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Links

All communication implementations are centered around resources called links. Internally, links are mostly constituted of:

• A context; see Contexts for more information;

• A platform-specific transport implementation;

• A protocol, which is a set of resources and functions that do not constitute an interface, since protocols may obey different logics.

Links are opened using one of the following functions:

• cahute_open_simple_usb_link();

• cahute_open_usb_link();

• cahute_open_serial_link().

Note

The internal behaviour of these methods is documented in Opening behaviours.

USB device names

On detection or opening a link to a USB device, the name or path depends on the platform:

• On platforms using libusb, including Linux distributions and macOS, OS X, it represents the bus and address numbers in decimal separated by :, e.g. 001:014.

• On Win32, it represents the device path, such as USB\VID_07CF&PID_6101\6&1ff8b909&0&9 or USB\VID_07CF&PID_6102\0000uJPLBWa1.

Generic links

While Cahute aims at implementing official and widespread community protocols, the portability of its transports can be appealing to developers implementing a custom, possibly program-specific protocol between a host and a CASIO calculator, notably for the host part.

Since Cahute does not expose transports publicly, it allows selecting a special kind of links called “generic links”, which allows the following functions to be used on such links:

• cahute_receive_on_link();

• cahute_send_on_link();

• cahute_set_serial_params_to_link().

The following methods can be used to open a generic link with Cahute:

• Call cahute_open_serial_link() with the CAHUTE_SERIAL_PROTOCOL_NONE protocol, for opening a generic link over a serial transport;

• Call cahute_open_simple_usb_link() or cahute_open_usb_link() with the CAHUTE_USB_NOPROTO flag, for opening a generic link to a USB device.

The following developer guides demonstrate how to open and use generic links using the aforementioned methods:

• Opening a generic link to a calculator connected by serial.