PIC18F4520串口收发字符长度有限制

只看该作者 · 2015-12-11 09:52

本帖最后由 lcy89815 于 2015-12-11 09:52 编辑

这两天在试PIC18F4520串口自动收发功能，发现在串口调试小助手只能发送28个以内的字符，超过的只能显示前28个，之后就无法接收，这会是什么原因造成的呢,谢谢大家了！

void main(void)
{
OSCCON = 0x72;             //8MHz,Internal oscillator, however its actual value is 0x76
/*16-bit,asynchronous mode, desired baud rate = Fosc / (4 * ([SPBRGH:SPBRGL] + 1))*/
SYNC = 0;                      //asynchronous mode
BRG16 = 1;                   //16-bit baud rate generator is used
BRGH = 1;                      //high speed
SPBRGH = 0x00;          //baud rate 9600
SPBRG = 0xcf;
/*enable receiver*/
SPEN = 1;                      //enable eusart
TRISC6 = 1;
TRISC7 = 1;
CREN = 1;                   //enable receiver circuitry of eusart
TXEN = 1;                   //enable transmitter circuitry of eusart
RCIE = 1;                      //enable usart receiver interrupt

GIE = 1;                      //enable all active interrupts
PEIE = 1;                   //enable all active peripheral interrupts

while(1)
{
      ;
}
return;
}
void interrupt INT_ISR(void)
{
if(RCIF && RCIE)
{
   TXREG = RCREG;
   while(!TRMT);
}
}

只看该作者 · 2015-12-11 10:08

RCIF要零吧。

只看该作者 · 2015-12-11 10:10

印象中。PIC单片机在串口通信错误时（溢出、检验等），串口会停止工作。需要处理串口错误中断，重新初始化一下。

你检查一下串口状态寄存器看看。

只看该作者 · 2015-12-11 10:16

perry_peng 发表于 2015-12-11 10:08
RCIF要零吧。

RCIF是只读位，不需要清零吧

只看该作者 · 2015-12-11 10:40

shaoziyang 发表于 2015-12-11 10:10
印象中。PIC单片机在串口通信错误时（溢出、检验等），串口会停止工作。需要处理串口错误中断，重新初始化 ...

查看了一下，帧错误位FERR，和溢出错误位OERR都为零，没有出错呀

只看该作者 · 2015-12-11 11:07

shaoziyang 发表于 2015-12-11 10:10
印象中。PIC单片机在串口通信错误时（溢出、检验等），串口会停止工作。需要处理串口错误中断，重新初始化 ...

仿真中的确没观测到OERR置1，尝试增加溢出处理，情况改善不少，但发现字符w一直丢失同时误码率很高，进一步该如何处理好呢
void interrupt INT_ISR(void)
{
if(RCIF && RCIE)
{
      if(OERR)
      {
         CREN = 0;
      }
      CREN = 1;
      TXREG = RCREG;
      while(!TRMT);
}
}

只看该作者 · 2015-12-11 14:30

lcy89815 发表于 2015-12-11 11:07
仿真中的确没观测到OERR置1，尝试增加溢出处理，情况改善不少，但发现字符w一直丢失同时误码率很高，进一 ...

是不是用RC振荡器，误差有点大？

只看该作者 · 2015-12-11 14:35

shaoziyang 发表于 2015-12-11 14:30
是不是用RC振荡器，误差有点大？

首先多谢shaoziyang的耐心解答，我采用的是内部振荡器。
配置位如下：
#include<pic18f4520.h>
#include <xc.h>

// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.

// CONFIG1H
#pragma config OSC = INTIO67 // Oscillator Selection bits (Internal oscillator block, port function on RA6 and RA7)
#pragma config FCMEN = ON    // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor enabled)
#pragma config IESO = OFF    // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)

// CONFIG2L
#pragma config PWRT = ON       // Power-up Timer Enable bit (PWRT enabled)
#pragma config BOREN = ON    // Brown-out Reset Enable bits (Brown-out Reset enabled and controlled by software (SBOREN is enabled))
#pragma config BORV = 2       // Brown Out Reset Voltage bits ()

// CONFIG2H
#pragma config WDT = OFF       // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDTPS = 32768 // Watchdog Timer Postscale Select bits (1:32768)

// CONFIG3H
#pragma config CCP2MX = PORTC // CCP2 MUX bit (CCP2 input/output is multiplexed with RC1)
#pragma config PBADEN = ON    // PORTB A/D Enable bit (PORTB<4:0> pins are configured as analog input channels on Reset)
#pragma config LPT1OSC = OFF // Low-Power Timer1 Oscillator Enable bit (Timer1 configured for higher power operation)
#pragma config MCLRE = ON    // MCLR Pin Enable bit (MCLR pin enabled; RE3 input pin disabled)

// CONFIG4L
//#pragma config STVREN = ON    // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config STVREN = OFF
#pragma config LVP = OFF       // Single-Supply ICSP Enable bit (Single-Supply ICSP disabled)
#pragma config XINST = OFF    // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))

// CONFIG5L
#pragma config CP0 = OFF       // Code Protection bit (Block 0 (000800-001FFFh) not code-protected)
#pragma config CP1 = OFF       // Code Protection bit (Block 1 (002000-003FFFh) not code-protected)
#pragma config CP2 = OFF       // Code Protection bit (Block 2 (004000-005FFFh) not code-protected)
#pragma config CP3 = OFF       // Code Protection bit (Block 3 (006000-007FFFh) not code-protected)

// CONFIG5H
#pragma config CPB = OFF       // Boot Block Code Protection bit (Boot block (000000-0007FFh) not code-protected)
#pragma config CPD = OFF       // Data EEPROM Code Protection bit (Data EEPROM not code-protected)

// CONFIG6L
#pragma config WRT0 = OFF    // Write Protection bit (Block 0 (000800-001FFFh) not write-protected)
#pragma config WRT1 = OFF    // Write Protection bit (Block 1 (002000-003FFFh) not write-protected)
#pragma config WRT2 = OFF    // Write Protection bit (Block 2 (004000-005FFFh) not write-protected)
#pragma config WRT3 = OFF    // Write Protection bit (Block 3 (006000-007FFFh) not write-protected)

// CONFIG6H
#pragma config WRTC = OFF    // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) not write-protected)
#pragma config WRTB = OFF    // Boot Block Write Protection bit (Boot block (000000-0007FFh) not write-protected)
#pragma config WRTD = OFF    // Data EEPROM Write Protection bit (Data EEPROM not write-protected)

// CONFIG7L
#pragma config EBTR0 = OFF    // Table Read Protection bit (Block 0 (000800-001FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF    // Table Read Protection bit (Block 1 (002000-003FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF    // Table Read Protection bit (Block 2 (004000-005FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF    // Table Read Protection bit (Block 3 (006000-007FFFh) not protected from table reads executed in other blocks)

// CONFIG7H
#pragma config EBTRB = OFF    // Boot Block Table Read Protection bit (Boot block (000000-0007FFh) not protected from table reads executed in other blocks)