Queued Serial Multi-Channel Module
MPC561/MPC563 Reference Manual, Rev. 1.2
Freescale Semiconductor
15-59
A receiver is placed in wake-up mode by setting the RWU bit in SCCxR1. While RWU is set, receiver
status flags and interrupts are disabled. Although the software can clear RWU, it is normally cleared by
hardware during wake-up.
The WAKE bit in SCCxR1 determines which type of wake-up is used. When WAKE = 0, idle-line wake-up
is selected. When WAKE = 1, address-mark wake-up is selected. Both types require a software-based
device addressing and recognition scheme.
Idle-line wake-up allows a receiver to sleep until an idle line is detected. When an idle line is detected, the
receiver clears RWU and wakes up. The receiver waits for the first frame of the next transmission. The
data frame is received normally, transferred to the RDRx, and the RDRF flag is set. If software does not
recognize the address, it can set RWU and put the receiver back to sleep. For idle-line wake-up to work,
there must be a minimum of one frame of idle line between transmissions. There must be no idle time
between frames within a transmission.
Address mark wake-up uses a special frame format to wake up the receiver. When the MSB of an
address-mark frame is set, that frame contains address information. The first frame of each transmission
must be an address frame. When the MSB of a frame is set, the receiver clears RWU and wakes up. The
data frame is received normally, transferred to the RDRx, and the RDRF flag is set. If software does not
recognize the address, it can set RWU and put the receiver back to sleep. Address mark wake-up allows
idle time between frames and eliminates idle time between transmissions. However, there is a loss of
efficiency because of an additional bit-time per frame.
15.7.7.11 Internal Loop Mode
The LOOPS bit in SCCxR1 controls a feedback path in the data serial shifter. When LOOPS is set, the SCI
transmitter output is fed back into the receive serial shifter. TXD is asserted (idle line). Both transmitter
and receiver must be enabled before entering loop mode.
15.8
SCI Queue Operation
15.8.1
Queue Operation of SCI1 for Transmit and Receive
The SCI1 serial module allows for queueing on transmit and receive data frames. In the standard mode, in
which the queue is disabled, the SCI1 operates as previously defined (i.e., transmit and receive operations
done via SC1DR). However, if the SCI1 queue feature is enabled (by setting the QTE and/or QRE bits
within QSCI1CR) a set of 16 entry queues is allocated for the receive and/or transmit operation. Through
software control the queue is capable of continuous receive and transfer operations within the SCI1 serial
unit.
15.8.2
Queued SCI1 Status and Control Registers
The SCI1 queue uses the following registers:
•
QSCI1 control register (QSCI1CR, address offset 0x28)
•
QSCI1 status register (QSCI1SR, address offset 0x2A)
Summary of Contents for MPC561
Page 84: ...MPC561 MPC563 Reference Manual Rev 1 2 lxxxiv Freescale Semiconductor...
Page 144: ...Signal Descriptions MPC561 MPC563 Reference Manual Rev 1 2 2 46 Freescale Semiconductor...
Page 206: ...Central Processing Unit MPC561 MPC563 Reference Manual Rev 1 2 3 62 Freescale Semiconductor...
Page 302: ...Reset MPC561 MPC563 Reference Manual Rev 1 2 7 14 Freescale Semiconductor...
Page 854: ...Time Processor Unit 3 MPC561 MPC563 Reference Manual Rev 1 2 19 24 Freescale Semiconductor...
Page 968: ...Development Support MPC561 MPC563 Reference Manual Rev 1 2 23 54 Freescale Semiconductor...
Page 1144: ...Internal Memory Map MPC561 MPC563 Reference Manual Rev 1 2 B 34 Freescale Semiconductor...
Page 1212: ...TPU3 ROM Functions MPC561 MPC563 Reference Manual Rev 1 2 D 60 Freescale Semiconductor...
Page 1216: ...Memory Access Timing MPC561 MPC563 Reference Manual Rev 1 2 E 4 Freescale Semiconductor...