Converter From USB To Parallel

Electronic Components⚓

You need:

AN2131SC (the EZ-USB, 8,40 €)
Crystal 12000 kHz (12-HC49U-S 0,44 €) [You remember that fundamental crystals are measured in kHz?]
Serial EEPROM (EE 24LC64 SM 0,92 €)
USB receptacle (USB BG 0,29 €)
USB cord (AK 672/2-1,0 0,55 €) 1 m, or longer who need
SubD female connector 25 pin (D-SUB BU 25 0,10 €)
Transistor, Zener diode (0,13 €) as voltage regulator
Capacitors and Resistors (SMD 0805, about 1,50 €)
Double-sided PCB (see below) without chemical vias
Housing (COM 938 0,30 €) and cover sheet (FP4, make it by hand if necessary)

(Ordering numbers refer to German electronics distributor Reichelt and pricing for sept. 2004 in € in parentheses) A complete bill of material is contained in U.DOC.

Software⚓

Circuit Diagram (PostScript; you can get a PDF in landscape format)
The bit assignmend between microcontroller and SubD connector is intentionally chaotic to save vias and PCB space.
The jumper and both resistors 24 Ω are not required. The LED and R4 are optional.
PCB layout and silkscreen (PostScript; you can get a PDF)
The USB receptacle must be sold into the cutout. All fits into the housing.
The Ultimate sources are here.
Firmware for serial EEPROM
It simply puts USB OUT transfers to the OUT port, and answers to IN transfers. ECP are EPP are simulated too.
The driver for Windows you can get from page above, and usage hints too.

Known PCB bugs and inconveniences⚓

EEPROM shape too small, or
EEPROM should be connected to 5 V (cheaper and smaller type)
Cumbersome deactivation of EEPROM (for emergency)
Missing ground bridge on SubD Pin25 (Some customers want to use this pin to feed 5V to external device)
PCB too short for easy closing of housing at USB front
Ultimate source is mostly outdated

External downloads for production⚓

If you decide to build this device, you have to download a development kit for the AN2131 from Cypress. The data sheet is not necessary, but useful to understanding.

External downloads for modifications⚓

For recompilation you need ASEM51 und the complete Windows DDK ("Windows 98 DDK" preferred).

How to build⚓

At first you make the vias. Then all SMD components, then the thru-hole components. Three bigger components mus be bent to be flat, the crystal, maybe tantalum capacitor. The SubD connector comes to the edge of the PCB.

The USB “B” receptacle stays in the middle of the housing. Because there is no edge-mounting component available, this component is used instead and must be soldered at the left and right metal plate.

When you are complete, you test the circuit with "EZUSB Control Panel" from Cypress. (Windows should request a driver; you satisfy it by supplying the driver from the Cypress development kit.)

Programming⚓

With Cypress' “EZUSB Control Panel” you write the following firmware into the serial EEPROM. No programming device is needed!

Start "EZ-USB Control Panel" (EzMr.EXE) from start menu (installed by Cypress' development kit)
Press button
Give him the file
Stand by!! About 20 seconds.

While prototyping, it is sufficient to leave the serial EEPROM unprogrammed; you may even decide not to have an EEPROM at all.

Keywords: USB, LPT, parallel, parallel port, printer port, converter, adaptor
To USB2LPT — Overview

USB2LPT – Cloning instructions for Release 1.0