求一个使用内部振荡器的PIC24F工程

fengyunyu

第一次用PIC，网上找的例程都是使用外部晶振。哪位坛友给一个使用内部振荡器的PIC24F工程？需要开一个定时器，并定时改变某个IO口电平即可。

fengyunyu

在一网站看到的配置代码，不知道有无问题。

PIC24 clock setup

config word FOSCSEL selects which oscillator.
each oscillator option can be with or without PLL (which multiplies by 4)
The builtin RC oscillator is 8mhz, so
FNOSC_FRC is 8mhz, and FNOSC_FRCPLL is 32mhz.

THEN, there's a postscaler. CLKDIVbits.RCDIV sets the divide-by. 0 means
don't.

NOTE: The default setting of the postscaler is DIVIDE BY TWO. If you don't
want it to halve the clock freq, you have to set CLKDIVbits.RCDIV=0 early
in the program.

THEN, whatever the output of all the above, is divided by two.

For example
_FOSCSEL(FNOSC_FRC)
CLKDIVbits.RCDIV = 0;
gives the builtin 8mhz oscillator, not divided by a postscaler, and
finally divided by two = 4MHz.

_FOSCSEL(FNOSC_FRCPLL)
gives builtin 8mhz, times 4 (pll) = 32MHz, divided by 2 = 16 MHz.



UART BAUD RATE SETTINGS.

Builtin RC oscillator @ 8MHZ, PLL enabled, CLKDIV=0 = system clock at 16MHz

_FOSCSEL(FNOSC_FRCPLL)
CLKDIVbits.RCDIV = 0;
U1MODEbits.BRGH = 1;

9600bps: U1BRG=416
19200bps: U1BRG=207
38400bps: U1BRG=103
57600bps: U1BRG=70
115200bps: U1BRG=34

fengyunyu

找了一个

24F32KA301 Example LED Flash using Microchip C

Example program for the Microchip PIC 24F32KA301 using Microchip C compiler

Using Timer1 and interrupts, flashes LED on A0 once per second

       
/*
* Microchip C Compiler Demo Program for PIC24F32KA301
* PIC24F32KA301 flash LED on A0 using Timer1 and interrupts
* Copyright (C)2011 HobbyTronics.co.uk
* Freely distributable.
*/

//include basic header definition
#include <p24f32ka301.h>

//config
_FOSCSEL(FNOSC_FRCPLL & IESO_OFF);    // FRC Oscillator with PLL (32MHz)
_FOSC (FCKSM_CSDCMD & SOSCSEL1_SOSCLP & POSCFREQ_MS
       & OSCIOFNC_OFF & POSCMOD_NONE);  

/*Clock switching and Fail-Safe Clock monitor DISABLED
  Secondary Oscillator Select
  Primary Oscillator Frequency Range
  OSCO Pin Configuration OFF
  Oscillator Selection
*/

//prototypes
void timer1_init(void);

//main loop
int main(void)
{
   //Set up Clock
   OSCCON = 0x11C0;    // select INTERNAL FRC (32MHz), Post Scale & PLL
   CLKDIV = 0x0000;    // No clock Divide
   
   //Set Ports to Digital
   ANSELA=0x0000;
   ANSELB=0x0000;
   ANSELC=0x0000;
   TRISA=0x0000;
   LATAbits.LATA0 = 0;

   timer1_init();
   SRbits.IPL = 0 ;    // turn on all interrupt priorities
   
   //Loop forever
   while(1)
   {
   }
}

//Set up Timer, target 2Hz interrupts
void timer1_init(void)
{
   //Setup Timer1
   PR1 = 0x7A12;          // set for 2Hz (Clock is 32KHz/2 = 16MHz)
   IPC0bits.T1IP = 5;     //set interrupt priority
   T1CON = 0b1000000000110000;    //turn on the timer
   IFS0bits.T1IF = 0;     //reset interrupt flag
   IEC0bits.T1IE = 1;     //turn on the timer1 interrupt
}

