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IrDA Prototype Project
IrDA Prototype Project
UPDATED March 2002, September 2002
Some of the links change and are updated as possible.
The primary change in this document is the update regarding compatibility with Windows 98 -- see end of document. Compatibility testing with Windows2000 is in progress and I do not anticipate any problems. The circuit is a "generic" using the HP SIR or FIR protocol and IrCOMM. Most problems have been resolved by setting up the machine BIOS to recognize the built-in IrDA on the motherboard as a comm port.
The circuit described here is from the application notes for the Hewlett-Packard
(now Agilent) HSDL-1100 IrDA interface
component (IrDA transceiver HP HSDL-1100)Alternate link here. The application note PDF file is available from Hewlett-Packard. A design guide is also available from Agilent as a PDF. The HSDL-1100 component is available from Newark Electronics
in small quantities Part number 52F8672, www.newark.com, about $5-6 US. The HP HSDL-1000 is a now obsolete (circa 1995 origin) component that should be adaptable to the same use described.
The completed circuit shown is a working prototype, and a much neater project can be accomplished. The circuit values are shown with the application circuit. A sample circuit board mask (an effort has been made
to keep this actual size when printed) and the component layout
for the circuit board are shown below. The completed prototype, and the appearance installed on a 5 1/4 inch disk
slot cover is also shown. Please note that the HP module is quite small (about 0.8 inch), with 20 pins to the inch, and soldering
this component can be fairly difficult! How it works It turns out that IrDA
is not implemented merely by constructing a device that signals through an LED and receives input from an
infrared detector. The shaping of the pulses, and the timing, is dependent upon software. Serial adapters also
require an IrDA "stack" in the operating system, but do not depend upon BIOS functions or motherboard functions to work (they use an additional chip to translate 16550 serial Rx/Tx to the IrDA module: e.g. HSDL-7000). The adapter described
here attaches to the IrDA pinout from a "modern" motherboard (here, a Packard Bell 680, so how modern is that? 'Not Very!'
--Modern probably means "Pentium"),
and requires the BIOS setup to select "IrDA" for the serial port as well. See later information for the typical pinout
of a "modern" motherboard.
Please note that the HSDL-1100 has capability of 4MB/s communication through the RXD-B line, but this NOT
implemented here, since the Palm permits "serial" IrDA up to 115,200 Bps only. This is through the RXD-A port
of the HSDL-1100. I believe the HSDL-1000 is ONLY 115.2 Kbps, hence "obsolete".
The cable from the circuit board carries Vcc (positive voltage), Ground, TX (transmit), and RX (receive) signals.
These are the signals available from the motherboard IrDA, a "five pin" configuration, with one pin absent to
assure orientation of the connector (see table., bottom of page).
A "strain relief" made from excess component lead passed through two holes in the circuit board and around
the cable insulation can also be seen on the prototype. Cable length should be fairly short (about two feet in the
prototype).
The HSDL-1100 available from Newark in small quantity has the "right angle" configuration, which means the
IR path is parallel to the circuit board "horizon". This allows the board to be affixed to a disk bay cover by soldering
two nuts to the front of the board, and passing machine screws through the cover into the nuts. A small cutout in
the cover allows IR to pass to and from the IrDA transceiver. Different mounting would be required for a different
component configuration.
A substantial amount of circuit board space is used in the surrounding "ground", with a narrow strip for Vcc, and
enlarged pads for component soldering. I am not certain whether this much ground plane is necessary.
Once the adapter is constructed, and the system bios set to IrDA, a "stack", such as
the W95IR.EXE available from Microsoft, is run (Please don't quibble about whether this is really a "stack" - I'm using a casual description here). This assigns the IrDA serial to a new port and interrupt, which
on this machine is COM4: and LPT3:. It escapes me how LPT3: can be a serial port, but that is what it does.
