CHAPTER 11 SERIAL INTERFACE UART0 (
µ
PD78F0102H AND 78F0103H ONLY)
Preliminary User’s Manual U16846EJ1V0UD
222
Minimum permissible data frame length: FLmin = 11
×
FL
−
×
FL = FL
Therefore, the maximum receivable baud rate at the transmission destination is as follows.
BRmax = (FLmin/11)
−
1
= Brate
Similarly, the maximum permissible data frame length can be calculated as follows.
10
k + 2
21k
−
2
11
2
×
k
2
×
k
FLmax = FL
×
11
Therefore, the minimum receivable baud rate at the transmission destination is as follows.
BRmin = (FLmax/11)
−
1
= Brate
The permissible baud rate error between UART0 and the transmission destination can be calculated from the
above minimum and maximum baud rate expressions, as follows.
Table 11-5. Maximum/Minimum Permissible Baud Rate Error
Division Ratio (k)
Maximum Permissible Baud Rate Error
Minimum Permissible Baud Rate Error
8 +3.53%
−
3.61%
16 +4.14%
−
4.19%
24 +4.34%
−
4.38%
31 +4.44%
−
4.47%
Remarks 1. The permissible reception error depends on the number of bits in one frame, input clock
frequency, and division ratio (k). The higher the input clock frequency and the higher the division
ratio (k), the higher the permissible reception error.
2. k: Set value of BRGC0
k
−
2
2k
21k + 2
2k
22k
21k + 2
×
FLmax = 11
×
FL
−
×
FL = FL
21k
−
2
20k
20k
21k
−
2