在用Nios II做外設時序驅動的時候，經常會用延時函數。有時會常使用某個FPGA芯片和時鐘，比如筆者一直使用的芯片是cyclone系列 EP2C35F484C8N，PLL輸入SOPC時鐘是50M。因此，提前測試硬件運行延時情況並編寫今後常用的延時函數有一定的意義。
軟件：Quartus II 9.0, Nios II 9.0
軟件：Quartus II 9.0, Nios II 9.0
硬件配置：
1、 在SOPC中調用Interval Timer核
圖 1 調用Interval Timer核
2、配置Interval Time
圖 2 Interval Timer參數配置
各參數說明請參照Quartus II Handbook Version 9.0 Volume 5: Embedded Peripherals, Chapter 24: Interval Timer Core.請根據需要進行設置。
3、更改核的名稱
該名稱可以按照自己的習慣取名。
圖 3 更改核的名稱
4、生成SOPC系統後，要在Nios II中進行設置。右擊工程名->System Library Properties-> system library->Timestamp timer
圖 4 Nios II設置
5、完成Nios II設置後，編譯。
軟件編程
參考Nios II Software Developer’s Handbook
例程：
#include <stdio.h> //printf()
#include <unistd.h> //usleep()
#include "system.h"
#include <sys/alt_timestamp.h> //timestamp
#include "alt_types.h"
#include <unistd.h> //usleep()
#include "system.h"
#include <sys/alt_timestamp.h> //timestamp
#include "alt_types.h"
void Delay0(unsigned long m)
{
usleep(m);
}
void Delay1(unsigned long n)
{
for(;n>0;n--);
}
{
usleep(m);
}
void Delay1(unsigned long n)
{
for(;n>0;n--);
}
void Delay2(unsigned long p)
{
while(--p);
}
{
while(--p);
}
int main(void)
{
alt_u32 t0,t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16,
t17,t18,t19,t20,t21,t22,t23,t24,t25,t26,t27,t28,t29,t30,t31,t32,t33,
t34,t35,t36,t37,t38,t39,t40,t41,t42,t43,t44,t45,t46,t47,t48,t49,t50,
freq;
{
alt_u32 t0,t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16,
t17,t18,t19,t20,t21,t22,t23,t24,t25,t26,t27,t28,t29,t30,t31,t32,t33,
t34,t35,t36,t37,t38,t39,t40,t41,t42,t43,t44,t45,t46,t47,t48,t49,t50,
freq;
if(alt_timestamp_start()<0) //啓動timestampe的計數
{
printf("No timestamp device available\n");
}
else
{
//usleep
t0 = alt_timestamp(); // 測量時間戳t0
Delay0(1);
t1 = alt_timestamp(); // 測量時間戳t1
Delay0(4);
t2 = alt_timestamp(); // 測量時間戳t2
Delay0(7);
t3 = alt_timestamp(); // 測量時間戳t3
Delay0(10);
t4 = alt_timestamp(); // 測量時間戳t4
Delay0(40);
t5 = alt_timestamp(); // 測量時間戳t5
Delay0(70);
t6 = alt_timestamp(); // 測量時間戳t6
Delay0(100);
t7 = alt_timestamp(); // 測量時間戳t7
Delay0(400);
t8 = alt_timestamp(); // 測量時間戳t8
Delay0(700);
t9 = alt_timestamp(); // 測量時間戳t9
Delay0(1000);
t10 = alt_timestamp(); // 測量時間戳t10
Delay0(4000);
t11 = alt_timestamp(); // 測量時間戳t11
Delay0(7000);
t12 = alt_timestamp(); // 測量時間戳t12
Delay0(10000);
t13 = alt_timestamp(); // 測量時間戳t13
Delay0(40000);
t14 = alt_timestamp(); // 測量時間戳t14
Delay0(70000);
t15 = alt_timestamp(); // 測量時間戳t15
Delay0(100000);
t16 = alt_timestamp(); // 測量時間戳t16
//for
