SERIAL COMMUNICATION INTERFACE (SCI)
MOTOROLA
PORT C
6 - 19
RWU can be used by the programmer to ignore messages that are for other devices on a
multidrop serial network. Wakeup on idle line (WAKE=0) or wakeup on address bit
(WAKE=1) must be chosen.
1. When WAKE equals zero and RWU equals one, the receiver will not respond
to data on the data line until an idle line is detected.
2. When WAKE equals one and RWU equals one, the receiver will not respond
to data on the data line until a data byte with bit 9 equal to one is detected.
When the receiver wakes up, the RWU bit is cleared, and the first byte of data is received.
If interrupts are enabled, the CPU will be interrupted, and the interrupt routine will read the
message header to determine if the message is intended for this DSP.
1. If the message is for this DSP, the message will be received, and RWU will
again be set to one to wait for the next message.
2. If the message is not for this DSP, the DSP will immediately set RWU to one.
Setting RWU to one causes the DSP to ignore the remainder of the message
and wait for the next message.
RWU is cleared by hardware and software reset. RWU is a don’t care in the synchronous mode.
6.3.2.1.6
SCR Wired-OR Mode Select (WOMS) Bit 7
When the WOMS bit is set, the SCI TXD driver is programmed to function as an open-
drain output and may be wired together with other TXD pins in an appropriate bus config-
uration such as a master-slave multidrop configuration. An external pullup resistor is re-
quired on the bus. When the WOMS is cleared, the TXD pin uses an active internal pullup.
This bit is cleared by hardware and software reset.
6.3.2.1.7
SCR Receiver Enable (RE) Bit 8
When RE is set, the receiver is enabled. When RE is cleared, the receiver is disabled, and
data transfer is inhibited to the receive data register (SRX) from the receive shift register.
If RE is cleared while a character is being received, the reception of the character will be
completed before the receiver is disabled. RE does not inhibit RDRF or receive interrupts.
RE is cleared by a hardware and software reset.
6.3.2.1.8
SCR Transmitter Enable (TE) Bit 9
When TE is set, the transmitter is enabled. When TE is cleared, the transmitter will com-
plete transmission of data in the SCI transmit data shift register; then the serial output is
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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