Kevin:
Here are some change that I made to your serial routine to set the baudrate correctly for any processor speed.
in serial_port.c
#ifdef ENABLE_SERIAL_PORT_ONE
void Init_Serial_Port_One(void)
{
// Start by initializing the serial port with code
// common to receive and transmit functions
// SPBRG = BAUD_38400 ; // baud rate generator register [251]
SPBRG = SPBRG_VAL_1; // defined in hardware.h
//
#ifdef USART1_USE_BRGH_LOW
TXSTAbits.BRGH = 0; // high baud rate select bit (asynchronous mode only) [248]
#else // 0: low speed
TXSTAbits.BRGH = 1; // high baud rate select bit (asynchronous mode only) [248] // 1: high speed
#endif // 1: high speed
.................................................. .................................................. .................................................. ......
#ifdef ENABLE_SERIAL_PORT_TWO
void Init_Serial_Port_Two(void)
{
// Start by initializing the serial port with code
// common to receive and transmit functions
// SPBRG2 = BAUD_9600; // baud rate generator register [251]
SPBRG2 = SPBRG_VAL_2; // defined in hardware.h
//
#ifdef USART2_USE_BRGH_LOW
TXSTA2bits.BRGH = 0; // high baud rate select bit (asynchronous mode only) [248]
#else // 0: low speed
TXSTA2bits.BRGH = 1; // high baud rate select bit (asynchronous mode only) [248] // 1: high speed
#endif // 1: high speed
------------------------------------------------------------------------------------------------------------------------------------------------------------
in the hardware set up routines...
// Define system xtal/clock frequency
//
#define CLOCK_FREQ (40000000) // Frequency in Hz
#if defined(__18CXX) // All PIC18 processors
#include <p18cxxx.h>
#define INSTR_FREQ (CLOCK_FREQ/4) // PIC18 clock divider
#else
#error Unknown processor or processor not defined
#endif
// Set up serial port(s) baud rate
//
#define BAUD_RATE_1 (38400) // Serial port 1, bps
#define BAUD_RATE_2 (38400) // Serial Port 2, bps
// set as needed...
//#define USART1_USE_BRGH_LOW // for most lower baud rates
//#define USART2_USE_BRGH_LOW // for most lower baud rates
#if defined(USART1_USE_BRGH_LOW)
#define SPBRG_VAL_1 ( ((CLOCK_FREQ/BAUD_RATE_1)/64) - 1)
#else
#define SPBRG_VAL_1 ( ((CLOCK_FREQ/BAUD_RATE_1)/16) - 1)
#endif
#if defined(USART2_USE_BRGH_LOW)
#define SPBRG_VAL_2 ( ((CLOCK_FREQ/BAUD_RATE_2)/64) - 1)
#else
#define SPBRG_VAL_2 ( ((CLOCK_FREQ/BAUD_RATE_2)/16) - 1)
#endif
#if ((SPBRG_VAL_1 > 255) || (SPBRG_VAL_2 > 255))
#error "Calculated SPBRG value is out of range for current CLOCK_FREQ."
#endif