18F26k22优先中断和UART的神秘行为复位？

您好，我有一小部分代码，我只是为了测试优先级中断。PIC:18F26K22，内部OSC32 MHz（8xPLL），没有WDT。中断使用：time0（高优先级），USAT RX（低优先级）。Usart：9600 8N1。编译器：XC8 1.37免费模式，MPLAX 3.25 PIC是回声前夕。Ry接收到的字符，以前存储在环形缓冲区中。定时器0中断只是为了测试优先级系统，它比USAT快（这里的定时器溢出并不重要）。PIC正在正确地接收数据（不管使用内部振荡器，没有影响它的漂移），Time0正在正确地触发中断。一切看起来都很好，但是…如果你键入终端，在某些时候你会注意到PIC看起来像重新启动。这种“重置”是随机发生的。当你打字或输入一堆数据后，有时会发生，但它会在某个时候发生。您看到的是“等待输入数据…”（检查代码）。我检查了RCON和STKPTR，寻找可能的复位源，但没有复位的原因。我在数据表中读到，对于低中断上下文不保存，必须在软但XC8编译器手册中完成。正如我所理解的那样，编译器生成用于保存和恢复高优先级和低优先级中断的上下文的代码。我检查了高处，有一堆寄存器被保存，对于低我可以看到一些寄存器被保存和恢复，但我不确定他们是否应该是他们应该是什么。代码以防万一：配置：我试图找到有关的问题在论坛上，但没有找到任何…我不KNO。确切地说，正在发生什么，我的疑虑是关于上下文的，但是我不确定编译器在做什么（或者没有做什么）。有什么想法或建议吗？干杯。



      以下为原文

    Hello.

I'm having some troubles with a small piece of code I made just for testing the priority interrupts.

PIC: 18F26k22, Internal Osc 32Mhz (8xPLL), No WDT.
Interrupts used: Timer0 (high priority), Usart RX (low priority).
Usart: 9600 8N1.
Compiler: XC8 1.37 Free mode, MPLAX 3.25

The PIC is echoing every received character,  previously stored in a ring buffer. Timer 0 interrupt is there just to test the priority system, it's faster than the usart (timer overflow is not important here). PIC is receiving data correctly (regardless using the internal oscillator, there is no drift affecting it), Timer0 is triggering interrupt correctly. Everything looks ok, but ...  if you type in the terminal, in some point you notice the PIC look like restarting.
This kind of "reset" happens randomly... sometimes happens as soon as you type something or after typing a bunch of data, but it will happen in some point... And what you see is again the  "Waiting for incoming data..." (check code).

I checked the RCON and STKPTR looking for a possible source of reset, but there is no cause of reset.
I read in datasheet that for low interrupt context is not saved and must be done in soft, but XC8 compiler's manual -as far as i understood- says the compiler generate code for saving/restoring the context for both high and low priority interrupts. I checked the high and there's a bunch of registers being saved, and for low I could see some registers being saved and restored but I'm not sure if they are all that they should be.

Code just in case:

void main(void)
{
  ConfigureOscillator(); //Fosc 32Mhz, from internal osc with PLL... 125ns cycle. Verified.
         
  InitApp(); // usual, setting tris registers, all pins digital, no comparators... bla bla.. Verified
              
  //configure EUSART 16-bit mode
  BAUDCON1 = 0b01001000;
  //open USART 9600 8N1, RX int on
  Open1USART (USART_TX_INT_OFF &
             USART_RX_INT_ON &
             USART_ASYNCH_MODE &
             USART_EIGHT_BIT &
             USART_CONT_RX &
             USART_BRGH_HIGH, 64);
  SPBRGH1 = 3;  //all ok here

  //enable priorities
  RCONbits.IPEN = 1;
  

  //enable USART interrupts
  PIR1bits.RC1IF = 0; //reset RX pin flag
  IPR1bits.RC1IP = 0; //no high priority
  PIE1bits.RC1IE = 1; //RX int enabled
  
