MC68HC711PH8 Motorola, MC68HC711PH8 Datasheet - Page 93

• Manufacturer Part Number: MC68HC711PH8
• Description: High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit
• Manufacturer: Motorola

The serial communications interface (SCI) is a universal asynchronous receiver transmitter
(UART). It has a non-return to zero (NRZ) format (one start, eight or nine data, and one stop bit)
that is compatible with standard RS-232 systems.
The SCI shares I/O with two of port D’s pins:
The SCI transmit and receive functions are enabled by TE and RE respectively, in SCCR2.
The SCI features enabled on this MCU include: 13-bit modulus prescaler, idle line detect,
receiver-active flag, transmitter and receiver hardware parity. A block diagram of the enhanced
baud rate generator is shown in Figure 5-1. See Table 5-1 for example baud rate control values.
MC68HC11PH8
ST4XCK
†
SERIAL COMMUNICATIONS INTERFACE
The MC68HC11PH8 contains two serial communications interfaces, both having similar
operation. For ease of reference, a full description of SCI1 (PD0/RXD1, PD1/TXD1) is given
first, followed by a summary of SCI2 (Section 5.8), detailing its differences.
SCBDH/L: SCI baud control
13-bit compare
13-bit counter
Figure 5-1 SCI baud rate generator circuit diagram
SERIAL COMMUNICATIONS INTERFACE
Reset
EQ
PD0
PD1
Pin
5
Alternate
function
2
RXD1
TXD1
phase 2 clock
Internal
Sync
16
Transmitter
MOTOROLA
baud rate
baud rate
Receiver
clock
clock
†
TPG
5-1
5