Operating Description Of Operation Mode 0 - Fujitsu F2MC-8FX Hardware Manual

CHAPTER 20 UART/SIO
20.7.1

Operating Description of Operation Mode 0

Operation mode 0 operates as clock asynchronous mode (UART).
Operating Description of UART/SIO Operation Mode 0
Clock asynchronous mode (UART) is selected when the MD bit in the UART/SIO serial mode control
register 1 (SCM10) is set to 0.
Baud rate
The serial clock is selected by the CKS bit in the SMC10 register. Be sure to select the dedicated baud rate
generator at this time.
The baud rate is equivalent to the output clock frequency of the dedicated baud rate generator, divided by
four. The UART can perform communication within the range from -2% to +2% of the selected baud rate.
The baud rate generated by the dedicated baud rate generator is obtained from the equation illustrated
below. (For information about the dedicated baud rate generator, refer to "CHAPTER 21 UART/SIO
DEDICATED BAUD RATE GENERATOR")
Figure 20.7-1 Baud Rate Calculation when Using Dedicated Baud Rate Generator
Baud rate value =
UART prescaler selection register (PSSR)
Prescaler selection (PSS1, PSS2)
Table 20.7-2 Sample Asynchronous Transfer Rates Based on Dedicated Baud Rate Generator
(Clock Gear = 4/F
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)
344
4
×
, Machine Clock = 10MHz)
CH
Baud rate counter setting
BRS[7:0]
20
22
44
87
130
130
130
130
Machine clock (MCLK)
1
2
×
4
8
UART baud rate setting register
(BRSR)
Baud rate setting (BRS7 to BRS0)
Internal
Total division ratio
UART
(PSS x BRS x 4)
division
4
4
4
4
4
4
4
4
[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