  //configure TIMER0
  T0CONbits.TMR0ON=1; //enable TMR0
  T0CONbits.T08BIT=1; //8-bit mode
  T0CONbits.T0CS=0; //use internal clock
  T0CONbits.PSA=0; //no prescaler
  //enable TIMER0 interrupts
  INTCONbits.TMR0IF = 0; //clear flag
  INTCON2bits.TMR0IP = 1; //tmr0 high priority int
  INTCONbits.TMR0IE = 1; //tmr0 int enable
  
  //enable high/low priority interrupts
  INTCONbits.GIEH = 1;
  INTCONbits.GIEL = 1;

  putrs1USART("Waiting for incoming data...nr");

  while(1)
  {
    PIE1bits.RC1IE = 0; //disable RX interrupt for accessing critical resource
    int data = rx_buffer_get();
    PIE1bits.RC1IE = 1; //re-enable RX interrupt
   
    if (data != SERIAL_BUFFER_EMPTY) {
      while( Busy1USART() );
      putc1USART((unsigned char)data);
    }
  }
}



void interrupt low_priority usart_rx_isr()
{      
  if ( PIR1bits.RC1IF ) {

    //store incoming data into buffer, no Frame/Overrun check for our human-speed test
    rx_buffer_put(RCREG1);
  }
}

volatile char timer = 0; //for testing

void interrupt high_priority timer0_isr()
{
  if ( INTCONbits.TMR0IF ) {
    //do not reload timer, let it overflow.
    timer = ~timer;
    INTCONbits.TMR0IF = 0; //clear flag
  }  
}


Config:

// CONFIG1H
#pragma config FOSC = INTIO67 // Oscillator Selection bits (Internal oscillator block)
#pragma config PLLCFG = ON
#pragma config PRICLKEN = ON // Primary clock enable bit (Primary clock enabled)
#pragma config FCMEN = OFF // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = OFF // Internal/External Oscillator Switchover bit (Oscillator Switchover mode disabled)

// CONFIG2L
#pragma config PWRTEN = OFF // Power-up Timer Enable bit (Power up timer disabled)
#pragma config BOREN = SBORDIS // Brown-out Reset Enable bits (Brown-out Reset enabled in hardware only (SBOREN is disabled))
#pragma config BORV = 190 // Brown Out Reset Voltage bits (VBOR set to 1.90 V nominal)

// CONFIG2H
#pragma config WDTEN = OFF // Watchdog Timer Enable bits (WDT is always enabled. SWDTEN bit has no effect)
#pragma config WDTPS = 32768 // Watchdog Timer Postscale Select bits (1:32768)

// CONFIG3H
#pragma config CCP2MX = PORTC1 // CCP2 MUX bit (CCP2 input/output is multiplexed with RC1)
#pragma config PBADEN = OFF // PORTB A/D Enable bit (PORTB<5:0> pins are configured as digital I/O on Reset)
#pragma config CCP3MX = PORTB5 // P3A/CCP3 Mux bit (P3A/CCP3 input/output is multiplexed with RB5)
#pragma config HFOFST = ON // HFINTOSC Fast Start-up (HFINTOSC output and ready status are not delayed by the oscillator stable status)
#pragma config T3CMX = PORTC0 // Timer3 Clock input mux bit (T3CKI is on RC0)
#pragma config P2BMX = PORTB5 // ECCP2 B output mux bit (P2B is on RB5)
#pragma config MCLRE = EXTMCLR // 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 LVP = ON // Single-Supply ICSP Enable bit (Single-Supply ICSP enabled if MCLRE is also 1)
#pragma config XINST = OFF // Extended Instruction Set Enable bit (Instruction set extension and Indexed Addressing mode disabled (Legacy mode))


void ConfigureOscillator()
{
  OSCCONbits.IRCF = 0x6; //Configure internal clock frequency: 8Mhz
  OSCCONbits.SCS = 0x0;
  OSCTUNEbits.PLLEN = 1;
  // MPLABX is waiting forever here, HFIOFS is always 0!!
  while (!OSCCONbits.HFIOFS);
}
I tried to find something about related issues in the forum but didnt find any...
I don't know exactly what is happening, my suspects are about the context but I'm not sure about what the compiler is doing (or not doing).

Any idea or suggestion?

Cheers.