t17 = alt_timestamp(); // 測量時間戳t17
Delay1(1);
t18 = alt_timestamp(); // 測量時間戳t18
Delay1(4);
t19 = alt_timestamp(); // 測量時間戳t19
Delay1(7);
t20 = alt_timestamp(); // 測量時間戳t20
Delay1(10);
t21 = alt_timestamp(); // 測量時間戳t21
Delay1(40);
t22 = alt_timestamp(); // 測量時間戳t22
Delay1(70);
t23 = alt_timestamp(); // 測量時間戳t23
Delay1(100);
t24 = alt_timestamp(); // 測量時間戳t24
Delay1(400);
t25 = alt_timestamp(); // 測量時間戳t25
Delay1(700);
t26 = alt_timestamp(); // 測量時間戳t26
Delay1(1000);
t27 = alt_timestamp(); // 測量時間戳t27
Delay1(4000);
t28 = alt_timestamp(); // 測量時間戳t28
Delay1(7000);
t29 = alt_timestamp(); // 測量時間戳t29
Delay1(10000);
t30 = alt_timestamp(); // 測量時間戳t30
Delay1(40000);
t31 = alt_timestamp(); // 測量時間戳t31
Delay1(70000);
t32 = alt_timestamp(); // 測量時間戳t32
Delay1(100000);
t33 = alt_timestamp(); // 測量時間戳t33
//while
t34 = alt_timestamp(); // 測量時間戳t34
Delay2(1);
t35 = alt_timestamp(); // 測量時間戳t35
Delay2(4);
t36 = alt_timestamp(); // 測量時間戳t36
Delay2(7);
t37 = alt_timestamp(); // 測量時間戳t37
Delay2(10);
t38 = alt_timestamp(); // 測量時間戳t38
Delay2(40);
t39 = alt_timestamp(); // 測量時間戳t39
Delay2(70);
t40 = alt_timestamp(); // 測量時間戳t40
Delay2(100);
t41 = alt_timestamp(); // 測量時間戳t41
Delay2(400);
t42 = alt_timestamp(); // 測量時間戳t42
Delay2(700);
t43 = alt_timestamp(); // 測量時間戳t43
Delay2(1000);
t44 = alt_timestamp(); // 測量時間戳t44
Delay2(4000);
t45 = alt_timestamp(); // 測量時間戳t45
Delay2(7000);
t46 = alt_timestamp(); // 測量時間戳t46
Delay2(10000);
t47 = alt_timestamp(); // 測量時間戳t47
Delay2(40000);
t48 = alt_timestamp(); // 測量時間戳t48
Delay2(70000);
t49 = alt_timestamp(); // 測量時間戳t49
Delay2(100000);
t50 = alt_timestamp(); // 測量時間戳t50
freq=alt_timestamp_freq();
printf("系統時鐘頻率是 %ld Hz\n", freq); //freq可以寫成ALT_CPU_FREQ
printf("\n");
printf("usleep(1)= %ld us\n",(t1-t0)/(ALT_CPU_FREQ/1000000));
printf("usleep(4)= %ld us\n",(t2-t1)/(ALT_CPU_FREQ/1000000));
printf("usleep(7)= %ld us\n",(t3-t2)/(ALT_CPU_FREQ/1000000));
printf("usleep(10)= %ld us\n",(t4-t3)/(ALT_CPU_FREQ/1000000));
printf("usleep(40)= %ld us\n",(t5-t4)/(ALT_CPU_FREQ/1000000));
printf("usleep(70)= %ld us\n",(t6-t5)/(ALT_CPU_FREQ/1000000));
printf("usleep(100)= %ld us\n",(t7-t6)/(ALT_CPU_FREQ/1000000));
printf("usleep(400)= %ld us\n",(t8-t7)/(ALT_CPU_FREQ/1000000));
printf("usleep(700)= %ld us\n",(t9-t8)/(ALT_CPU_FREQ/1000000));
printf("usleep(1000)= %ld us\n",(t10-t9)/(ALT_CPU_FREQ/1000000));
printf("usleep(4000)= %ld us\n",(t11-t10)/(ALT_CPU_FREQ/1000000));
