Hardware RS232 Serial sets wrong baud rate with PIC18F25K80

[William Roth]

.
The measured TX baud rate is ~1/4 of the expected baud rate at any clock frequency or baud setting.
MCU clock speed was verified correct with output on clock out pin and testing 1 ms wait time.

Compiler: 0.94 2015-04-02

This will likely affect the following chips.

• PIC18F25K80 • PIC18LF25K80
• PIC18F26K80 • PIC18LF26K80
• PIC18F45K80 • PIC18LF45K80
• PIC18F46K80 • PIC18LF46K80
• PIC18F65K80 • PIC18LF65K80
• PIC18F66K80 • PIC18LF66K80

Below is the code I used to test. Without looking too deeply into the USART.H file and the PIC Datasheet, my guess is that the settings/formulas for the BRG in the USART.H file will need to be adapted to support this "family" of chips.

Complete ASM is attached:

GCB:

#chip 18F25K80, 32
#config XINST OFF
#config FOSC = INTIO2

#define USART_BAUD_RATE 9600
#define USART_BLOCKING

Dir PORTC.6 Out 'TX
Dir PortC.7 In  'RX

DO
    hserprint "UUUU"
    wait 10 ms
Loop

ASM CODE (USART SECTION)

  INITUSART
  ;SPBRG1 = SPBRGL_TEMP
    movlw   64
    movwf   SPBRG1,ACCESS
  ;SPBRGH1 = SPBRGH_TEMP
    movlw   3
    movwf   SPBRGH1,ACCESS
  ;BAUDCON1.BRG16 = BRG16_TEMP
    bsf BAUDCON1,BRG16,ACCESS
  ;TX1STA.BRGH = BRGH_TEMP
    bsf TX1STA,BRGH,BANKED
  ;Set SYNC1 Off
    bcf TXSTA,SYNC1,ACCESS
  ;Set SPEN1 On
    bsf RCSTA,SPEN1,ACCESS
  ;Set CREN1 On
    bsf RCSTA,CREN1,ACCESS
  ;Set TXEN1 On
    bsf TXSTA,TXEN1,ACCESS
    return

[William Roth]

This problem has been resolved in the latest USART.h file. The file can be downloaded at the link below.

https://sourceforge.net/p/gcbasic/code/HEAD/tree/GCBASIC/trunk/include/lowlevel/usart.h