M16CSLASH1N datasheet(162/238 Pages) RENESAS

162 / 238 page

Rev.1.00

Oct 20, 2004

page 150 of 222

M16C/1N Group

16. CAN Module

REJ09B0007-0100Z

16.10 Return from Bus off Function

When the protocol controller enters bus off state, it is possible to make it forced return from bus off state

by the return from bus off function of the C0CTLR register. At this time, the error state changes from bus

off state to error active state. Implementation of this function initializes the protocol controller. However,

registers of the CAN module such as C0CONR register and the content of each slot are not initialized.

16.11 Listen-Only Mode

When the RXOnly bit of the C0CTLR register is set to "1", the module enters listen-only mode.

Listen-only mode is not allowed to have any influence on the bus. It shall not send any frames nor send

acknowledgement, error frames, overload frames. When setting the CAN module to Listen-only mode, do

not request a transmission.

16.9 Basic CAN Mode

When the BasicCAN bit in the C0CTLR register is set to "1", slots 14 and 15 correspond to Basic CAN

mode. In normal operation mode, each slot can handle only one type message at a time, either a data

frame or a remote frame by setting C0MCTLi register (i = 0 to 15). However, in Basic CAN mode, slots 14

and 15 can receive both types of message at the same time.

When slots 14 and 15 are defined as reception slots in Basic CAN mode, received messages are stored

in slots 14 and 15 alternately.

Which type of message has been received can be checked by the RemActive bit in the C0MCTLi register.

Figure 16.23 shows the operation of slots 14 and 15 in Basic CAN mode.

Figure 16.23 Operation of Slots 14 and 15 in Basic CAN Mode

When using Basic CAN mode, note the following points.

(1) Setting of Basic CAN mode has to be done in CAN reset/initialization mode.

(2) Select the same ID for slots 14 and 15. Also, setting of the C0LMAR and C0LMBR registers has to

be the same.

(3) Define slots 14 and 15 as reception slot only.

(4) There is no protection available against message overwrite. A message can be overwritten by a

new message.

(5) Slots 0 to 13 can be used in the same way as in normal CAN operation mode.

Slot 14

Slot 15

Msg. n

Msg. n+2

Msg. n+1

Empty

Locked (empty)

Msg. n

Locked (Msg. n)

Msg. n + 1

Msg. n+2 (Msg. n lost)

Locked (Msg. n+1)

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