MC68F375BGMZP33 Freescale Semiconductor, MC68F375BGMZP33 Datasheet - Page 290

• Manufacturer Part Number: MC68F375BGMZP33
• Description: IC MPU 32BIT 33MHZ 217-PBGA
• Manufacturer: Freescale Semiconductor

Specifications of MC68F375BGMZP33

• Processor Type: M683xx 32-Bit
• Speed: 33MHz
• Voltage: 5V
• Mounting Type: Surface Mount
• Package / Case: 217-PBGA
• Processor Series: M683xx
• Core: CPU32
• Data Bus Width: 32 bit
• Program Memory Type: Flash
• Program Memory Size: 256 KB
• Data Ram Size: 10 KB
• Interface Type: SPI, SCI, CAN
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 48
• Number Of Timers: 16
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 16 Channel
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Lead Free Status / Rohs Status: No

6.8.7.8 Receiver Wake-Up
MC68F375
REFERENCE MANUAL
For short idle-line detection, the receiver bit processor counts contiguous logic one bit-
times whenever they occur. Short detection provides the earliest possible recognition
of an idle-line condition, because the stop bit and contiguous logic ones before and
after it are counted. For long idle-line detection, the receiver counts logic ones after the
stop bit is received. Only a complete idle frame causes the IDLE flag to be set.
In some applications, software overhead can cause a bit-time of logic level one to
occur between frames. This bit-time does not affect content, but if it occurs after a
frame of ones when short detection is enabled, the receiver flags an idle line.
When the ILIE bit in SCCxR1 is set, an interrupt request is generated when the IDLE
flag is set. The flag is cleared by reading SCxSR and SCxDR in sequence. For
receiver queue operation, IDLE is cleared when SCxSR is read with IDLE set, followed
by a read of SCRQ[0:15]. IDLE is not set again until after at least one frame has been
received (RDRF = 1). This prevents an extended idle interval from causing more than
one interrupt.
The receiver wake-up function allows a transmitting device to direct a transmission to
a single receiver or to a group of receivers by sending an address frame at the start of
a message. Hardware activates each receiver in a system under certain conditions.
Resident software must process address information and enable or disable receiver
operation.
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. How-
ever, there is a loss of efficiency because of an additional bit-time per frame.
Freescale Semiconductor, Inc.
QUEUED SERIAL MULTI-CHANNEL MODULE
For More Information On This Product,
Go to: www.freescale.com
Rev. 25 June 03
MOTOROLA
6-56