求一个使用内部振荡器的PIC24F工程
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。 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 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;
} //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？ 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{:lol:} 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？ 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{:sad:} ，还是老话实验出真知！{:lol:} #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 本帖最后由 nos002 于 2014-12-2 18:48 编辑
/****************************************************************************************
*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);
}
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