MC68HC908AS60ACFN FREESCALE [Freescale Semiconductor, Inc], MC68HC908AS60ACFN Datasheet - Page 361

• Manufacturer Part Number: MC68HC908AS60ACFN
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

27.6.4 BDLC State Vector Register
This register is provided to substantially decrease the CPU overhead associated with servicing interrupts
while under operation of a multiplex protocol. It provides an index offset that is directly related to the
BDLC’s current state, which can be used with a user-supplied jump table to rapidly enter an interrupt
service routine. This eliminates the need for the user to maintain a duplicate state machine in software.
I0, I1, I2, and I3 — Interrupt Source Bits
Bits I0, I1, I2, and I3 are cleared by a read of the BSVR except when the BDLC data register needs
servicing (RDRF, RXIFR, or TDRE conditions). RXIFR and RDRF can be cleared only by a read of the
BSVR followed by a read of the BDLC data register (BDR). TDRE can either be cleared by a read of the
BSVR followed by a write to the BDLC BDR or by setting the TEOD bit in BCR2.
Freescale Semiconductor
These bits indicate the source of the interrupt request that currently is pending. The encoding of these
bits are listed in
Address:
BSVR
$0C
$1C
$00
$04
$08
$10
$14
$18
$20
Reset:
Read:
Write:
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
Table
I3
0
0
0
0
0
0
0
0
1
$003E
Bit 7
R
R
0
0
Figure 27-19. BDLC State Vector Register (BSVR)
27-5.
I2
0
0
0
0
1
1
1
1
0
= Reserved
I1
0
0
1
1
0
0
1
1
0
Table 27-5. BDLC Interrupt Sources
R
6
0
0
I0
0
1
0
1
0
1
0
1
0
Cyclical Redundancy Check (CRC) Error
I3
R
BDLC Tx Data Register Empty (TDRE)
5
0
BDLC Rx Data Register Full (RDRF)
Symbol Invalid or Out of Range
Received IFR Byte (RXIFR)
No Interrupts Pending
Loss of Arbitration
Interrupt Source
I2
R
4
0
Received EOF
Wakeup
I1
R
3
0
I0
R
2
0
R
1
0
0
8 (Highest)
0 (Lowest)
Priority
1
2
3
4
5
6
7
BDLC CPU Interface
Bit 0
R
0
0
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