Civil Engineering Reference
In-Depth Information
red. Consequently, all settings are well defined to start up values. There is no need
to clear any memory with software. The completion of the initialization process is
indicated by a flag.
The sleep mode disables the channels' clocking in order to save power effectively.
Reset Mode
In this mode, the configuration can be changed. Global reconfiguration
covers the definition of the memory usage and global behaviour, such as setting the
AFL.
Within the channels, the reset mode allows users to set communication parameters
such as bit timing.
Operation Mode
A channel can be put into operation mode if this mode has already
been set globally. At this point, the CAN channel starts its communication on the
CAN bus.
3.3.2.2
Test Modes
Within the operation mode of a channel, several test modes are available besides
regular operation.
Listen-Only Mode
All transmit functionality is disabled. This is also effective for
the
bus acknowledgement
and
error/overload reporting
on the CAN bus by the
transfer layer. The CAN channel behaves as a listener on the CAN bus, but it cannot
be seen by other bus participants. It is possible to use this mode to detect a valid
baud rate among a known selection.
Self-Test Modes
RS-CAN distinguishes between external and internal loops within
the self-test modes. In general, the self-test modes are used to verify the functiona-
lity and safety of the RS-CAN with software.
The internal loop modes allow internal communication to enable internal trans-
mitted messages to be received either in the same channel (using emulated
bus
acknowledgement
) or by other internal channels. In internal loop mode, the CAN
transceiver is not included, and the test messages are invisible for the other CAN
bus participants.
In external loop mode, the CAN transceiver is also included in the test loop.
In all self-test modes, the transfer layer is fully included in the test path.
3.3.3
Transmission of Messages
RS-CAN includes four methods of sending messages: the classical use of message
buffers, sending from a transmit queue, streamed sending through a FIFO, and auto-
