Datasheet

PIC18F47J13 FAMILY
DS39974A-page 350 Preliminary  2010 Microchip Technology Inc.
EXAMPLE 21-1: CALCULATING BAUD RATE ERROR
TABLE 21-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
TXSTAx
CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D
RCSTAx SPEN RX9 SREN CREN ADDEN FERR OERR RX9D
BAUDCONx
ABDOVF RCIDL RXDTP TXCKP BRG16 — WUE ABDEN
SPBRGHx EUSARTx Baud Rate Generator High Byte
SPBRGx EUSARTx Baud Rate Generator Low Byte
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, and
8-bit BRG:
Desired Baud Rate = Fosc/(64 ([SPBRGHx:SPBRGx] + 1))
Solving for SPBRGHx:SPBRGx:
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%