Z8F6421PM020SC Datasheet, PDF (136/299 Pages) Zilog, Inc. – High Performance 8-Bit Microcontrollers Z8 Encore-R 64K Series

Z8 Encore!^® 64K Series
Product Specification
116
Table 58. UART Baud Rate High Byte Register (UxBRH)
BITS
7
6
5
4
3
2
1
0
FIELD
BRH
RESET
R/W
ADDR
1
R/W
F46H and F4EH
Table 59. UART Baud Rate Low Byte Register (UxBRL)
BITS
7
6
5
4
3
2
1
0
FIELD
BRL
RESET
1
R/W
R/W
ADDR
F47H and F4FH
For a given UART data rate, the integer baud rate divisor value is calculated using the fol-
lowing equation:
UART Baud Rate Divisor Value (BRG) = Round_⎝⎛^{S-1---y6---s--}_×^{t--e--U-m----A--C--R---l-oT---c---Dk----a-F--t--ra--e---Rq---u-a---et--en----c(--by----i-(t--Hs---/-sz---))}_⎠⎞
The baud rate error relative to the desired baud rate is calculated using the following equa-
tion:
UART Baud Rate Error (%)
=
100
×
⎛
⎝
A-----c---t--u---a---l---D----a---t-D-a---e--R-s--i-a-r--te--e-d---∠_{--D----aD---t--ea--s---Ri-r---ae---dt--e---D----a---t--a----R-----a---t--e-⎠⎞}
For reliable communication, the UART baud rate error must never exceed 5 percent.
Table 60 provides information on data rate errors for popular baud rates and commonly
used crystal oscillator frequencies.
PS019915-1005
UART