4.1. Obtaining Information about the Infrared Port in Laptops

4.1.1. SIR

Up to 115.200bps, the infrared port emulates a serial port like the 16550A UART. This will be detected by the kernel serial driver at boot time, or when you load the serial module. If infrared support is enabled in the BIOS, for most laptops you will get a kernel message like:

Serial driver version 4.25 with no serial options enabled
ttyS00 at 0x03f8 (irq = 4) is a 16550A     #first serial port /dev/ttyS0
ttyS01 at 0x3000 (irq = 10) is a 16550A    #e.g. infrared port
ttyS02 at 0x0300 (irq = 3) is a 16550A     #e.g. PCMCIA modem port

4.1.2. FIR

If you want to use up to 4Mbps, your machine has to be equipped with a certain FIR chip. You need a certain Linux/IrDA driver to support this chip. Therefore you need exact information about the FIR chip. You may get this information in one of the following ways:

1. Read the specification of the machine, though it is very rare that you will find enough and reliable information there.

2. Try to find out whether the FIR chip is a PCI device. Do a cat /proc/pci . The appropriate files for 2.2.x kernels are in /proc/bus/pci . Though often the PCI information is incomplete. You may find the latest information about PCI devices and vendor numbers in the kernel documentation usually in /usr/src/linux/Documentation or at the page of Craig Hart http://members.hyperlink.net.au/~chart . From kernel 2.1.82 on, you may use lspci from the pci-utils package, too.

3. Use the DOS tool CTPCI330.EXE provided in ZIP format by the German computer magazine CT ftp://www.heise.de/pub/ct/ctsi/ctpci330.zip. The information provided by this program is sometimes better than that provided by the Linux tools.

4. Try to get information about Plug-and-Play (PnP) devices. Though I didn't use them for this purpose yet, the isapnp tools, could be useful.

5. If you have installed the Linux/IrDA® software load the FIR modules and watch the output of dmesg, whether FIR is detected or not.

6. Another way how to figure it out explained by Thomas Davis (modified by WH): "Dig through the FTP site of the vendor, find the Windows9x FIR drivers, and they have (for a SMC chip):

   -rw-rw-r-- 1 ratbert ratbert 743 Apr 3 1997 smcirlap.inf -rw-rw-r-- 1 ratbert ratbert 17021 Mar 24 1997 smcirlap.vxd -rw-rw-r-- 1 ratbert ratbert 1903 Jul 18 1997 smcser.inf -rw-rw-r-- 1 ratbert ratbert 31350 Jun 7 1997 smcser.vxd

   If in doubt, always look for the .inf/.vxd drivers for Windows95. Windows95 doesn't ship with _ANY_ FIR drivers. (they are all third party, mostly from Counterpoint, who was assimilated by ESI)."

7. Also Thomas Davis found a package of small DOS utilities made by SMC. Look at http://www.smsc.com/ftppub/chips/appnote/ir_utils.zip . The package contains FINDCHIP.EXE. And includes a FIRSETUP.EXE utility that is supposed to be able to set all values except the chip address. Furthermore it contains BIOSDUMP.EXE, which produces this output:

   Example 1 (from a COMPAQ Armada 1592DT)

   In current devNode: Size = 78 Handle = 14 ID = 0x1105D041 = 'PNP0511' -- Generic IrDA SIR Types: Base = 0x07, Sub = 0x00, Interface = 0x02 Comm. Device, RS-232, 16550-compatible Attribute = 0x80 CAN be disabled CAN be configured BOTH Static & Dynamic configuration Allocated Resource Descriptor Block TAG's: TAG=0x47, Length=7 I/O Tag, 16-bit Decode Min=0x03E8, Max=0x03E8 Align=0x00, Range=0x08 TAG=0x22, Length=2 IRQ Tag, Mask=0x0010 TAG=0x79, Length=1 END Tag, Data=0x2F

   Result 1:

   Irq Tag, Mask (bit mapped - ) = 0x0010 = 0000 0000 0000 0001 0000 so, it's IRQ 4. (start at 0, count up ..), so this is a SIR only device, at IRQ=4, IO=x03e8.

   Example 2 (from an unknown machine)

   In current devNode: Size = 529 Handle = 14 ID = 0x10F0A34D = 'SMCF010' -- SMC IrCC Types: Base = 0x07, Sub = 0x00, Interface = 0x02 Comm. Device, RS-232, 16550-compatible Attribute = 0x80 CAN be disabled CAN be configured BOTH Static & Dynamic configuration Allocated Resource Descriptor Block TAG's: TAG=0x47, Length=7 I/O Tag, 16-bit Decode Min=0x02F8, Max=0x02F8 Align=0x00, Range=0x08 TAG=0x22, Length=2 IRQ Tag, Mask=0x0008 TAG=0x47, Length=7 I/O Tag, 16-bit Decode Min=0x02E8, Max=0x02E8 Align=0x00, Range=0x08 TAG=0x2A, Length=2 DMA Tag, Mask=0x02, Info=0x08 TAG=0x79, Length=1 END Tag, Data=0x00

   Result 2:

   a) it's a SMC IrCC chip

   b) one portion is at 0x02f8, has an io-extent of 8 bytes; irq = 3

   c) another portion is at 0x02e8, io-extent of 8 bytes; dma = 1 (0x02 =0000 0010)

   Thomas Davis has placed some device information at http://www.jps.net/tadavis/irda/devids.txt .

   Warning

   The package is not intended for the end user, and some of the utilities could be harmful. The only documentation in the package is in Microsoft Word format. Linux users may read this with catdoc, available at http://www.fe.msk.ru/~vitus/catdoc/ .

8. Use the Device Manager of the MicroSoft Windows9x/NT operating system.

9. You may also use the hardware surveys mentioned below.

10. And as a last ressort, you may even open the laptop and look at the writings at the chipsets itselfs. Here is an probably incomplete list of manufacturers: Chrystal, Hewlett Packard (HP, chipsets are marked HSDL), Hitachi, IBM, National Semi Conductor (NSC), NEC, Philips, Sharp, Standard Micro Systems Corporation (SMC/SMSC), Texas Instruments (TI), VLSI, Winbond. As an example of application circuits the HSDL-7001 (from a HP brochure, modified by WH):

    LEDs Encode/Decode SIR/FIR HSDL-1001 HSDL-7001 UART 16550/ MicroController ______ ______________ ____________ | | | | | | (|| TXD|<---|IR_TXD TXD|<---|SOUT | | | | | | | | | | RCV|--->|SIN | | | | | | | (|| RCV|--->|IR_RCV 16XCLK|<---|BAUDOUT | | | | NRST|-+ | | ------ -------------- | ------------ V