MC68HC912B32VFU8 Freescale Semiconductor, MC68HC912B32VFU8 Datasheet - Page 237

• Manufacturer Part Number: MC68HC912B32VFU8
• Manufacturer: Freescale Semiconductor

Specifications of MC68HC912B32VFU8

• Cpu Family: HC12
• Device Core Size: 16b
• Frequency (max): 8MHz
• Interface Type: SCI/SPI
• Program Memory Type: EPROM
• Program Memory Size: 32KB
• Total Internal Ram Size: 1KB
• # I/os (max): 63
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• On-chip Adc: 8-chx10-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 105C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 80
• Package Type: PQFP
• Lead Free Status / Rohs Status: Not Compliant

15.9.3 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, I3 — Interrupt Source Bits
Freescale Semiconductor
If the TMIFR1 bit is set, the BDLC attempts to transmit the normalization symbol followed by the byte
in the BDR. After the byte in the BDR has been loaded into the transmit shift register, a TDRE interrupt
(see
programmer should then load the next byte of the IFR into the BDR for transmission. When the last
byte of the IFR has been loaded into the BDR, the programmer should set the TEOD bit in the BDLC
control register 2 (BCR2). This instructs the BDLC to transmit a CRC byte once the byte in the BDR is
transmitted, and then transmit an EOD symbol, indicating the end of the IFR portion of the message
frame.
However, to transmit a single byte followed by a CRC byte, the programmer should load the byte into
the BDR before the EOD symbol has been received, and then set the TMIFR1 bit. Once the TDRE
interrupt occurs, the programmer sets the TEOD bit in the BCR2. This results in the byte in the BDR
being the only byte transmitted before the IFR CRC byte, and no TDRE interrupt is generated.
If the programmer attempts to set the TMIFR1 bit immediately after the EOD symbol has been received
from the bus, the TMIFR1 bit remains in the reset state, and no attempt is made to transmit an IFR byte.
If a loss of arbitration occurs when the BDLC is transmitting any byte of a multiple byte IFR, the BDLC
goes to the loss of arbitration state, sets the appropriate flag, and ceases transmission.
If the BDLC loses arbitration during the IFR, the TMIFR1 bit is cleared and no attempt is made to
retransmit the byte in the BDR. If loss of arbitration occurs in the last bit of the IFR byte, two additional
1 bits are sent out.
These bits indicate the source of the pending interrupt request. Bits are encoded according to
15-4.
15.9.3 BDLC State Vector
Address: $00F9
The extra logic 1 bits are an enhancement to the J1850 protocol which
forces a byte boundary condition fault. This is helpful in preventing noise on
the J1850 bus from corrupting a message.
Reset:
Read:
Write:
Bit 7
Figure 15-15. BDLC State Vector Register (BSVR)
0
0
= Unimplemented
Register) occurs similar to the main message transmit sequence. The
M68HC12B Family Data Sheet, Rev. 9.1
6
0
0
I3
5
0
NOTE
I2
4
0
I1
3
0
I0
2
0
1
0
0
Bit 0
0
0
BDLC Registers
Table
237