good enough! :-)
> 
> I got bored looking at all the possible I/O options, and made a "command 
> decision" to do what I did, and assumed that I'd either solder wires 
> point-to-point into the serial/reset/boot mode/USB connector holes, or I'd 
> put in a 12-pin 0.1" dual-row right-angle header and makeup cables with 
> mating plugs on the end...much like you see with PC motherboard connectors 
> to the "reset" switch, speaker, power switch, etc.
> 
> > If the pcb had a 10 pin (5x2) header for the serial port, then we could 
> > use off-the-shelf IDX to DB9 serial cables often used for taking a mobo 
> > serial header to a PC slot cover plate.  I have the proper mapping for 
> > this I can supply.
> 
> In my many years of using these serial port IDC ribbon cables, I've been 
> burned many times with the pinouts changing.  If here *really* is a 
> "standard" now, that may make sense...ignoring the fact that the PCB is 
> tiny and a 10-pin connector may be hard to fit.  (I guess the PCB can 
> always be made a bit longer.)
> 
> > Same idea for the USB header; 5 (or 6?) pin SIP.
> 
> Is there a standard for USB on PC motherboards?  Maybe there is and I 
> haven't paid attention.  When I'm building PC's "from scratch" at home, I 
> usually don't add the "front panel" USB wiring.  The last PCB case I got 
> had individual 1-pin connectors for each and every USB signal wire.  This 
> makes me think that every PC motherboard is different in this area!
> 
> > As well as a separate 2x2 header for the BOPT & reset switches.
> 
> In fact, that's the situation now.  The "headers" are just real close 
> together! :-)
> 
> > They could be soldered on as right angle so it all still fits inside the 
> > case.
> 
> That's my current plan...in fact I'm pretty sure you can solder the RA 
> dual-row 12-pin header to the underside of the PCB.
> 
> > Bottomline, if we slightly rearrange how many pins (a few extra), and 
> > how they are wired (some will be n/c), then it becomes plug-n-play for 
> > connection.
> 
> A laudable goal, let's fine tune it if and when this PCB works.  Your 
> feedback and ideas are welcome!
> 
> Best regards,
> 
> Bruce
> 
> -- 
>   Bruce D. Lightner
>   Lightner Engineering
>   La Jolla, California
>   Voice: +1-858-551-4011
>   FAX: +1-858-551-0777
>   Email: lightner-2huV/[email protected]
>   URL: http://www.lightner.net/lightner/bruce/
> 
> __
> ActionHack Mailing List - ActionHack-W7/[email protected]
> http://www.express.org/mailman/listinfo/actionhack
> http://www.embeddedlinuxinterfacing.com/wiki.php/ActiontecDualModem


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