upd78f0124hgba1-8et-a Renesas Electronics Corporation., upd78f0124hgba1-8et-a Datasheet - Page 264

• Manufacturer Part Number: upd78f0124hgba1-8et-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(2) Generation of serial clock
264
A serial clock can be generated by using baud rate generator control register 0 (BRGC0).
Select the clock to be input to the 5-bit counter by using bits 7 and 6 (TPS01 and TPS00) of BRGC0.
Bits 4 to 0 (MDL04 to MDL00) of BRGC0 can be used to select the division value of the 5-bit counter.
(a) Baud rate
(b) Error of baud rate
The baud rate can be calculated by the following expression.
• Baud rate =
f
k:
The baud rate error can be calculated by the following expression.
• Error (%) =
Cautions 1. Keep the baud rate error during transmission to within the permissible error range at
XCLK0
Example: Frequency of base clock = 2.5 MHz = 2,500,000 Hz
: Frequency of base clock selected by the TPS01 and TPS00 bits of the BRGC0 register
Value set by the MDL04 to MDL00 bits of the BRGC0 register (k = 8, 9, 10, ..., 31)
2. Make sure that the baud rate error during reception satisfies the range shown in (4)
f
the reception destination.
Permissible baud rate range during reception.
2 × k
XCLK0
Set value of MDL04 to MDL00 bits of BRGC0 register = 10000B (k = 16)
Target baud rate = 76,800 bps
Baud rate = 2.5 M/(2 × 16)
Error = (78,125/76,800 − 1) × 100
Actual baud rate (baud rate with error)
Desired baud rate (correct baud rate)
= 1.725 [%]
[bps]
= 2,500,000/(2 × 16) = 78,125 [bps]
CHAPTER 13 SERIAL INTERFACE UART0
User’s Manual U16962EJ3V0UD
− 1 × 100 [%]