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app026-3 UART 115200 baud rate

新會員

我測試 9600 ok 可是115200不行，請問有什麼要注意的嗎?
// JTAG/Code Protect/Write Protect/Clip-on Emulation mode
// Watchdog Timer/ICD pins select
_CONFIG1(JTAGEN_OFF & GCP_OFF & GWRP_OFF & COE_OFF & FWDTEN_OFF & ICS_PGx2)
// Disable CLK switch and CLK monitor, OSCO or Fosc/2, HS oscillator,
// Primary oscillator
_CONFIG2(FCKSM_CSDCMD & OSCIOFNC_OFF & POSCMOD_XT & FNOSC_PRI)

UARTInit()
{
TRISFbits.TRISF3 = 0;

// This is an EXAMPLE, so brutal typing goes into explaining all bit sets

//********************************************************************************
// STEP 1: configure U1MODE
// No Flow Control Mode, No Loop-Back
// No Auto-Baud, No Rx-Inversion
// Low BaudRate,
// 8-bit with no parity
// 1 Stop-bit
// bit 14, bit 10 no use
//********************************************************************************/

U1MODEbits.UARTEN = 0; // Bit15 TX, RX DISABLED, ENABLE at end of func
//= 0; // Bit14 no use
U1MODEbits.USIDL = 0; // Bit13 Continue in Idle
U1MODEbits.IREN = 0; // Bit12 No IR translation

U1MODEbits.RTSMD = 0; // Bit11 Simplex Mode
//= 0; // Bit10 no use
U1MODEbits.UEN = 0; // Bits8,9 TX,RX enabled, CTS,RTS not

U1MODEbits.WAKE = 0; // Bit7 No Wake up (since we don't sleep here)
U1MODEbits.LPBACK = 0; // Bit6 No Loop Back
U1MODEbits.ABAUD = 0; // Bit5 No Autobaud (would require sending '55')
U1MODEbits.RXINV = 0; // Bit4 IdleState = 1

U1MODEbits.BRGH = 0; // Bit3 16 clocks per bit period
U1MODEbits.PDSEL = 0; // Bits1,2 8bit, No Parity
U1MODEbits.STSEL = 0; // Bit0 One Stop Bit

//********************************************************************************
// STEP 2:
// Load the count to get 300 baudrate
// BRG = Fcy/(16*BaudRate)-1 where Fcy = Fosc/2 = 4MHz
//********************************************************************************/
U1BRG = 0x01; //0x19;

//********************************************************************************
// STEP 3:
// Tx Interrupt to interrupt when at least one location is free in Tx buffer
// No Tx Inversion, Disable Sync Break
// Enable Transmit, Disable Address Detect
// Interrupt on every receive.
// bit 12 no use
//********************************************************************************/

U1STAbits.UTXISEL1 = 0; //Bit15 Int when Char is transferred (1/2 config!)
U1STAbits.UTXINV = 0; //Bit14 N/A, IRDA config
U1STAbits.UTXISEL0 = 0; //Bit13 Other half of Bit15
//= 0; //bit 12 no use

U1STAbits.UTXBRK = 0; //Bit11 Disabled
U1STAbits.UTXEN = 0; //Bit10 TX pins controlled by UART1
U1STAbits.UTXBF = 0; //Bit9 *Read Only Bit*
U1STAbits.TRMT = 0; //Bit8 *Read Only bit*

U1STAbits.URXISEL = 0; //Bits6,7 Int. on character recieved
U1STAbits.ADDEN = 0; //Bit5 Address Detect Disabled
U1STAbits.RIDLE = 0; //Bit4 *Read Only Bit*

U1STAbits.PERR = 0; //Bit3 *Read Only Bit*
U1STAbits.FERR = 0; //Bit2 *Read Only Bit*
U1STAbits.OERR = 0; //Bit1 *Read Only Bit*
U1STAbits.URXDA = 0; //Bit0 *Read Only Bit*

IFS0bits.U1TXIF = 0; // Clear the Transmit Interrupt Flag
IEC0bits.U1TXIE = 0; // Enable Transmit Interrupts
IFS0bits.U1RXIF = 0; // Clear the Recieve Interrupt Flag
IEC0bits.U1RXIE = 1; // Enable Recieve Interrupts

U1MODEbits.UARTEN = 1; // And turn the peripheral on
U1STAbits.UTXEN = 1;
}

發表於: 2009/7/7 16:30