HD64570 HITACHI [Hitachi Semiconductor], HD64570 Datasheet - Page 135

• Manufacturer Part Number: HD64570
• Description: Serial Communications Adaptor
• Manufacturer: HITACHI [Hitachi Semiconductor]

Bits 7 6: Reserved. These bits always read 0 and must be set to 0.
Bit 5 (UDRNC: Underrun State Control): Specifies the transmit operation in underrun state in
byte or bit synchronous mode.
If the UDRNC bit is set to 0 so as to set the transmitter to the idle state after transmitting an abort
frame, a zero may not be inserted immediately before the abort frame. The receiver should thus
discard the data immediately preceding the abort frame.
Bit 4 (IDLC: Idle State Control): Specifies the TXD line output in idle state in byte or bit
synchronous mode.
Bit 3 (BRK: Send Break): Specifies whether or not to transmit a break in asynchronous mode.
Asynchronous mode
Reserved. This bit always reads 0 and must be set to 0.
Byte synchronous mode
UDRNC = 0: Sets the transmitter to idle state in underrun state
UDRNC = 1: Sets the transmitter to idle state after CRC code transmission in underrun state
Bit synchronous mode
UDRNC = 0: Sets the transmitter to idle state after aborting transmission in underrun state
UDRNC = 1: Sets the transmitter to idle state after FCS (CRC code) and flag transmission in
underrun state
Asynchronous mode
Reserved. This bit always reads 0 and must be set to 0.
Byte synchronous/Bit synchronous mode
IDLC = 0:
IDLC = 1:
state
Asynchronous mode
BRK = 0:
BRK = 1:
the transmit clock. The TXD line must be low for two or more character cycles to transmit a
break.
The BRK bit is cleared by a TX reset command.
For details on breaks, see Break Transmission and Detection, in section 5.3.1, Asynchronous
Mode.
Byte synchronous/Bit synchronous mode
Reserved. This bit always reads 0 and must be set to 0.
Sets the TXD line high (mark) in idle state
Repeatedly transmits 8-bit idle patterns in the idle pattern register (IDL) in idle
Transmits no break (normal operation).
Transmits a break by setting the TXD line low (space) at the next falling edge of
Rev. 0, 07/98, page 119 of 453