MiniFTDI (a bad week)

A simple, actually not even worth mentioning, USB to CMOS level EIA-232 (RS-232) converter.
Includes Parallax-Propeller-Reset (aka.: Propeller-Clip).

A typical example of wasting invaluable development time for completely other stuff...

Until now, I included the FTDI in every Propeller based board, I created. This time, I needed something more "universal" (...) and detachable.
Two hours should have been enough. Something made it three days...

Lab's Law


  • created schematic, incl. library, within 1 hour (incl. 1 coffee)
  • created layout, within another hour (incl. 1 cold coffee)
  • hit 'save'
  • ***WHAM*** system off, lights out, a dog barks
  • circuit breaker...
  • found no fault but needed to detach all switching PSUs; 1 hour
  • next, a coffee; machine: "system fault, call service"
  • immediately disassembled the service friendly machine (triangular screw heads... idiots!); 2 hours
  • found fault 1 hour later; a thermal sensor decided to leave the brewing unit, dangling around
  • no problem, thermal adhesive is in the lumber-room
  • middle row, undermost box of 6, all stacked on each other (thanks, DYMO!)
  • 5 boxes on the floor, emptying themselves (do not trust paper, use tool-steel...)
  • 4 hours pick-and-sort
  • day gone...
  • no coffee; tea, fine; floor, child, toy-car, tea, floor getting nearer...;
  • at least, I was awake; cleaned up
  • forgot to take out adhesive off the box
  • middle row, undermost box of 6, all stacked on each other; success!
  • glue dried up
  • car, parking place, store, car, parking ticket; 1 hour
  • repaired machine, had coffee; 2 hours, but relaxing
  • back to layout, hit SAVE, success; 1 hour
  • turned on milling PC: "no operating system"; WHAT NEXT?
  • removed 2 others PC on top, disassembled the crap, refitted S-ATA cable with 2 min epoxy (suffer, suffer!)
  • turned on milling machine, *click* nothing
  • actually it WAS on, already; at least, I then knew why the circuit breaker triggered the day before...
  • not that heavy (70kg), but completely surrounded by other equipment, including the 3 PCs from before...
  • spent rest of the day repairing the machine (standard fault, switching PSU, electrolytic capacitors)
  • had coffee; nothing happened
  • milling PC and machine ON; nothing extraordinary happened
  • prepared machine, PCB, program, homing axes...
  • ***WHAM*** there went 45 bucks (EUR); a brand new LPKF RF 6mil end mill
  • forgot to attach the z axis home switch, that bad day #2, before
  • another mill, another try; success, but another two hours gone...
  • milled out board manually on another machine
  • cleaned that nasty, sticky FR4 above the bathroom sink
  • *plop* down the drain...
  • took off U-pipe, found PCB, matchbox car and a barrette
  • needed coffee... only 1l milk left? -> children built an "invisible" submarine; creative but annoying...
  • carefully, virtually trembling, soldered PCB
  • success; blackout


The layout was created for milling machines (and without solder resist):

  • one power connection was intentionally left out (avoids short circuits under USB plug)
  • all attached FTDI pins were made a little longer (easier soldering)
The four RS-232 pads (X1) were made for soldering on a 2.54mm header.

There is nothing more to say about this ... little thing.
Use the library/schematics/layout as a quick starting point for your own stuff...

the damn schematic
the f****** layout

NOTE 11/2010:
What can you do, if all your milled prototypes were stolen by software guys?
Right. You won't ever see them again (the prototypes =), make a series...

the (almost unchanged) schematic
a nicer, smaller layout

Useless Pics

three days after...

SPIF TORX-receiver on-board
a closer view
and the connections



- schematic (PDF)
- schematic (SCH)
- placement (PDF)
- layout (BRD)
DOWNLOAD: miniftdi V1 V1.0 (biiig and longer pads (for milling))
DOWNLOAD: miniftdi V2 V2.0 (smaller)

The driver can be downloaded, here.

ASkr 12/2009 initial (and forever lasting ;-) version
ASkr 11/2010 updated docs for smaller V20 version