Z8F4822AR020SG Datasheet, PDF (118/323 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers

Z8 Encore! XP^® F64xx Series
Product Specification
98
UART Baud Rate Generator
The UART Baud Rate Generator creates a lower frequency baud rate clock for data trans-
mission. The input to the Baud Rate Generator is the system clock. The UART Baud Rate
High and Low Byte registers combine to create a 16-bit baud rate divisor value
(BRG[15:0]) that sets the data transmission rate (baud rate) of the UART. The UART data
rate is calculated using the following equation:
UART Data Rate (bits/s)
=
---------S----y---s--t--e--m-------C----l-o---c---k-----F---r--e---q---u---e--n---c---y----(--H-----z--)----------
16  UART Baud Rate Divisor Value
When the UART is disabled, the Baud Rate Generator can function as a basic 16-bit timer
with interrupt on time-out. To configure the Baud Rate Generator as a timer with interrupt
on time-out, complete the following procedure:
1. Disable the UART by clearing the REN and TEN bits in the UART Control 0 Register
to 0.
2. Load the appropriate 16-bit count value into the UART Baud Rate High and Low Byte
registers.
3. Enable the Baud Rate Generator timer function and associated interrupt by setting the
BRGCTL bit in the UART Control 1 Register to 1.
When configured as a general purpose timer, the interrupt interval is calculated using the
following equation:
Interrupt Intervals = System Clock Period (s)  BRG15:0
UART Control Register Definitions
The UART control registers support the UART and the associated Infrared Encoder/
Decoders. For more information about the infrared operation, see the Infrared Encoder/
Decoder chapter on page 109.
UART Transmit Data Register
Data bytes written to the UART Transmit Data Register, shown in Table 53, are shifted out
on the TXDx pin. The write-only UART Transmit Data Register shares a Register File
address with the read-only UART Receive Data Register.
PS019924-0113
PRELIMINARY
UART Control Register Definitions