Once this is setup, Palm Desktop HotSync recognizes the new serial port and allows the desktop to
communicate by IR. The Palm (here, a Palm III) needs the
Enhanced Infrared Update from 3Com, and under
preferences, IR instead of serial cradle is selected. IR HotSyncs can be done easily, perhaps somewhat more slowly (UPDATE - IrHotSync at 115200 under Win98).
The Pilot-XF program (also known as Pilot-Xfer - search under google for pilot-xfer for Win32 and other ports)
allows single PRC installs, lists of installed PRC/PBDs, and backups as well. Please see previous minutes
of the PUGSL user group
September, 1999,
October, 1999 (http://www.geocities.com/pug_stlouis) for some further detail (local copy of arsene's page -- PPP and IrDA Palm)
(arsene's page -- PPP and IrDA Palm).
This document describes construction of a working IrDA interface that allows infrared transfers and HotSyncs between Palm PDAs and desktop PCs running Windows95 with a m-o-d-e-r-n
motherboard.
| Component | Recommended Value | Notes |
| R1 | 560 Ohms, 5%, 1/8 watt | |
| R2 | 4.7 Ohms, 5%, 1/2 watt | lower power rating may be okay |
| R3 | 10 Ohms, 5%, 1/8 watt | 1 |
| CX1 | 0.47 microF, 10%, X7R Ceramic | 2, Mylar works for CX1,5,7 |
| CX2 | 220 pF, 10%, X7R Ceramic | |
| CX3 | 4700 pF, 10, X7R Ceramic | |
| CX4 | 0.010 microF, 10%, X7R Ceramic | |
| CX5 | 0.47 microF, 20%, X7R Ceramic, <5mm lead length | 2 |
| CX6 | 6.8 microF Tantalum, larger for noisy environment/supply | |
| CX7 | 0.47 microF, 20%, X7R Ceramic | 3, CX1,CX5,CX7 same values |
1) In environments with noisy supplies, rejection can be enhanced by including R3 as shown in application circuit.
2) CX1 and CX5 must be placed within 0.7 cm of the HSL-1100 to obtain optimal noise immunity.
3 Only necessary in applications where transmitter switching causes more than a 50 mV ripple on Vcc.
Application Circuit and Board Mask
Top and bottom view of completed circuit secured to drive bay cover.
| Pin | Name | Description |
| 1 | +5V | Power Vcc |
| 2 | "key" | Not Connected |
| 3 | IRRX | IR Module Data Received (RX) |
| 4 | GND | Ground |
| 5 | IRTX | IR Module Data Transmit (TX) |
UPDATES March 2002
The original installation of this circuit was in an OLD Packard Bell 680 with AMIBIOS 1.00.08.DN0R. That machine was and is running Win95, and I guess due to gross legacy affinity and nostalgia, I just haven't changed over to Win98 on that machine. I have another PB with Win98, but the AMIBIOS 1.00.07.DY0R just doesn't seem to allow me to set up IrDA -- and why bother with it. A third machine is set up with several OS's and was used for testing under Win98 (so far). Do not hold your breath waiting for me to try this with XP (although Jon Goss writes me that the adaptor works great under XP - thanks Jon). Win2000 should be added to this page soon see this page for an IrComm implementation of a virtual comm port for Win2000. The third machine is an AWARD bios PII-366 set up for multi-boot (Win98/Linux/Win2k). The five pin IrDA header is between ISA slots 1 and 2 and pin 1 is marked with an arrow. Pin two is NOT clipped off, unlike the PB machines.
The bios setup under "builtin peripherals" allowed me to disable serial ports A and B and enable the IrDA port with a choice of IRQs and mems -- I selected IRQ 4 and 3F8 (com1) for the IrDA. Win98 recognized the built-in IrDA from the board as *pnp0510 and automatically installs the necessary drivers and software from the Win98 SE CDROM. The "virtual com port" defaults to COM4, and the "virtual LPT" to LPT4.
The Palm Hotsync Manager setup is used to select COM4 as the port for HotSync.
This is how the Infrared Monitor (click on the IR icon in the taskbar or from the Control Panel) looks when you are successfully connected
