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Links and mediums

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

• A context; see Contexts for more information.

• A medium, which is an interface with a set of resources to communicate with the underlying medium opened with the system or hardware.

• 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.

Generic links

While Cahute aims at implementing official and widespread community protocols, the portability of its link mediums 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 link mediums 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 medium;

• 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.