//_T1Interrupt() is the T1 interrupt service routine (ISR).
void __attribute__((__interrupt__, auto_psv)) _T1Interrupt(void)
{
   LATAbits.LATA0 = ~LATAbits.LATA0;    //Toggle output to LED
   IFS0bits.T1IF = 0;
}

fengyunyu

//Set up Timer, target 2Hz interrupts
void timer1_init(void)
{
   //Setup Timer1
   PR1 = 0x7A12;          // set for 2Hz (Clock is 32KHz/2 = 16MHz)
   IPC0bits.T1IP = 5;     //set interrupt priority
   T1CON = 0b1000000000110000;    //turn on the timer
   IFS0bits.T1IF = 0;     //reset interrupt flag
   IEC0bits.T1IE = 1;     //turn on the timer1 interrupt
}

哪位坛友给解说下，2Hz是如何算出来的？

stanley.zhao

fengyunyu 发表于 2014-11-21 13:28
//Set up Timer, target 2Hz interrupts
void timer1_init(void)
{

资料都找到了，放到板子上实验下就好了，反正烧不坏芯片的。

void timer1_init(void)
{
   //Setup Timer1
   PR1 = 0x7A12;          // set for 2Hz (Clock is 32MHz/2 = 16MHz)
   IPC0bits.T1IP = 5;     //set interrupt priority
   T1CON = 0b1000000000110000;    //turn on the timer,bit5:bit4=11,时钟分频1:256
   IFS0bits.T1IF = 0;     //reset interrupt flag
   IEC0bits.T1IE = 1;     //turn on the timer1 interrupt
}

2Hz ，周期为0.5s=5000000us
0x7A12 = 31250
1/16*256*31250=5000000

LZ认真看DS，都是最基本的
看我这么仔细回答的份上，100分给我吧

fengyunyu

stanley.zhao 发表于 2014-11-21 13:50
资料都找到了，放到板子上实验下就好了，反正烧不坏芯片的。

void timer1_init(void)

谢谢解答。再请教下，MCLR有外接复位芯片，看网上有说不能直接用ICD或PICKIT烧写或仿真，是这样么？

stanley.zhao

fengyunyu 发表于 2014-11-21 13:58
谢谢解答。再请教下，MCLR有外接复位芯片，看网上有说不能直接用ICD或PICKIT烧写或仿真，是这样么？ ...

这个真心不清楚了 ，还是老话实验出真知！

nos002

#ifndef __p24FConfig_H
#define __p24FConfig_H

#include<p24Fxxxx.h>


_FBS
(
    BWRP_OFF &      // Boot Segment Write Protect (Disabled)
    BSS_OFF         // Boot segment Protect (No boot flash segment)
)

_FGS
(
    GWRP_OFF &      // General Segment Flash Write Protect (General segment may be written)
    GSS0_OFF        // General Segment Code Protect (No Protection)
)

_FOSCSEL
(
    FNOSC_FRCPLL &  // Oscillator Select
    SOSCSRC_DIG &   // SOSC Source Type (Analog Mode for use with crystal)
    LPRCSEL_HP &    // LPRC Power and Accuracy (High Power/High Accuracy)
    IESO_ON         // Internal External Switch Over bit (Internal External Switchover mode enabled (Two-speed Start-up enabled))
)

_FOSC
(
    POSCMD_NONE &     // Primary Oscillator Mode (Primary oscillator disabled)
    OSCIOFNC_OFF &   // CLKO Enable Configuration bit (CLKO output signal enabled)
    POSCFREQ_MS &    // Primary Oscillator Frequency Range Configuration bits (Primary oscillator/external clock frequency between 100kHz to 8MHz)
    SOSCSEL_SOSCLP & // SOSC Power Selection Configuration bits (Secondary Oscillator configured for high-power operation)
    FCKSM_CSDCMD     // Clock Switching and Monitor Selection (Clock Switching and Fail-safe Clock Monitor Enabled)
)

_FWDT
(
    WDTPS_PS2 & // Watchdog Timer Postscale Select bits (1:32768)
    FWPSA_PR32 &   // WDT Prescaler bit (WDT prescaler ratio of 1:128)
    FWDTEN_OFF &    // Watchdog Timer Enable bits (WDT disabled in hardware; SWDTEN bit disabled)
    WINDIS_OFF      // Windowed Watchdog Timer Disable bit (Standard WDT selected (windowed WDT disabled))
)


