Deutscher Originaltext
Parallel to USB Converter “LPTzUSB”
A description for do-it-yourself; Device available
(30€, please email)
Photo of complete device. The green LED shows the USB connection status;
the red LED the power status
This (no more unique) device
enables connecting of a
USB printer to an old-style parallel port.
LPTzUSB
kann be attached either directly or with an extension cable to computer's
printer port. (LPTzUSB has a 25-pin SubD male connector).
On the other face of LPTzUSB, a standard USB cable has to be connected
to the printer (LPTzUSB has a 4-pin USB-A socket).
The Host Controller used supports USB Full-Speed (12 Mbit/s)
and Low-Speed (1,5 Mbit/s) but not High-Speed (480 Mbit/s).
The use of an external AC/DC adaptor is highly recommended.
It must supply 5 V and at least 50 mA.
USB hubs between LPTzUSB and printer are currently not supported.
However, multi-function devices (with scanners, card readers, etc.)
are supported, but only for printing.
Recommended for connecting USB printers to:
- Windows95 systems (or older)
There must exist an appropriate printer driver
for the desired operating system!
Or the printer must support a common language like
PostScript, PCL, ESC/P or Text-Only
- older PCs or laptops/notebooks
There are IMHO no ISA USB cards around
- Parallel Printer Switch Boxes (2 PCs at 1 printer or similar)
You may combine with
USB to Parallel Converters too!
- Pocket databases, ancient computers (Apple Classic, C64, Amiga, Atari…)
- Bureau machines, cash stations, store-managing systems
- Tool machines (e.g. for a protocol printer)
Not recommended for:
- Computers with PCI slots should be upgraded with (cheap)
USB cards
- Something else than printers.
USB memory will be supported in the future,
LPTzUSB will then simulate a remote computer for Total Commander.
- USB dongles (software protection devices) cannot be supported ever!
- DOS software that runs in a Windows' DOS box and will print to an LPT:
Here, a software-only solution is much better that redirects output to USB.
(VDD in preparation)
Successor model:
A successor of the device described below is in preparation using
PIC32MX420 microcontroller.
This will break the 30 kByte/s data transfer rate of the current design,
and is even cheaper.
Use as development kit:
Because this converter contains a well-known microcontroller
ATmega16 and a „bidirectional“ USB Host+Device controller,
an enthusiastic programmer can make very different things.
For example, a USB mouse to serial or PS/2 converter,
a USB keyboard to DIN or PS/2 converter, a copy device
from a USB scanner or digital camera to a USB printer (via Hub) etc.
Making the device
I have used professional PCBs. All production data is available
in Eagle (a German PCB CAD software) format.
For minimizing effort for reflow process, all SMDs are on one side only.
Parts list / Bill Of Materials
| USB Host/Device controller SL811HST-AC | 428-1464-ND | 6,74+
|
| Voltage regulator TPS76133 | 296-11010-1-ND | 0,89+
|
| Voltage regulator | µA78L05 | 0,12
|
| MCU ATmega16 | ATMEGA 16-16 TQ | 2,55
|
| Crystal 12000 kHz | 12,0000-HC49U-S | 0,23
|
| SubD male plug 25-pin | D-SUB ST 25 | 0,10
|
| LED red + LED green | LED 3mm rt | 0,05
|
| LED 3mm gn | 0,05
|
| USB socket Type A | USB AW | 0,20
|
| Hollow socket | HEBW 21 | 0,26
|
| „Infantry“ | PCC2233CT-ND | 0,156+ *2
|
| X7R-G0603 100n | 0,05 *2
|
| NPO-G0603 22p | 0,05 *2
|
| BCN16 22k | 0,02
|
| BCN16 22 | 0,02
|
| SMD-0805 2k2 | 0,08 *2
|
| BAT 54C | 0,07
|
| 1N4148SMD | 0,04
|
| Housing | COM 938 | 0,30
|
| PCB | ul-11.brd | 5,00
|
| USB cable | AK 672/2-2,0 | 0,60
|
Component placement
SMD components and crystal are placed as usual.
Known from USB2LPT there are two sockets that
will be placed as edge-mount devices although not suited for.
The SubD plug can be easily mounted in edge-mount technology.
Housing: Don't forget the holes for LEDs and the labels.
The PCB inside.
(For former release click here.)
All SMDs are reflow-friendly on one side only
Programming
Programming of ATmega16 will be done with AC/DC converter and a special
parallel-port adapter
directly at the parallel port, e.g. with PonyProg2000.
The RESET connection will be done via internal solder bridge SJ2.
This bridge must be closed for programming
and may remain closed for operating the device.
All JTAG signals are fed to the SubD plug too (for programming and/or debugging),
but I've not used these pins anymore.
The PonyProg2000 configuration bits must be set as shown in the following picture:
configuration bits: Please set accordingly!
Software
Usage
- Original device
-
An AC/DC adaptor with regulated output voltage 5 V
is highly recommended!
The device is protected against wrong polarization but not against overvoltage!
- Rev.1 (after 2007)
-
An AC/DC adaptor with at least 8 V output voltage is necessary.
Non-regulated output is sufficient.
For running of LPTzUSB, a RS232 to TTL converter is recommended too.
So you can observe data transmission and other useful things,
e.g. using HyperTerminal at 38400 Baud. See following picture:
LPTzUSB status via serial „debug terminal“
Note that the ATmega16 program instructs HyperTerminal to draws the
colored picture. There is no special Windows program necessary for nice output.
The bytes of descriptors shown have following meaning:
- USB address (without HUB always 01)
- USB device class (printer: 07)
- USB device subclass
- USB protocol
- Number of Configuration (mostly 01)
- Number of Interface (mostly 00)
- Number of Alternate Setting (mostly 00)
- Number of Endpoints (not counting EP0)
- EP0: Bits:
- 7: Direction (1=IN) [Not valid for EP0]
- 6: Toggle
- 5-4: Transfer type, 00=Control, 01=ISO, 10=Bulk, 11=Interrupt
- 3-0: Endpoint Number
- EP0: FIFO size
- EPx: Bits for next Endpoint etc.
- EPx: FIFO size for next Endpoint etc.
Delivery
Although this device requires an AC/DC adaptor, supplying this heavy device
outside Germany is not recommended!
Package. Think the AC/DC adaptor is not included.
Frequently Asked Questions
Why can I can't get such a device from my local computer store?
Such devices are not commonly useful:-)
Furthermore, you have the possibility to print to a file
and copy the .PRN file to a USB capable PC and print it out there.
Moreover, Ethernet to USB printer converters are widely available.
Making such a device is possible since one or two years(!)
Is there a high-speed version?
No. It's almost useless because data at parallel port is commonly much
slower than USB Full-Speed. And data must be transferred through the
microcontroller.
High-speed USB host controllers with microcontroller interface are
not known yet.
For Low-Speed there are much cheaper solutions around! Why bother?
There are no Low-Speed printers. Only mice and keyboards.
For Full-Speed simulation, all known microcontrollers are too slow.
What about the USB-ID (US$1500)?
Not necessary for host controllers.
A USB device that needs power – is that a bit brain-dead?
Attention: This is a USB host,
it must be able to supply other devices too!
Supplying power in reverse direction is never intended in the host-centric
USB specification.
Do I need a AC/DC adaptor?
Let's say: yes. Always.
You can watch the current voltage at HyperTerminal.
Can I clone this?
Yes. Only for assigning serial numbers I want feedback.
Henrik Haftmann,
Chemnitz, den 12. September 2006
of PCB,
Programming adaptor for PonyProg2000
