PIC18LF4331T-I/SO View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18LF4331T-I/SO

28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High-Performance PWM and A/D

Microchip Technology 

PIC18F2331/2431/4331/4431

EXAMPLE 20-1: CALCULATING BAUD RATE ERROR

For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG:

Desired Baud Rate = FOSC/(64 ([SPBRGH:SPBRG] + 1))

Solving for SPBRGH:SPBRG:

X = ((FOSC/Desired Baud Rate)/64) – 1

= ((16000000/9600)/64) – 1

= [25.042] = 25

Calculated Baud Rate = 16000000/(64 (25 + 1))

= 9615

Error = (Calculated Baud Rate – Desired Baud Rate)/Desired Baud Rate

= (9615 – 9600)/9600 = 0.16%

TABLE 20-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR

Name

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

TXSTA

CSRC

TX9

TXEN SYNC SENDB BRGH TRMT

RCSTA

SPEN

RX9

SREN CREN ADDEN FERR OERR

BAUDCON

—

RCIDL

—

SCKP BRG16

—

WUE

SPBRGH EUSART Baud Rate Generator Register High Byte

SPBRG

EUSART Baud Rate Generator Register Low Byte

Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.

Bit 0

Reset Values

on Page:

TX9D

56

RX9D

56

ABDEN

56

56

56

TABLE 20-3: BAUD RATES FOR ASYNCHRONOUS MODES

BAUD

RATE

(K)

SYNC = 0, BRGH = 0, BRG16 = 0

FOSC = 40.000 MHz

FOSC = 20.000 MHz

FOSC = 10.000 MHz

FOSC = 8.000 MHz

Actual

Rate

(K)

%

Error

SPBRG Actual

value Rate

(decimal) (K)

%

Error

SPBRG Actual

value Rate

(decimal) (K)

%

Error

SPBRG Actual

value Rate

(decimal) (K)

%

Error

SPBRG

value

(decimal)

0.3

—

—

—

—

—

—

—

—

—

—

—

—

1.2

—

—

—

1.221 1.73

255

1.202 0.16

129

1.201 -0.16

103

2.4

2.441 1.73

255

2.404 0.16

129

2.404 0.16

64

2.403 -0.16

51

9.6

9.615 0.16

64

9.766 1.73

31

9.766 1.73

15

9.615 -0.16

12

19.2 19.531 1.73

31

19.531 1.73

15

19.531 1.73

7

—

—

—

57.6 56.818 -1.36

10

62.500 8.51

4

52.083 -9.58

2

—

—

—

115.2 125.000 8.51

4

104.167 -9.58

2

78.125 -32.18

1

—

—

—

BAUD

RATE

(K)

0.3

1.2

2.4

9.6

19.2

57.6

115.2

SYNC = 0, BRGH = 0, BRG16 = 0

FOSC = 4.000 MHz

FOSC = 2.000 MHz

FOSC = 1.000 MHz

Actual

Rate

(K)

%

Error

SPBRG Actual

value Rate

(decimal) (K)

%

Error

SPBRG Actual

value Rate

(decimal) (K)

%

Error

SPBRG

value

(decimal)

0.300 0.16

207

0.300 -0.16

103

0.300 -0.16

51

1.202 0.16

51

1.201 -0.16

25

1.201 -0.16

12

2.404 0.16

25

2.403 -0.16

12

—

—

—

8.929 -6.99

6

—

—

—

—

—

—

20.833 8.51

2

—

—

—

—

—

—

62.500 8.51

0

—

—

—

—

—

—

62.500 -45.75

0

—

—

—

—

—

—

DS39616D-page 222

 2010 Microchip Technology Inc.

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