// Warning:
// Always enable MCLRE_ON config bit setting so that the MCLR pin function will
// work for low-voltage In-Circuit Serial Programming (ICSP). The Microstick
// programming circuitry only supports low-voltage ICSP. If you disable MCLR pin
// functionality, a high-voltage ICSP tool will be required to re-program the
// part in the future.
_FPOR
(
    BOREN_BOR3 &    // Brown-out Reset Enable bits (Enabled in hardware; SBOREN bit disabled)
    PWRTEN_ON &     // Power-up Timer Enable (PWRT enabled)
    I2C1SEL_PRI &   // Alternate I2C1 Pin Mapping bit (Default SCL1/SDA1 Pins for I2C1)
    BORV_V18 &      // Brown-out Reset Voltage bits (Brown-out Reset at 1.8V)
    MCLRE_ON        // MCLR Pin Enable bit (RA5 input disabled; MCLR enabled)
)

_FICD
(
    ICS_PGx2        // ICD Pin Placement Select (EMUC/EMUD share PGC3/PGD3)
)

#endif

nos002

/****************************************************************************************
*名 称：SYSYTEMInit
*参 数：
*返 回：
*说 明：设定各种初始用户参数
*****************************************************************************************/
void SYSTEMInit(void)
{
    OSCCON = 0;
    OSCCONbits.CLKLOCK = 0;
    OSCCONbits.LOCK = 1; //PLL模块锁定
    CLKDIVbits.RCDIV = 0b000; //内部时钟8M，1:1分频
    OSCCONbits.NOSC = 1;
    OSCCONbits.COSC = 1; //当前振荡器选择001，带后分频和4倍PLL模块的8M FRC振荡器
    U1MODEbits.UARTEN = 0;
    RCONbits.SWDTEN = 1;

}


/**************************************************************
* 名 称：T4Initial
* 参 数：
* 返 回：
* 说 明：定时5ms,Fosc=32M,指令周期等于Fosc/2,一次计时等于一个指令周期，
*        等于62.5ns，0.0625x78x16x16=1248us.
***************************************************************/
void T4Initial(void)
{
    //CORCON=0;
    //INTCON1=0x8000;
    //INTCON2=0x0000;
    TMR4 = 0;
    PR4 = 78;
    T4CON = 0x007e; //前分频1:16，后分频1:16
    IPC6bits.T4IP = 3;
    IFS1bits.T4IF = 0;
    IEC1bits.T4IE = 1;
    T4CONbits.TON = 1;
}

/**************************/
void IOInit(void)
{
    //AD1PCFG = 0xFFFF;
    ANSA = 0x0000; // Enable PORTA Digital Input Buffers
    ANSB = 0x0000; // Enable PORTB Digital Input Buffers

    ODCBbits.ODB8 = 1;
    ODCBbits.ODB9 = 1;

    LATA = 0xffa3; //RA0低电平驱动buzzer，设为高电平；RA2:3为晶振脚，晶振未接，设为低电平
    LATB = 0x0300; //RB8:9 为键盘扫描口，设高电平，其他设为低电平
    TRISA = 0xffa2;//RA1为ADC输入
    TRISB = 0x00f2;//RB1为 U2RX、RB4:7为键盘输入口，设为输入
}
/********************************************************************************************
* 名 称：main
* 参 数：
* 返 回：
* 说 明：
*********************************************************************************************/
int main(void)
{
    SYSTEMInit();
    IOInit();
    T4Initial();
    while(1);
}
/*************************************************************************************
* 名 称：T4中断
* 参 数：
* 返 回：
* 说 明：1.25ms中断，产生1.25ms和5ms嘀嗒信号，1.25ms作为数码动态显示时基，5ms作为键盘等时基
*************************************************************************************/
void __attribute__((interrupt, shadow, auto_psv))_T4Interrupt()
{
    static unsigned char i;
    IFS1bits.T4IF = 0;
    GLOBALbits.Tick1ms = 1;
    if (3 < i++)//4*1.25=5ms
    {
        i = 0;
        GLOBALbits.Tick5ms = 1;
    }
    //return ReceiveDataServer(Uart2RBuf);
}