printf("usleep(7000)= %ld us\n",(t12-t11)/(ALT_CPU_FREQ/1000000));
printf("usleep(10000)= %ld us\n",(t13-t12)/(ALT_CPU_FREQ/1000000));
printf("usleep(40000)= %ld us\n",(t14-t13)/(ALT_CPU_FREQ/1000000));
printf("usleep(70000)= %ld us\n",(t15-t14)/(ALT_CPU_FREQ/1000000));
printf("usleep(100000)= %ld us\n",(t16-t15)/(ALT_CPU_FREQ/1000000));
printf("\n");
printf("for(1)= %ld us\n",(t18-t17)/(ALT_CPU_FREQ/1000000));
printf("for(4)= %ld us\n",(t19-t18)/(ALT_CPU_FREQ/1000000));
printf("for(7)= %ld us\n",(t20-t19)/(ALT_CPU_FREQ/1000000));
printf("for(10)= %ld us\n",(t21-t20)/(ALT_CPU_FREQ/1000000));
printf("for(40)= %ld us\n",(t22-t21)/(ALT_CPU_FREQ/1000000));
printf("for(70)= %ld us\n",(t23-t22)/(ALT_CPU_FREQ/1000000));
printf("for(100)= %ld us\n",(t24-t23)/(ALT_CPU_FREQ/1000000));
printf("for(400)= %ld us\n",(t25-t24)/(ALT_CPU_FREQ/1000000));
printf("for(700)= %ld us\n",(t26-t25)/(ALT_CPU_FREQ/1000000));
printf("for(1000)= %ld us\n",(t27-t6)/(ALT_CPU_FREQ/1000000));
printf("for(4000)= %ld us\n",(t27-t27)/(ALT_CPU_FREQ/1000000));
printf("for(7000)= %ld us\n",(t29-t28)/(ALT_CPU_FREQ/1000000));
printf("for(10000)= %ld us\n",(t30-t29)/(ALT_CPU_FREQ/1000000));
printf("for(40000)= %ld us\n",(t31-t30)/(ALT_CPU_FREQ/1000000));
printf("for(70000)= %ld us\n",(t32-t31)/(ALT_CPU_FREQ/1000000));
printf("for(100000)= %ld us\n",(t33-t32)/(ALT_CPU_FREQ/1000000));
printf("\n");
printf("while(1)= %ld us\n",(t35-t34)/(ALT_CPU_FREQ/1000000));
printf("while(4)= %ld us\n",(t36-t35)/(ALT_CPU_FREQ/1000000));
printf("while(7)= %ld us\n",(t37-t36)/(ALT_CPU_FREQ/1000000));
printf("while(10)= %ld us\n",(t38-t37)/(ALT_CPU_FREQ/1000000));
printf("while(40)= %ld us\n",(t39-t38)/(ALT_CPU_FREQ/1000000));
printf("while(70)= %ld us\n",(t40-t39)/(ALT_CPU_FREQ/1000000));
printf("while(100)= %ld us\n",(t41-t40)/(ALT_CPU_FREQ/1000000));
printf("while(400)= %ld us\n",(t42-t41)/(ALT_CPU_FREQ/1000000));
printf("while(700)= %ld us\n",(t43-t42)/(ALT_CPU_FREQ/1000000));
printf("while(1000)= %ld us\n",(t44-t43)/(ALT_CPU_FREQ/1000000));
printf("while(4000)= %ld us\n",(t45-t44)/(ALT_CPU_FREQ/1000000));
printf("while(7000)= %ld us\n",(t46-t45)/(ALT_CPU_FREQ/1000000));
printf("while(10000)= %ld us\n",(t47-t46)/(ALT_CPU_FREQ/1000000));
printf("while(40000)= %ld us\n",(t48-t47)/(ALT_CPU_FREQ/1000000));
printf("while(70000)= %ld us\n",(t49-t48)/(ALT_CPU_FREQ/1000000));
printf("while(100000)= %ld us\n",(t50-t49)/(ALT_CPU_FREQ/1000000));
}
return 0;
}
{
printf("No timestamp device available\n");
