PIC32延时程序

2万 · 2020-9-3 21:29

据说PIC32单片机的延时，可以用内部计数器进行延时。我想延时2us，但是，死活都不能达到2us

1万 · 2020-9-3 21:33

示波器显示多少

2万 · 2020-9-3 21:36

示波器显示是40us。示波器用的是虚拟示波器。系统时钟是40Mhz

2万 · 2020-9-3 21:40

也就是说，当我用 delay_us(2) 的时候，虚拟示波器显示的时间是 40us。还是说，必须用定时器才能达到1us的延时？

2万 · 2020-9-3 21:45

怎么才能如同STM32单片机那样，可以实现1uS啊？

只看该作者 · 2020-9-3 21:49

自己写，自己调

2万 · 2020-9-3 21:51

楼主程序可以公开吗？贴程序看下吧，这么说看不出什么原因

2万 · 2020-9-3 21:59

#define SYSCLK_FREQUENCY    40000000    //* 200MHz，修改成你自己的系统时钟
#define PBCLK7_FREQUENCY       SYSCLK_FREQUENCY
#define CORE_TIMER_FREQUENCY       (PBCLK7_FREQUENCY / 2)
#define CORE_TIMER_MILLISECONDS    (CORE_TIMER_FREQUENCY / 100)
#define CORE_TIMER_MICROSECONDS    (CORE_TIMER_FREQUENCY / 10000)

unsigned int __attribute__((nomips16)) ReadCoreTimer(void)
{
unsigned int timer;

asm volatile("mfc0 %0, $9" : "=r"(timer));

return timer;
}

void delay_us(unsigned int delayUs)
{
unsigned int delayStart;

delayStart = ReadCoreTimer();
while ((ReadCoreTimer() - delayStart) < (delayUs * CORE_TIMER_MICROSECONDS));
}

void delay_ms(unsigned int delayUs)
{
unsigned int delayStart;

delayStart = ReadCoreTimer();
while ((ReadCoreTimer() - delayStart) < (delayUs * CORE_TIMER_MILLISECONDS));
}

2万 · 2020-9-3 22:02

配置位设置?

2万 · 2020-9-3 22:06

/******************* 配置位设置 ******************************/
// DEVCFG3
// USERID = No                                                          //Setting

#pragma config FSRSSEL = PRIORITY_7                // SRS Select (SRS Priority 7)
#pragma config FMIIEN = OFF                               // Ethernet RMII/MII Enable (RMII Enabled)
#pragma config FETHIO = OFF                            // Ethernet I/O Pin Select (Alternate Ethernet I/O)
#pragma config FCANIO = OFF                            // CAN I/O Pin Select (Alternate CAN I/O)
#pragma config FUSBIDIO = ON                            // USB USID Selection (Controlled by the USB Module)
#pragma config FVBUSONIO = ON                      // USB VBUS ON Selection (Controlled by USB Module)

// DEVCFG2
#pragma config FPLLIDIV = DIV_2                      // PLL Input Divider (2x Divider)
#pragma config FPLLMUL = MUL_20                // PLL Multiplier (20x Multiplier)
#pragma config UPLLIDIV = DIV_1                   // USB PLL Input Divider (12x Divider)
#pragma config UPLLEN = OFF                         // USB PLL Enable (Disabled and Bypassed)
#pragma config FPLLODIV = DIV_2                   // System PLL Output Clock Divider (PLL Divide by 1)
                                                                        // SYSCLK = (8MHz Crystal/ FPLLIDIV * FPLLMUL / FPLLODIV)=40M
// DEVCFG1
#pragma config FNOSC = PRIPLL                   // Oscillator Selection Bits (Fast RC Osc with PLL)
#pragma config FSOSCEN = ON                      // Secondary Oscillator Enable (Disabled)
#pragma config IESO = ON                            // Internal/External Switch Over (Disabled)
#pragma config POSCMOD = HS                   // Primary Oscillator Configuration (HS osc mode)
#pragma config OSCIOFNC = OFF                // CLKO Output Signal Active on the OSCO Pin (Disabled)
#pragma config FPBDIV = DIV_1                   // Peripheral Clock Divisor (Pb_Clk is Sys_Clk/8)=5M
#pragma config FCKSM = CSDCMD             // Clock Switching and Monitor Selection (Clock Switch Disable, FSCM Disabled)
#pragma config WDTPS = PS1                      // Watchdog Timer Postscaler (1:1)
#pragma config FWDTEN = OFF                   // Watchdog Timer Enable (WDT Disabled (SWDTEN Bit Controls))

