CHAPTER 11 SERIAL INTERFACE FUNCTION
User’s Manual U14359EJ4V0UM
385
(c) Baud rate
The baud rate is the value obtained according to the following formula.
[bps]
k
2
f
rate
Baud
XCLK
×
=
f
XCLK
= Frequency of basic clock selected according to TPSn3 to TPSn0 bits of CKSRn register.
k = Value set according to BRGn7 to BRGn0 bits of BRGCn register (k = 8, 9, 10, ..., 255)
(d) Baud rate error
The baud rate error is obtained according to the following formula.
[%]
100
1
rate)
baud
(normal
rate
baud
Desired
error)
with
rate
(baud
rate
baud
Actual
(%)
Error
×
−
=
Cautions 1. Make sure that the baud rate error during transmission does not exceed the allowable
error of the reception destination.
2. Make sure that the baud rate error during reception is within the allowable baud rate
range during reception, which is described in paragraph (4).
Example:
Basic clock frequency = 20 MHz = 20,000,000 Hz
Settings of BRGn7 to BRGn0 bits in BRGCn register = 01000001B (k = 65)
Target baud rate = 153,600 bps
Baud rate = 20 M/(2
×
65)
= 20,000,000/(2
×
65) = 153,846 [bps]
Error = (153,846/153,600
−
1)
×
100
= 0.160 [%]