}
else
{
//usleep
t0 = alt_timestamp(); // 測量時間戳t0
Delay0(1);
t1 = alt_timestamp(); // 測量時間戳t1
Delay0(4);
t2 = alt_timestamp(); // 測量時間戳t2
Delay0(7);
t3 = alt_timestamp(); // 測量時間戳t3
Delay0(10);
t4 = alt_timestamp(); // 測量時間戳t4
Delay0(40);
t5 = alt_timestamp(); // 測量時間戳t5
Delay0(70);
t6 = alt_timestamp(); // 測量時間戳t6
Delay0(100);
t7 = alt_timestamp(); // 測量時間戳t7
Delay0(400);
t8 = alt_timestamp(); // 測量時間戳t8
Delay0(700);
t9 = alt_timestamp(); // 測量時間戳t9
Delay0(1000);
t10 = alt_timestamp(); // 測量時間戳t10
Delay0(4000);
t11 = alt_timestamp(); // 測量時間戳t11
Delay0(7000);
t12 = alt_timestamp(); // 測量時間戳t12
Delay0(10000);
t13 = alt_timestamp(); // 測量時間戳t13
Delay0(40000);
t14 = alt_timestamp(); // 測量時間戳t14
Delay0(70000);
t15 = alt_timestamp(); // 測量時間戳t15
Delay0(100000);
t16 = alt_timestamp(); // 測量時間戳t16
//for
t17 = alt_timestamp(); // 測量時間戳t17
Delay1(1);
t18 = alt_timestamp(); // 測量時間戳t18
Delay1(4);
t19 = alt_timestamp(); // 測量時間戳t19
Delay1(7);
t20 = alt_timestamp(); // 測量時間戳t20
Delay1(10);
t21 = alt_timestamp(); // 測量時間戳t21
Delay1(40);
t22 = alt_timestamp(); // 測量時間戳t22
Delay1(70);
t23 = alt_timestamp(); // 測量時間戳t23
Delay1(100);
t24 = alt_timestamp(); // 測量時間戳t24
Delay1(400);
t25 = alt_timestamp(); // 測量時間戳t25
Delay1(700);
t26 = alt_timestamp(); // 測量時間戳t26
Delay1(1000);
t27 = alt_timestamp(); // 測量時間戳t27
Delay1(4000);
t28 = alt_timestamp(); // 測量時間戳t28
Delay1(7000);
t29 = alt_timestamp(); // 測量時間戳t29
Delay1(10000);
t30 = alt_timestamp(); // 測量時間戳t30
Delay1(40000);
t31 = alt_timestamp(); // 測量時間戳t31
Delay1(70000);
t32 = alt_timestamp(); // 測量時間戳t32
Delay1(100000);
t33 = alt_timestamp(); // 測量時間戳t33
//while
t34 = alt_timestamp(); // 測量時間戳t34
Delay2(1);
t35 = alt_timestamp(); // 測量時間戳t35
Delay2(4);
t36 = alt_timestamp(); // 測量時間戳t36
Delay2(7);
t37 = alt_timestamp(); // 測量時間戳t37
Delay2(10);
t38 = alt_timestamp(); // 測量時間戳t38
Delay2(40);
t39 = alt_timestamp(); // 測量時間戳t39
Delay2(70);
t40 = alt_timestamp(); // 測量時間戳t40
Delay2(100);
t41 = alt_timestamp(); // 測量時間戳t41
Delay2(400);
t42 = alt_timestamp(); // 測量時間戳t42
Delay2(700);
t43 = alt_timestamp(); // 測量時間戳t43
Delay2(1000);
t44 = alt_timestamp(); // 測量時間戳t44
Delay2(4000);
t45 = alt_timestamp(); // 測量時間戳t45
Delay2(7000);
t46 = alt_timestamp(); // 測量時間戳t46
Delay2(10000);
t47 = alt_timestamp(); // 測量時間戳t47
Delay2(40000);
t48 = alt_timestamp(); // 測量時間戳t48
Delay2(70000);
t49 = alt_timestamp(); // 測量時間戳t49
Delay2(100000);
t50 = alt_timestamp(); // 測量時間戳t50
