Dedicated Baud Rate Generator - NEC mPD78F0730 Preliminary User's Manual

10.4.3 Dedicated baud rate generator

The dedicated baud rate generator consists of a source clock selector and an 8-bit programmable counter, and
generates a serial clock for transmission/reception of UART6.
Separate 8-bit counters are provided for transmission and reception.
(1) Configuration of baud rate generator
• Base clock
The clock selected by bits 3 to 0 (TPS63 to TPS60) of clock selection register 6 (CKSR6) is supplied to
each module when bit 7 (POWER6) of asynchronous serial interface operation mode register 6 (ASIM6) is
1. This clock is called the base clock and its frequency is called f
when POWER6 = 0.
• Transmission counter
This counter stops operation, cleared to 0, when bit 7 (POWER6) or bit 6 (TXE6) of asynchronous serial
interface operation mode register 6 (ASIM6) is 0.
It starts counting when POWER6 = 1 and TXE6 = 1.
The counter is cleared to 0 when the first data transmitted is written to transmit buffer register 6 (TXB6).
If data are continuously transmitted, the counter is cleared to 0 again when one frame of data has been
completely transmitted. If there is no data to be transmitted next, the counter is not cleared to 0 and continues
counting until POWER6 or TXE6 is cleared to 0.
• Reception counter
This counter stops operation, cleared to 0, when bit 7 (POWER6) or bit 5 (RXE6) of asynchronous serial
interface operation mode register 6 (ASIM6) 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.
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CHAPTER 10 SERIAL INTERFACE UART6
Preliminary User's Manual U19014EJ1V0UD
. The base clock is fixed to low level
XCLK6
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