Infineon Technologies TC1728 User Manual page 1339

Table 20-5 Message Transmission Bit Definitions (cont'd)
Bit Description
TXEN1 Transmit Enable 1
This bit is used in transmit FIFOs to select the message object that is
transmit active within the FIFO structure.
For message objects that are not transmit FIFO elements, TXEN1 can
either be set permanently to 1 or can be used as a second independent
transmission enable bit.
RTSEL
When a message object has been identified to be transmitted next after transmission
acceptance filtering, bit MOCTRn.RTSEL (Receive/Transmit Selected) is set.
When the message object is copied into the internal transmit buffer, bit RTSEL is
checked, and the message is transmitted only if RTSEL = 1. After the successful
transmission of the message, bit RTSEL is checked again and the message
postprocessing is only executed if RTSEL = 1.
For a complete re-configuration of a valid message object, the following steps should be
executed:
1. Clear MSGVAL bit
2. Re-configure the message object while MSGVAL = 0
3. Clear RTSEL and set MSGVAL
Clearing of RTSEL ensures that the message object is disconnected from an
ongoing/scheduled transmission and no message object processing (copying message
to transmit buffer including clearing NEWDAT, clearing TXRQ, time stamp update,
message interrupt, etc.) within the old context of the object can occur after the message
object becomes valid again, but within a new context.
NEWDAT
When the contents of a message object have been transferred to the internal transmit
buffer of the CAN node, bit MOSTATn.NEWDAT (New Data) is cleared by hardware to
indicate that the transmit message object data is no longer new.
When the transmission of the frame is successful and NEWDAT is still cleared (if no new
data has been copied into the message object meanwhile), TXRQ (Transmit Request) is
cleared automatically by hardware.
If, however, the NEWDAT bit has been set again by the software (because a new frame
should be transmitted), TXRQ is not cleared to enable the transmission of the new data.
User's Manual
MultiCAN, V2.24
Controller Area Network Controller (MultiCAN)
20-46
TC1728
V1.0, 2011-12