freq=alt_timestamp_freq();
printf("系統時鐘頻率是 %ld Hz\n", freq); //freq可以寫成ALT_CPU_FREQ
printf("\n");
printf("usleep(1)= %ld us\n",(t1-t0)/(ALT_CPU_FREQ/1000000));
printf("usleep(4)= %ld us\n",(t2-t1)/(ALT_CPU_FREQ/1000000));
printf("usleep(7)= %ld us\n",(t3-t2)/(ALT_CPU_FREQ/1000000));
printf("usleep(10)= %ld us\n",(t4-t3)/(ALT_CPU_FREQ/1000000));
printf("usleep(40)= %ld us\n",(t5-t4)/(ALT_CPU_FREQ/1000000));
printf("usleep(70)= %ld us\n",(t6-t5)/(ALT_CPU_FREQ/1000000));
printf("usleep(100)= %ld us\n",(t7-t6)/(ALT_CPU_FREQ/1000000));
printf("usleep(400)= %ld us\n",(t8-t7)/(ALT_CPU_FREQ/1000000));
printf("usleep(700)= %ld us\n",(t9-t8)/(ALT_CPU_FREQ/1000000));
printf("usleep(1000)= %ld us\n",(t10-t9)/(ALT_CPU_FREQ/1000000));
printf("usleep(4000)= %ld us\n",(t11-t10)/(ALT_CPU_FREQ/1000000));
printf("usleep(7000)= %ld us\n",(t12-t11)/(ALT_CPU_FREQ/1000000));
printf("usleep(10000)= %ld us\n",(t13-t12)/(ALT_CPU_FREQ/1000000));
printf("usleep(40000)= %ld us\n",(t14-t13)/(ALT_CPU_FREQ/1000000));
printf("usleep(70000)= %ld us\n",(t15-t14)/(ALT_CPU_FREQ/1000000));
printf("usleep(100000)= %ld us\n",(t16-t15)/(ALT_CPU_FREQ/1000000));
printf("\n");
printf("for(1)= %ld us\n",(t18-t17)/(ALT_CPU_FREQ/1000000));
printf("for(4)= %ld us\n",(t19-t18)/(ALT_CPU_FREQ/1000000));
printf("for(7)= %ld us\n",(t20-t19)/(ALT_CPU_FREQ/1000000));
printf("for(10)= %ld us\n",(t21-t20)/(ALT_CPU_FREQ/1000000));
printf("for(40)= %ld us\n",(t22-t21)/(ALT_CPU_FREQ/1000000));
printf("for(70)= %ld us\n",(t23-t22)/(ALT_CPU_FREQ/1000000));
printf("for(100)= %ld us\n",(t24-t23)/(ALT_CPU_FREQ/1000000));
printf("for(400)= %ld us\n",(t25-t24)/(ALT_CPU_FREQ/1000000));
printf("for(700)= %ld us\n",(t26-t25)/(ALT_CPU_FREQ/1000000));
printf("for(1000)= %ld us\n",(t27-t6)/(ALT_CPU_FREQ/1000000));
printf("for(4000)= %ld us\n",(t27-t27)/(ALT_CPU_FREQ/1000000));
printf("for(7000)= %ld us\n",(t29-t28)/(ALT_CPU_FREQ/1000000));
printf("for(10000)= %ld us\n",(t30-t29)/(ALT_CPU_FREQ/1000000));
printf("for(40000)= %ld us\n",(t31-t30)/(ALT_CPU_FREQ/1000000));
printf("for(70000)= %ld us\n",(t32-t31)/(ALT_CPU_FREQ/1000000));
printf("for(100000)= %ld us\n",(t33-t32)/(ALT_CPU_FREQ/1000000));
printf("\n");
printf("while(1)= %ld us\n",(t35-t34)/(ALT_CPU_FREQ/1000000));
printf("while(4)= %ld us\n",(t36-t35)/(ALT_CPU_FREQ/1000000));
printf("while(7)= %ld us\n",(t37-t36)/(ALT_CPU_FREQ/1000000));
printf("while(10)= %ld us\n",(t38-t37)/(ALT_CPU_FREQ/1000000));
