mc68hc912dg128 Freescale Semiconductor, Inc, mc68hc912dg128 Datasheet - Page 337

• Manufacturer Part Number: mc68hc912dg128
• Description: M68hc12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

17.12.4 Data Segment Registers (DSRn)
17.12.5 Transmit Buffer Priority Registers (TBPR)
MC68HC912DG128 — Rev 3.0
MOTOROLA
1. x is 5, 6, or 7 depending on which buffer Tx0, Tx1, or Tx2 respectively.
TBPR
$01xD
RESET
(1)
W
R
NOTE:
PRIO7
BIT 7
-
The eight data segment registers contain the data to be transmitted or
being received. The number of bytes to be transmitted or being received
is determined by the data length code in the corresponding DLR.
PRIO7 – PRIO0 — Local Priority
To ensure data integrity, no registers of the transmit buffers shall be
written while the associated TXE flag is cleared.
To ensure data integrity, no registers of the receive buffer shall be read
while the RXF flag is cleared.
PRIO6
BIT 6
Freescale Semiconductor, Inc.
This field defines the local priority of the associated message buffer.
The local priority is used for the internal prioritisation process of the
msCAN12 and is defined to be highest for the smallest binary number.
The msCAN12 implements the following internal prioritisation
mechanism:
•
•
•
-
For More Information On This Product,
All transmission buffers with a cleared TXE flag participate in the
prioritisation immediately before the SOF (Start of Frame) is sent.
The transmission buffer with the lowest local priority field wins the
prioritisation.
In cases of more than one buffer having the same lowest priority,
the message buffer with the lower index number wins.
PRIO5
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BIT 5
-
MSCAN Controller
PRIO4
BIT 4
-
PRIO3
BIT 3
-
Programmer’s Model of Message Storage
PRIO2
BIT 2
-
PRIO1
BIT 1
MSCAN Controller
-
Technical Data
PRIO0
BIT 0
-
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