Crystal 12000 kHz (12-HC49U-S0,44 €) [You remember that fundamental crystals are measured in kHz?]
Serial EEPROM (EE 24LC64 SM0,92 €)
USB receptacle (USB BG0,29 €)
USB cord (AK 672/2-1,00,55 €) 1 m, or longer who need
SubD female connector 25 pin (D-SUB BU 250,10 €)
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 9380,30 €) 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.Populated PCB, ready to run
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.
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Ultimate source is mostly outdated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.