printf("while(40)= %ld us\n",(t39-t38)/(ALT_CPU_FREQ/1000000));
printf("while(70)= %ld us\n",(t40-t39)/(ALT_CPU_FREQ/1000000));
printf("while(100)= %ld us\n",(t41-t40)/(ALT_CPU_FREQ/1000000));
printf("while(400)= %ld us\n",(t42-t41)/(ALT_CPU_FREQ/1000000));
printf("while(700)= %ld us\n",(t43-t42)/(ALT_CPU_FREQ/1000000));
printf("while(1000)= %ld us\n",(t44-t43)/(ALT_CPU_FREQ/1000000));
printf("while(4000)= %ld us\n",(t45-t44)/(ALT_CPU_FREQ/1000000));
printf("while(7000)= %ld us\n",(t46-t45)/(ALT_CPU_FREQ/1000000));
printf("while(10000)= %ld us\n",(t47-t46)/(ALT_CPU_FREQ/1000000));
printf("while(40000)= %ld us\n",(t48-t47)/(ALT_CPU_FREQ/1000000));
printf("while(70000)= %ld us\n",(t49-t48)/(ALT_CPU_FREQ/1000000));
printf("while(100000)= %ld us\n",(t50-t49)/(ALT_CPU_FREQ/1000000));
}
return 0;
}
運行結果如下：
系統時鐘頻率是 50000000 Hz
usleep(1)= 42 us
usleep(4)= 38 us
usleep(7)= 40 us
usleep(10)= 44 us
usleep(40)= 72 us
usleep(70)= 102 us
usleep(100)= 130 us
usleep(400)= 418 us
usleep(700)= 706 us
usleep(1000)= 994 us
usleep(4000)= 3874 us
usleep(7000)= 6754 us
usleep(10000)= 9634 us
usleep(40000)= 38435 us
usleep(70000)= 67234 us
usleep(100000)= 96035 us
for(1)= 9 us
for(4)= 11 us
for(7)= 15 us
for(10)= 18 us
for(40)= 53 us
for(70)= 87 us
for(100)= 122 us
for(400)= 465 us
for(700)= 809 us
for(1000)= 226971 us
for(4000)= 0 us
for(7000)= 8018 us
for(10000)= 11452 us
for(40000)= 45782 us
for(70000)= 80115 us
for(100000)= 114447 us
while(1)= 7 us
while(4)= 10 us
while(7)= 11 us
while(10)= 14 us
while(40)= 35 us
while(70)= 58 us
while(100)= 79 us
while(400)= 298 us
while(700)= 516 us
while(1000)= 734 us
while(4000)= 2916 us
while(7000)= 5099 us
while(10000)= 7281 us
while(40000)= 29104 us
while(70000)= 50927 us
while(100000)= 72751 us
在ALT_CPU_FREQ處右擊，選中Open Declaration,可以找到ALT_CPU_FREQ在system.h中的定義。其值與函數alt_timestamp_freq()返回的值相同，都是在SOPC中設置的。如圖5所示。
圖5 系統時鐘設置
分析得知， 100us以下用while較準確， 100us以上用usleep。
補充：
1、 要在SOPC中加入Interval Timer，並在Nios II中”system library properties”中的”system library”中，爲timestamp timer指定物理設備，即在SOPCBuilder中添加的timer。否則出現如下錯誤。
2、 如果沒有頭文件alt_types.h，會出現如下警告。
3、（2011.5.31）
在調試好延時函數之後，要將紅圈處System Library Properties-> system library->Timestamp timer設置成none。本人就是遇到問題，比如最簡單的LED跑馬燈，同樣的ptf和Nios II程序，之前做的可以運行。設置timer之後，實驗沒有現象，也沒有提示錯誤，過了很久才找到的問題產生的原因。
4、（2011.6.15）對於時序比較複雜要求嚴格的控制，比如DS18B20，不適用於Nios II完全控制它的操作。先用硬件邏輯實現，再用Nios II讀取溫度數據的辦法較好。
4、（2011.6.15）對於時序比較複雜要求嚴格的控制，比如DS18B20，不適用於Nios II完全控制它的操作。先用硬件邏輯實現，再用Nios II讀取溫度數據的辦法較好。