|
MC68340FE16E Datasheet, PDF (326/441 Pages) Freescale Semiconductor, Inc – Integrated Processor with DMA User’s Manual | |||
|
◁ |
Freescale Semiconductor, Inc.
characters until the shift register is ready to accept more data. When the shift register is
empty, it checks to see if the holding register has a valid character to be sent (TxRDY bit
cleared). If there is a valid character, the shift register loads the character and reasserts
the TxRDY bit in the channel's SR. Writes to the transmitter buffer when the channel's SR
TxRDY bit is clear and when the transmitter is disabled have no effect on the transmitter
buffer. This register can only be written when the serial module is enabled (i.e., the STP
bit in the MCR is cleared).
TBA, TBB
$713, $71B
7
6
5
4
3
2
1
0
TB7
TB6
TB5
TB4
TB3
TB2
TB1
TB0
RESET:
0
0
0
0
0
0
0
0
Write Only
Supervisor/User
TB7âTB0âThese bits contain the character in the transmitter buffer.
7.4.1.10 INPUT PORT CHANGE REGISTER (IPCR). The IPCR shows the current state
and the change-of-state for the CTSA and CTSB pins. This register can only be read
when the serial module is enabled (i.e., the STP bit in the MCR is cleared).
IPCR
$714
7
6
5
4
3
2
1
0
0
0
COSB COSA
0
0
CTSB CTSA
RESET:
0
0
0
0
0
0
U
U
Read Only
Supervisor/User
Bits 7, 6, 3, 2âReserved
COSB, COSAâChange-of-State
1 = A change-of-state (high-to-low or low-to-high transition), lasting longer than 25â
50 µs when using a crystal as the sampling clock or longer than one or two
periods when using SCLK, has occurred at the corresponding CTSâ input (MCR
ICCS bit controls selection of the sampling clock for clear-to-send operation).
When these bits are set, the ACR can be programmed to generate an interrupt to
the CPU32.
0 = The CPU32 has read the IPCR. No change-of-state has occurred. A read of the
IPCR also clears the ISR COS bit.
CTSB, CTSAâCurrent State
Starting two serial clock periods after reset, the CTSâ bits reflect the state of the CTSâ
pins. If a CTSâ pin is detected as asserted at that time, the associated COSx bit will be
set, which will initiate an interrupt if the corresponding IECx bit of the ACR register is
enabled.
1 = The current state of the respective CTSâ input is negated.
0 = The current state of the respective CTSâ input is asserted.
MOTOROLA
MC68340 USERâS MANUAL
7-31
For More Information On This Product,
Go to: www.freescale.com
|
▷ |