Operating Description Of Uart/Sio Dedicated Baud Rate Generator - Fujitsu F2MC-8FX Hardware Manual

21.4 Operating Description of UART/SIO Dedicated Baud Rate
Generator
The UART/SIO dedicated baud rate generator serves as the baud rate generator for
asynchronous clock mode.
Baud Rate Setting
The SMC10 register (CKS bit) of the UART/SIO is used to select the serial clock. This selects the UART/
SIO dedicated baud rate generator.
In asynchronous CLK mode, the shift clock that is selected by the CKS bit and divided by four is used and
transfers can be performed within the range from -2% to +2%. The baud rate calculation formula for the
UART/SIO dedicated baud rate generator is shown below.
Figure 21.4-1 Baud Rate Calculation Formula when UART/SIO Dedicated Baud Rate Generator Is Used
Baud rate =
UART dedicated baud rate generator
prescaler selection register (PSSR)
Prescaler selection (PSS1, PSS2)
Table 21.4-1Sample Asynchronous Transfer Rates by Baud Rate Generator (Machine Clock = 10MHz)
UART/SIO Dedicated baud rate generator setting
Prescaler selection
PSS[1:0]
1 (Setting value: 0, 0)
1 (Setting value: 0, 0)
1 (Setting value: 0, 0)
1 (Setting value: 0, 0)
1 (Setting value: 0, 0)
2 (Setting value: 0, 1)
4 (Setting value: 1, 0)
8 (Setting value: 1, 1)
The baud rate can be set in UART mode within the following range.
Table 21.4-2 Permissible Baud Rate Range in UART Mode
CHAPTER 21 UART/SIO DEDICATED BAUD RATE GENERATOR
Machine clock (MCLK)
4
×
Baud rate counter setting
BRS[7:0]
20
22
44
87
130
130
130
130
PSS[1:0]
"0, 0" to "1, 1"
1
2
×
4
8
UART dedicated baud rate generator
baud rate setting register (BRSR)
Baud rate setting (BRS7 to BRS0)
UART internal Total division ratio
division (PSS x BRS x4)
4
4
4
4
4
4
4
4
BRS[7:0]
02 (2) to FF (255)
H H
[bps]
2
:
255
(10MHz/Total division ratio)
80
88
176
348
520
1040
2080
4160
Baud rate
125000
113636
56818
28736
19231
9615
4808
2404
367