New Project wp34s micro usb flash cable revisited

[BarryMead]

(02-08-2015 08:42 PM)MarkHaysHarris777 Wrote:  It would be nice to see Harald's schematic, and have a bit of a theory of operation on the board from his perspective; I'd like to know his thoughts (that might have existed at one time, but I have not seen it). Thanks for reverse engineering the board from the photo! I had not tried to do that yet, although I have seen the photo too... I'd like to play with the board a bit; but I'm still inclined to use the board in the FTDI adapter, if I do that at all. Barry's three wire design with a small phone jack is a very simple tempting idea.

I ordered one of Harald's USB boards, and modified one of my calculators that way.
From my experience here are the PROS/CONS of Harald's board vs 2.5mm Headphone jack method.

ADVANTAGES TO HARALD'S BOARD:
1. Inexpensive link cable (standard USB to micro-USB)
2. Includes IR link to printer for those who own a printer.
3. Better ESD protection as standard USB inputs are designed for external connections.
4. While USB cable is connected 3V power is supplied by USB port no drain on Coin Cells.
This can make flashing more reliable as you never have to worry about your coin cells going dead
during a flashing cycle.

ADVANTAGES TO 2.5MM HEADPHONE JACK:
1. Less wiring (only 3 wires) (Harald's USB board requires 6 to 7 wires)
2. Simpler case modifications (No cutting on the case mounting struts)
3. No removal of surface mount Inductors LB1 and LB2 required.
4. Direct Calculator to Calculator transfer of Programs and Data is possible.

I hope this helps you make your decision, Barry