CHAPTER 13 SERIAL INTERFACE UART0
Preliminary User’s Manual U16315EJ1V0UD
262
13.4.3 Dedicated baud rate generator
The dedicated baud rate generator consists of a source clock selector and a 5-bit programmable counter, and
generates a serial clock for transmission/reception of UART0.
Separate 5-bit counters are provided for transmission and reception.
(1) Configuration of baud rate generator
•
Base clock (Clock)
The clock selected by bits 7 and 6 (TPS01 and TPS00) of baud rate generator control register 0 (BRGC0) is
supplied to each module when bit 7 (POWER0) of asynchronous serial interface operation mode register 0
(ASIM0) is 1. This clock is called the base clock “Clock” and its frequency is called f
XCLK
. “Clock” is fixed to
low level when POWER0 = 0.
•
Transmission counter
This counter stops, cleared to 0, when bit 7 (POWER0) or bit 6 (TXE0) of asynchronous serial interface
operation mode register 0 (ASIM0) is 0.
It starts counting when POWER0 = 1 and TXE0 = 1.
The counter is cleared to 0 when the first data transmitted is written to transmit shift register 0 (TXS0).
•
Reception counter
This counter stops operation, cleared to 0, when bit 7 (POWER0) or bit 5 (RXE0) of asynchronous serial
interface operation mode register 0 (ASIM0) is 0.
It starts counting when the start bit has been detected.
The counter stops operation after one frame has been received, until the next start bit is detected.
Figure 13-10. Configuration of Baud Rate Generator
Clock
(f
XCLK
)
Selector
POWER0
5-bit counter
Match detector
Baud rate
BRGC0: MDL04 to MDL00
1/2
POWER0, TXE0 (or RXE0)
BRGC0: TPS01, TPS00
TO50/TI50/P17
(TM50 output)
f
X
/2
5
f
X
/2
f
X
/2
3
Remark
POWER0: Bit 7 of asynchronous serial interface operation mode register 0 (ASIM0)
TXE0:
Bit 6 of ASIM0
RXE0:
Bit 5 of ASIM0
BRGC0:
Baud rate generator control register 0
Содержание 78K0/KD1 Series
Страница 2: ...Preliminary User s Manual U16315EJ1V0UD 2 MEMO ...
Страница 444: ...Preliminary User s Manual U16315EJ1V0UD 444 MEMO ...