doc: Update api doc regarding eamuse readers and usage

doc/api.md

@@ -1,4 +1,5 @@
 # Bemanitools API
+
 Bemanitools introduces interfaces abstracting the IO hardware of many games. This is used to implement support for
 non-intended IO devices from simple keyboard support, standard gamecontrollers to custom IO boards or using real
 hardware with the games (e.g. support for real legacy hardware).
@@ -12,6 +13,9 @@ If you want to write an implementation for your own custom piece of hardware, ch
 sub-folder) in the source code (src.zip).
 
 ## Implementations
+
+### IO boards
+
 The following implementations are already shipped with BT5.
 
 * BeatStream
@@ -34,10 +38,33 @@ The following implementations are already shipped with BT5.
     * [sdvxio-bio2.dll](sdvxhook/sdvxio-bio2.md): BIO2 driver
     * [sdvxio-kfca.dll](sdvxhook/sdvxio-kfca.md): KFCA IO board driver
 
+### Eamuse readers
+
 Eamuse hardware support is implemented separately:
+
 * eamio.dll (default): Keyboard and joystick input
+* eamio-icca.dll: Slotted/wave pass readers, required for old games with magnetic stripe cards
+
+#### ICCA readers for IIDX and port config in device manager
+
+The COM port for the card readers needs to be configured correctly in device manager. Otherwise,
+communication with the readers will fail if the settings do not align with how the game or
+bemanitools wants to operate them.
+
+Use built-in ports on your mainboard if available but an external USB to serial port dongle also
+works. 
+
+* Assign `COM1` to the COM port the card readers are connected to.
+* Ensure that the following settings for the COM port you are going to use are 
+set
+  * BAUD rate 57600
+  * Data bits 8
+  * Parity None
+  * Stop bits 1
+  * Flow control None.
 
 ## Development notes
+
 A DEF file for geninput.dll is included. To convert the DEF into an import library suitable for use with Visual C++, run
 ```
 lib /machine:i386 /def:geninput.def