UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 468

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

16.4.3 Baud Rate Generator Operation
rate clock is a signal scaled from the internal clock (f
rate input (ASCK) pin.
(1) Baud rate clock generation in UART mode
428
The baud rate generator only operates when UART/IOE transmit/receive operations are enabled. The generated baud
Caution If a write to the baud rate generator control register (BRGC) is performed during communication, the
(a) Using internal clock (f
(b) Using external baud rate input
This function is selected by setting (1) bit 0 (SCK) of the asynchronous serial interface mode register (ASIM).
The internal clock (f
the signal further divided by 2 is used as the baud rate. The baud rate is given by the following expression:
f
k : Value set in bits MDL3 to MDL0 of BRGC (k = 0 to 14)
n : Value set in bits TPS3 to TPS0 of BRGC (n = 0 to 11)
This function is selected by clearing (0) bit 0 (SCK) of the asynchronous serial interface mode register (ASIM).
When this function is used, bits MDL3 to MDL0 of the baud rate generator control register (BRGC) must all be
cleared (0) (k= 0).
When this function is used with UART2, it is necessary to set (1) bit 2 of the port 3 mode control register (PMC3)
and set the P12 pin to control mode.
The ASCK pin input clock is scaled by the frequency divider, and the signal obtained by dividing this signal by 32
(f
XX
PRS
: Oscillator frequency or external clock input
generated baud rate clock may be disrupted, preventing normal communication from continuing. The
BRGC should therefore not be written to during communication.
) (division by 16 and division by 2) is used as the baud rate. The baud rate is given by the following expression:
CHAPTER 16 ASYNCHRONOUS SERIAL INTERFACE/3-WIRE SERIAL I/O
XX
/2) is scaled by the frequency divider, this signal (f
XX
/2)
(Baud rate) =
XX
/2) or a signal scaled from the clock input from the external baud
(
k
16 2
f
XX
)
n
3
PRS
) is scaled by the 5-bit counter, and