Datasheet

Table Of Contents
PIC18F85J90 FAMILY
DS39770C-page 240 2010 Microchip Technology Inc.
EXAMPLE 18-1: CALCULATING BAUD RATE ERROR
TABLE 18-2: REGISTERS ASSOCIATED WITH THE BAUD RATE GENERATOR
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset Values
on Page
TXSTA1
CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 59
RCSTA1 SPEN
RX9 SREN CREN ADDEN FERR OERR RX9D 59
BAUDCON1 ABDOVF RCIDL RXDTP TXCKP BRG16 WUE ABDEN 61
SPBRGH1 EUSART Baud Rate Generator Register High Byte 61
SPBRG1 EUSART Baud Rate Generator Register Low Byte 59
Legend: — = unimplemented, read as ‘0. Shaded cells are not used by the BRG.
For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG:
Desired Baud Rate = F
OSC/(64 ([SPBRGH1:SPBRG1] + 1))
Solving for SPBRGH1:SPBRG1:
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%