Stable Controller IDs¶
By default, MAME does not assign stable numbers to input devices. For instance, a game pad controller may be assigned to “Joy 1” initially, but after restarting, the same game pad may be reassigned to “Joy 3”.
The reason is that MAME assigns numbers to input devices in the based on enumeration order. Factors that can cause this to change include disconnecting and reconnecting USB or Bluetooth devices, changing ports/hubs, and even just restarting the computer. Input device numbers can be quite unpredictable.
This is where the mapdevice configuration setting comes into the picture.
By adding this setting to a controller configuration file, you
can ensure that a given input device is always assigned the same number in MAME.
Using mapdevice¶
The mapdevice XML element is added to the input XML element in the
controller configuration file. It requires two attributes, device and
controller. Note that mapdevice elements only take effect in the
controller configuration file (set using the -ctrlr option) – they are ignored in system configuration files and
the default configuration file.
The device attribute specifies the device ID of the input device to match.
It may also be a substring of the device ID. To obtain the device ID for an
input device, select it in the Input Devices menu, and then select Copy
Device ID. The device ID will be copied to the clipboard. You can also see
input device IDs by turning on verbose logging (more on this later). The format
of device IDs depends the type of device, selected input provider module and
operating system. Your input device IDs may look very different to the examples
here.
The controller attribute specifies the input token for the input device type
(i.e. JOYCODE, GUNCODE, MOUSECODE) and number to assign to the
device, separated by an underscore. Numbering starts from 1. For example the
token for the first joystick device will be JOYCODE_1, the second will be
JOYCODE_2, and so on.
Example¶
Here’s an example:
In the above example, we have four device mappings specified:
The first two
mapdeviceelements map player 1 and 2 light guns to Gun 1 and Gun 2, respectively. We use a substring of the full device IDs to match each devices. Note that, since this is XML, we needed to escape the ampersands (&) as&.The last two
mapdeviceselements map player 1 and player 2 gamepad controllers to Joy 1 and Joy 2, respectively. In this case, these are XInput game controllers.
Listing Available Devices¶
There are two ways to obtain device IDs: by copying them from the Input Devices menu, or by turning on verbose logging and finding the messages logged when input devices are added.
To reach the Input Devices menu from the system selection menu, select General Settings, and the select Input Devices. To reach the input devices menu from the main menu, select Input Settings, then select Input Devices. From the Input Devices menu, select a device, then select Copy Device ID to copy its device ID to the clipboard.
To use verbose logging, run MAME with the -v or -verbose option on the
command line. Search the output for messages starting with “Input: Adding…”
that show recognised input devices and their respective IDs.
Here an example:
Furthermore, when devices are reassigned using mapdevice elements in the
controller configuration file, you’ll see that in the verbose log output, too,
such as:
Limitations¶
You can only assign stable numbers to devices if MAME receives stable, unique device IDs from the input device provider and operating system. This is not always the case. For example the SDL joystick provider is not capable of providing unique IDs for many USB game controllers.
If not all configured devices are connected when MAME starts, the devices that are connected may not be numbered as expected.