HT45F75 datasheet(136/190 Pages) HOLTEK

136 / 190 page

Rev. 1.10

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Rev. 1.10

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HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale Flash MCU

Calculating the Register and Error Values

Foraclockfrequencyof4MHz,andwithBRGHclearedtozerodeterminetheBRGregistervalueN,

theactualbaudrateandtheerrorvalueforadesiredbaudrateof4800.

FromtheabovetablethedesiredbaudrateBR=fSYS/[64(N+1)]

Re-arrangingthisequationgivesN=[fSYS/(BR×64)]-1

GivingavalueforN=[4000000/(4800×64)]-1=12.0208

Toobtaintheclosestvalue,adecimalvalueof12shouldbeplacedintotheBRGregister.Thisgives

anactualorcalculatedbaudratevalueofBR=4000000/[64×(12+1)]=4808

Thereforetheerrorisequalto(4808-4800)/4800=0.16%

ThefollowingtablesshowactualvaluesofbaudrateanderrorvaluesforthetwovaluesofBRGH.

Baud Rate

K/BPS

Baud Rates for BRGH=0

fSYS=4MHz

fSYS=3.579545MHz

fSYS=7.159MHz

BRG

Kbaud Error (%)

BRG

Kbaud Error (%)

BRG

Kbaud Error (%)

0.3

�07

0.300

0.1�

185

0.300

0.00

—

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1.�0�

0.1�

��

1.190

-0.83

9�

1.�03

0.�3

�.�

�5

�.�0�

0.1�

��

�.�3�

1.3�

��

�.380

-0.83

�.8

1�

�.808

0.1�

�.��1

-�.90

��

�.8�3

1.3�

9.�

�

8.9�9

-�.99

9.3�1

-�.90

9.33�

-�.90

19.�

�

�0.833

8.51

�

18.��3

-�.90

18.��3

-�.90

38.�

—

�

3�.�8�

-�.90

57.�

��.500

8.51

55.930

-�.90

55.930

-�.90

115.�

—

111.859

-�.90

Baud Rates and Error Values for BRGH=0

Baud Rate

K/BPS

Baud Rates for BRGH=1

fSYS=4MHz

fSYS=3.579545MHz

fSYS=7.159MHz

BRG

Kbaud

Error (%)

BRG

Kbaud

Error (%)

BRG

Kbaud Error (%)

0.3

—

1.�

�07

1.�0�

0.1�

185

1.�03

0.�3

—

�.�

103

�.�0�

0.1�

9�

�.�0�

0.�3

185

�.�0�

0.�3

�.8

�.808

0.1�

��

�.7�

-0.83

9�

�.811

0.�3

9.�

�5

9.�15

0.1�

��

9.7�7

1.3�

��

9.5�0

-0.83

19.�

1�

19.�31

0.1�

18.��3

-�.90

��

19.�5�

1.3�

38.�

�

35.71�

-�.99

37.�8�

-�.90

37.�8�

-�.90

57.�

��.5

8.51

55.930

-�.90

55.930

-�.90

115.�

1�5

8.51

111.8�

-�.90

111.8�

-�.90

�50

—

Baud Rates and Error Values for BRGH=1

HT45F75 Datasheet(PDF) 136 Page - Holtek Semiconductor Inc

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