XC68HC705F32 Motorola, XC68HC705F32 Datasheet - Page 113

• Manufacturer Part Number: XC68HC705F32
• Description: MICROCONTROLLER
• Manufacturer: Motorola

11.6
Receive data or transmit data is the serial data that is transferred to the internal data bus from the
receive data input pin (RDI) or from the internal bus to the transmit data output pin (TDO). The
non-return-to-zero (NRZ) data format shown in
criteria:
11.7
The receiver logic hardware also supports a receiver wake-up function which is intended for
systems having more than one receiver. With this function a transmitting device directs messages
to an individual receiver or group of receivers by passing addressing information as the initial
byte(s) of each message. The wake-up function allows receivers not addressed to remain in a
dormant state for the remainder of the unwanted message. This eliminates any further software
overhead to service the remaining characters of the unwanted message and thus improves system
performance.
The receiver is placed in wake-up mode by setting the receiver wake-up bit (RWU) in the SCCR2
register. While RWU is set, all of the receiver related status flags (RDRF, IDLE, OR, NF, and FE)
are inhibited (cannot become set). Note that the idle line detect function is inhibited while the RWU
bit is set. Although RWU may be cleared by a software write to SCCR2, it would be unusual to do
so. Normally RWU is set by software and is cleared automatically in hardware by one of the two
methods described below.
MC68HC05F32
– The idle line is brought to a logic one state prior to transmission/reception of
– A start bit (logic zero) is used to indicate the start of a frame.
– The data is transmitted and received least significant bit first.
– A stop bit (logic one) is used to indicate the end of a frame. A frame consists
– A break is defined as the transmission or reception of a low (logic zero) for at
a character.
of a start bit, a character of eight or nine data bits, and a stop bit.
least one complete frame time (10 zeros for 8-bit format, 11 zeros for 9-bit).
Data format
Receiver wake-up operation
Idle line
SERIAL COMMUNICATIONS INTERFACE
Start
Figure 11-3 Data format
0
1
2
Figure 11-3
3
4
5
Control bit M selects
is used and must meet the following
8 or 9 bit data
6
7
8
Stop
Start
0
MOTOROLA
TPG
11-5
11