ST72561J9-Auto STMicroelectronics, ST72561J9-Auto Datasheet - Page 221

• Manufacturer Part Number: ST72561J9-Auto
• Description: 8-bit MCU for automotive
• Manufacturer: STMicroelectronics

Specifications of ST72561J9-Auto

• Hdflash Endurance: 100 cycles, data retention 20 years at 55 °C
• 5 Power Saving Modes: halt, auto wake up from halt, active halt, wait and slow

ST72561-Auto
17.4
17.4.1
/ remote frame) in loop back mode. In this mode, the beCAN performs an internal feedback
from its Tx output to its Rx input. The actual value of the CANRX input pin is disregarded by
the beCAN. The transmitted messages can be monitored on the CANTX pin.
Loop back combined with silent mode
It is also possible to combine loop back mode and silent mode by setting the LBKM and
SILM bits in the CDGR register. This mode can be used for a “Hot Selftest”, meaning the
beCAN can be tested like in loop back mode but without affecting a running CAN system
connected to the CANTX and CANRX pins. In this mode, the CANRX pin is disconnected
from the beCAN and the CANTX pin is held recessive.
Figure 99. beCAN in combined mode
Functional description
Transmission handling
In order to transmit a message, the application must select one empty transmit mailbox, set
up the identifier, the data length code (DLC) and the data before requesting the transmission
by setting the corresponding TXRQ bit in the MCSR register. Once the mailbox has left
empty state, the software no longer has write access to the mailbox registers. Immediately
after the TXRQ bit has been set, the mailbox enters pending state and waits to become the
highest priority mailbox, see Transmit Priority. As soon as the mailbox has the highest
priority it will be scheduled for transmission. The transmission of the message of the
scheduled mailbox will start (enter transmit state) when the CAN bus becomes idle. Once
the mailbox has been successfully transmitted, it will become empty again. The hardware
indicates a successful transmission by setting the RQCP and TXOK bits in the MCSR and
CTSR registers.
If the transmission fails, the cause is indicated by the ALST bit in the MCSR register in case
of an Arbitration Lost, and/or the TERR bit, in case of transmission error detection.
Transmit priority
By identifier:
when more than one transmit mailbox is pending, the transmission order is given by the
identifier of the message stored in the mailbox. The message with the lowest identifier value
has the highest priority according to the arbitration of the CAN protocol. If the identifier
values are equal, the lower mailbox number will be scheduled first.
Doc ID 12370 Rev 8
beCAN
CANTX CANRX
Tx
=1
Rx
beCAN controller (beCAN)
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