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annotate py/touch/touch.c @ 536:3a27b1a09d2e
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| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Tue, 19 May 2015 23:58:51 +0800 |
| parents | e12d6d677320 |
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| rev | line source |
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| 454 | 1 // |
| 2 // How to access GPIO registers from C-code on the Raspberry-Pi | |
| 3 // Example program | |
| 4 // 15-January-2012 | |
| 5 // Dom and Gert | |
| 6 // | |
| 7 | |
| 8 | |
| 9 // Access from ARM Running Linux | |
| 10 | |
| 11 #define BCM2708_PERI_BASE 0x20000000 | |
| 12 #define GPIO_BASE (BCM2708_PERI_BASE + 0x200000) /* GPIO controller */ | |
| 13 | |
| 14 | |
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15 // for usleep |
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16 #define _BSD_SOURCE |
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17 |
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18 // clock_gettime |
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19 #define _POSIX_C_SOURCE 199309L |
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20 |
| 454 | 21 #include <stdio.h> |
| 22 #include <string.h> | |
| 23 #include <stdlib.h> | |
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24 #include <stdint.h> |
| 454 | 25 #include <dirent.h> |
| 26 #include <fcntl.h> | |
| 27 #include <assert.h> | |
| 28 #include <sys/mman.h> | |
| 29 #include <sys/types.h> | |
| 30 #include <sys/stat.h> | |
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31 #include <time.h> |
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32 #include <sched.h> |
| 454 | 33 |
| 34 #include <unistd.h> | |
| 35 | |
| 36 #define PAGE_SIZE (4*1024) | |
| 37 #define BLOCK_SIZE (4*1024) | |
| 38 | |
| 39 int mem_fd; | |
| 40 char *gpio_mem, *gpio_map; | |
| 41 char *spi0_mem, *spi0_map; | |
| 42 | |
| 43 | |
| 44 // I/O access | |
| 45 volatile unsigned *gpio; | |
| 46 | |
| 47 | |
| 48 // GPIO setup macros. Always use INP_GPIO(x) before using OUT_GPIO(x) or SET_GPIO_ALT(x,y) | |
| 49 #define INP_GPIO(g) *(gpio+((g)/10)) &= ~(7<<(((g)%10)*3)) | |
| 50 #define OUT_GPIO(g) *(gpio+((g)/10)) |= (1<<(((g)%10)*3)) | |
| 51 #define SET_GPIO_ALT(g,a) *(gpio+(((g)/10))) |= (((a)<=3?(a)+4:(a)==4?3:2)<<(((g)%10)*3)) | |
| 52 | |
| 53 #define FSEL_OFFSET 0 // 0x0000 | |
| 54 #define SET_OFFSET 7 // 0x001c / 4 | |
| 55 #define CLR_OFFSET 10 // 0x0028 / 4 | |
| 56 #define PINLEVEL_OFFSET 13 // 0x0034 / 4 | |
| 57 #define EVENT_DETECT_OFFSET 16 // 0x0040 / 4 | |
| 58 #define RISING_ED_OFFSET 19 // 0x004c / 4 | |
| 59 #define FALLING_ED_OFFSET 22 // 0x0058 / 4 | |
| 60 #define HIGH_DETECT_OFFSET 25 // 0x0064 / 4 | |
| 61 #define LOW_DETECT_OFFSET 28 // 0x0070 / 4 | |
| 62 #define PULLUPDN_OFFSET 37 // 0x0094 / 4 | |
| 63 #define PULLUPDNCLK_OFFSET 38 // 0x0098 / 4 | |
| 64 | |
| 65 | |
| 66 #define GPIO_GET(g) ((*(gpio+PINLEVEL_OFFSET) & (1<<(g))) >> (g)) | |
| 67 #define GPIO_SET(g) (*(gpio+SET_OFFSET) = 1<<(g)) // sets bits which are 1 ignores bits which are 0 | |
| 68 #define GPIO_CLR(g) (*(gpio+CLR_OFFSET) = 1<<(g))// clears bits which are 1 ignores bits which are 0 | |
| 69 | |
| 70 #define TOUCH_IN 24 | |
| 71 #define TOUCH_OUT 25 | |
| 72 | |
| 73 void setup_io(); | |
| 74 | |
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75 static int cmp_int(const void *a, const void *b) |
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76 { |
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77 const int *ia = a; |
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78 const int *ib = b; |
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79 return (*ia - *ib); |
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80 } |
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81 |
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82 static int clock_diff(struct timespec *t1, struct timespec *t2) |
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83 { |
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84 uint64_t v1 = t1->tv_sec * 1000000000 + t1->tv_nsec; |
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85 uint64_t v2 = t2->tv_sec * 1000000000 + t2->tv_nsec; |
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86 return v2-v1; |
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87 } |
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88 |
| 454 | 89 int main(int argc, char **argv) |
| 90 { | |
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91 // Set up gpi pointer for direct register access |
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92 setup_io(); |
| 454 | 93 |
| 94 INP_GPIO(TOUCH_IN); | |
| 95 INP_GPIO(TOUCH_OUT); | |
| 96 OUT_GPIO(TOUCH_OUT); | |
| 97 | |
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98 const int num = 200; |
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99 const int margin = 30; |
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100 int print = 0; |
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101 if (argc > 1) |
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102 { |
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103 print = 1; |
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104 } |
| 454 | 105 |
| 106 while (1) | |
| 107 { | |
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108 int vals[num]; |
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109 int nsecs[num]; |
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110 for (int n = 0; n < num; n++) |
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111 { |