// DEVCFG0
#pragma config DEBUG = ON                      // Background Debugger Enable (Debugger is enabled)
#pragma config ICESEL = ICS_PGx1          // ICE/ICD Comm Channel Select (ICE EMUC1/EMUD1 pins shared with PGC1/PGD1)
#pragma config PWP = PWP512K                // Program Flash Write Protect (First 512K)
#pragma config BWP = ON                         // Boot Flash Write Protect bit (Protection Enabled)
#pragma config CP = ON                            // Code Protect (Protection Enabled)

//*************** 宏定义 *******************************************************

2万 · 2020-9-3 22:11

2us为何延时不了？
你心理没数啊？

1万 · 2020-9-3 22:15

你操作配置单时间都超过2us
这种直接用软延时就行了。

2万 · 2020-9-3 22:18

大神，软延时怎么弄？求指教
能发个例程吗？

1万 · 2020-9-3 22:20

问题贴里带有芯片完整型号、系统配置（尤其时钟），最好有完整工程，这样应该能更好的帮助你。

1万 · 2020-9-3 22:23

从你的信息看，40MHz系统频率，按Core timer为系统时钟除以2，那么1us就，20个core timer周期(40个指令周期)，2us也就是80个指令周期；函数进出需要的时间需要剔除才能得到精准时间，所以应该输入参数需要微调才能准确。

2万 · 2020-9-3 22:29

不过你的测试相差太大，更多应该是时钟配置可能不对导致。

2万 · 2020-9-3 22:33

调一个库函数都超过这个时间了

2万 · 2020-9-3 22:41

芯片型号是PIC32MX795F512L ，晶振是8M。

2万 · 2020-9-3 22:46

/******************* 配置位设置 ******************************/
// DEVCFG3
// USERID = No //Setting

#pragma config FSRSSEL = PRIORITY_7    // SRS Select (SRS Priority 7)
#pragma config FMIIEN = OFF          // Ethernet RMII/MII Enable (RMII Enabled)
#pragma config FETHIO = OFF          // Ethernet I/O Pin Select (Alternate Ethernet I/O)
#pragma config FCANIO = OFF          // CAN I/O Pin Select (Alternate CAN I/O)
#pragma config FUSBIDIO = ON          // USB USID Selection (Controlled by the USB Module)
#pragma config FVBUSONIO = ON          // USB VBUS ON Selection (Controlled by USB Module)

// DEVCFG2
#pragma config FPLLIDIV = DIV_2       // PLL Input Divider (2x Divider)
#pragma config FPLLMUL = MUL_20       // PLL Multiplier (20x Multiplier)
#pragma config UPLLIDIV = DIV_1       // USB PLL Input Divider (12x Divider)
#pragma config UPLLEN = OFF          // USB PLL Enable (Disabled and Bypassed)
#pragma config FPLLODIV = DIV_2       // System PLL Output Clock Divider (PLL Divide by 1)
                                    // SYSCLK = (8MHz Crystal/ FPLLIDIV * FPLLMUL / FPLLODIV)=40M
// DEVCFG1
#pragma config FNOSC = PRIPLL          // Oscillator Selection Bits (Fast RC Osc with PLL)
#pragma config FSOSCEN = ON          // Secondary Oscillator Enable (Disabled)
#pragma config IESO = ON             // Internal/External Switch Over (Disabled)
#pragma config POSCMOD = HS          // Primary Oscillator Configuration (HS osc mode)
#pragma config OSCIOFNC = OFF          // CLKO Output Signal Active on the OSCO Pin (Disabled)
#pragma config FPBDIV = DIV_1          // Peripheral Clock Divisor (Pb_Clk is Sys_Clk/8)=5M
#pragma config FCKSM = CSDCMD          // Clock Switching and Monitor Selection (Clock Switch Disable, FSCM Disabled)
#pragma config WDTPS = PS1             // Watchdog Timer Postscaler (1:1)
#pragma config FWDTEN = OFF          // Watchdog Timer Enable (WDT Disabled (SWDTEN Bit Controls))

// DEVCFG0
#pragma config DEBUG = ON             // Background Debugger Enable (Debugger is enabled)
#pragma config ICESEL = ICS_PGx1       // ICE/ICD Comm Channel Select (ICE EMUC1/EMUD1 pins shared with PGC1/PGD1)
#pragma config PWP = PWP512K          // Program Flash Write Protect (First 512K)
#pragma config BWP = ON                // Boot Flash Write Protect bit (Protection Enabled)
#pragma config CP = ON                // Code Protect (Protection Enabled)

//*************** 宏定义 *******************************************************

2万 · 2020-9-3 22:49

有没有其他方式能延时us级别的？