SC28L92 Philips Semiconductors, SC28L92 Datasheet - Page 28

• Manufacturer Part Number: SC28L92
• Description: 3.3V-5.0V Dual Universal Asynchronous Receiver/Transmitter DUART
• Manufacturer: Philips Semiconductors

Access to the miscellaneous commands should be separated by 3 X1 clock edges. A disabled transmitter cannot be loaded.
Philips Semiconductors
CRA—Channel A Command Register
CRA is a register used to supply commands to Channel A. Multiple commands can be specified in a single write to CRA as long as the
commands are non-conflicting, e.g., the ‘enable transmitter’ and ‘reset transmitter’ commands cannot be specified in a single command word.
CR COMMAND REGISTER
NOTES:
CRA[7:4]—Miscellaneous Commands
Execution of the commands in the upper four bits of this register
must be separated by 3 X1 clock edges. Other reads or writes
(including writes tot he lower four bits) may be inserted to achieve
this separation.
CRA[7:4]—Commands
2000 Jan 21
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
3.3V–5.0V Dual Universal Asynchronous
Receiver/Transmitter (DUART)
CRA/B
Addr
0x0A
0x02
No command.
Reset MR pointer. Causes the Channel A MR pointer to
point to MR1.
Reset receiver. Resets the Channel A receiver as if a
hardware reset had been applied. The receiver is
disabled and the FIFO is flushed.
Reset transmitter. Resets the Channel A transmitter as
if a hardware reset had been applied.
Reset error status. Clears the Channel A Received
Break, Parity Error, and Overrun Error bits in the status
register (SRA[7:4]). Used in character mode to clear OE
status (although RB, PE and FE bits will also be
cleared) and in block mode to clear all error status after
a block of data has been received.
Reset Channel A break change interrupt. Causes the
Channel A break detect change bit in the interrupt
status register (ISR[2]) to be cleared to zero
Start break. Forces the TxDA output Low (spacing). If
the transmitter is empty the start of the break condition
will be delayed up to two bit times. If the transmitter is
active the break begins when transmission of the
character is completed. If a character is in the TxFIFO,
the start of the break will be delayed until that character,
or any other loaded subsequently are transmitted. The
transmitter must be enabled for this command to be
accepted.
Stop break. The TxDA line will go High (marking) within
two bit times. TxDA will remain High for one bit time
before the next character, if any, is transmitted.
Assert RTSN. Causes the RTSN output to be asserted
(Low).
Negate RTSN. Causes the RTSN output to be negated
(High)
Bit 7
See Text of Channel Command Register
MISCELLANEOUS COMMANDS
BIT 6
BIT 5
BIT 4
28
CRA[3]—Disable Channel A Transmitter
This command terminates transmitter operation and reset the
TxDRY and TxEMT status bits. However, if a character is being
transmitted or if a character is in the TxFIFO when the transmitter is
disabled, the transmission of the character(s) is completed before
assuming the inactive state.
CRA[2]—Enable Channel A Transmitter
Enables operation of the Channel A transmitter. The TxRDY and
TxEMT status bits will be asserted if the transmitter is idle.
1010
1011
1100
1101
1110
1111
Disable Tx
1 = Yes
0 = No
BIT 3
Set Timeout Mode On. The receiver in this channel will
restart the C/T as each receive character is transferred
from the shift register to the RxFIFO. The C/T is placed
in the counter mode, the START/STOP counter
commands are disabled, the counter is stopped, and
the Counter Ready Bit, ISR[3], is reset. (See also
Watchdog timer description in the receiver section.)
Set MR pointer to ‘0’
Disable Timeout Mode. This command returns control
of the C/T to the regular START/STOP counter
commands. It does not stop the counter, or clear any
pending interrupts. After disabling the timeout mode, a
‘Stop Counter’ command should be issued to force a
reset of the ISR(3) bit
Not used.
Power Down Mode On. In this mode, the DUART
oscillator is stopped and all functions requiring this
clock are suspended. The execution of commands
other than disable power down mode (1111) requires a
X1/CLK. While in the power down mode, do not issue
any commands to the CR except the disable power
down mode command. The contents of all registers will
be saved while in this mode. . It is recommended that
the transmitter and receiver be disabled prior to placing
the DUART into power down mode. This command is in
CRA only.
Disable Power Down Mode. This command restarts the
oscillator. After invoking this command, wait for the
oscillator to start up before writing further commands to
the CR. This command is in CRA only. For maximum
power reduction input pins should be at V
Enable Tx
1 = Yes
0 = No
BIT 2
Disable Rx
1 = Yes
0 = No
BIT 1
Product specification
SC28L92
SS
or V
Enable Rx
1 = Yes
0 = No
BIT 0
DD
.