| 454 | 112 GPIO_CLR(TOUCH_OUT); |
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113 struct timespec t = {.tv_nsec=20}; |
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114 nanosleep(&t, NULL); |
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115 //sched_yield(); |
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116 //usleep(1); |
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117 if (GPIO_GET(TOUCH_IN)) |
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118 { |
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119 printf("short "); |
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120 } |
| 454 | 121 GPIO_SET(TOUCH_OUT); |
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122 int val = 0; |
| 454 | 123 while (GPIO_GET(TOUCH_IN) == 0) |
| 124 { | |
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125 val++; |
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126 } |
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127 |
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128 vals[n] = val; |
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129 } |
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130 qsort(vals, num, sizeof(*vals), cmp_int); |
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131 int sum = 0, count = 0; |
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132 for (int n = 0; n < num; n++) |
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133 { |
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134 if (print) |
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135 { |
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136 printf("%3d ", vals[n]); |
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137 if (n == num-1 || n % 10 == 9) |
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138 { |
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139 printf("\n"); |
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140 } |
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141 if (n == margin || n == num-margin) |
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142 { |
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143 printf("#"); |
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144 } |
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145 } |
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146 if (n >= margin && n < (num-margin)) |
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147 { |
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148 sum += vals[n]; |
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149 count ++; |
| 454 | 150 } |
| 151 } | |
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152 printf("total %f from %d\n", (float)sum / count, count); |
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153 usleep(500000); |
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154 } |
| 454 | 155 return 0; |
| 156 | |
| 157 } // main | |
| 158 | |
| 159 | |
| 160 // | |
| 161 // Set up a memory regions to access GPIO | |
| 162 // | |
| 163 void setup_io() | |
| 164 { | |
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165 /* open /dev/mem */ |
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166 if ((mem_fd = open("/dev/mem", O_RDWR|O_SYNC) ) < 0) { |
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167 printf("can't open /dev/mem \n"); |
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168 exit (-1); |
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169 } |
| 454 | 170 |
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171 /* mmap GPIO */ |
| 454 | 172 |
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173 // Allocate MAP block |
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174 if ((gpio_mem = malloc(BLOCK_SIZE + (PAGE_SIZE-1))) == NULL) { |
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175 printf("allocation error \n"); |
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176 exit (-1); |
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177 } |
| 454 | 178 |
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179 // Make sure pointer is on 4K boundary |
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180 if ((unsigned long)gpio_mem % PAGE_SIZE) |
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181 gpio_mem += PAGE_SIZE - ((unsigned long)gpio_mem % PAGE_SIZE); |
| 454 | 182 |
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183 // Now map it |
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184 gpio_map = mmap( |
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185 (caddr_t)gpio_mem, |
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186 BLOCK_SIZE, |
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187 PROT_READ|PROT_WRITE, |
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188 MAP_SHARED|MAP_FIXED, |
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189 mem_fd, |
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190 GPIO_BASE |
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191 ); |
| 454 | 192 |
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193 if ((long)gpio_map < 0) { |
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194 printf("mmap error %d\n", (int)gpio_map); |
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195 exit (-1); |
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196 } |
| 454 | 197 |
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198 // Always use volatile pointer! |
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199 gpio = (volatile unsigned *)gpio_map; |
| 454 | 200 |
| 201 | |
| 202 } // setup_io |