Craig Evans / Mbed 2 deprecated 2545_SD_Card

Example of using the SDFileSystem library on a K64F to write data to files and also read data into dynamically created arrays.

Dependencies:   mbed

main.cpp@1:caceb9d9d17a, 2020-02-03 (annotated)

Committer:
eencae
Date:
Mon Feb 03 12:06:21 2020 +0000
Revision:
1:caceb9d9d17a
Parent:
0:5448330e1a33 
Updated Mbed library. Removed serial. Confirmed working Jan 2020.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
eencae 0:5448330e1a33 1 /* 2545_SD_Card Example
eencae 0:5448330e1a33 2
eencae 0:5448330e1a33 3 Example of writing data to SD card.
eencae 0:5448330e1a33 4
eencae 0:5448330e1a33 5 Based on FTF2014_lab4 Example
eencae 0:5448330e1a33 6
eencae 0:5448330e1a33 7 https://developer.mbed.org/teams/Freescale/wiki/FTF2014_workshop
eencae 0:5448330e1a33 8
eencae 0:5448330e1a33 9 Craig A. Evans, University of Leeds, Mar 2016
eencae 0:5448330e1a33 10
eencae 0:5448330e1a33 11 */
eencae 0:5448330e1a33 12
eencae 0:5448330e1a33 13 #include "mbed.h"
eencae 0:5448330e1a33 14 #include "SDFileSystem.h"
eencae 0:5448330e1a33 15
eencae 0:5448330e1a33 16 // Connections to SD card holder on K64F (SPI interface)
eencae 0:5448330e1a33 17 SDFileSystem sd(PTE3, PTE1, PTE2, PTE4, "sd"); // MOSI, MISO, SCK, CS
eencae 0:5448330e1a33 18
eencae 0:5448330e1a33 19 void delete_file(char filename[]);
eencae 0:5448330e1a33 20
eencae 0:5448330e1a33 21 int main()
eencae 0:5448330e1a33 22 {
eencae 1:caceb9d9d17a 23 printf("#### SD Card Example #####\n");
eencae 0:5448330e1a33 24 FILE *fp; // this is our file pointer
eencae 0:5448330e1a33 25 wait(1);
eencae 0:5448330e1a33 26
eencae 0:5448330e1a33 27 // Various examples below - can comment out ones you don't need
eencae 0:5448330e1a33 28
eencae 0:5448330e1a33 29 /////////////////////// Deleting file example ////////////////////////
eencae 0:5448330e1a33 30
eencae 0:5448330e1a33 31 // comment this line out if you don't want to delete the file!
eencae 0:5448330e1a33 32 delete_file("/sd/test.txt");
eencae 0:5448330e1a33 33
eencae 0:5448330e1a33 34 ////////////////////// Simple writing example //////////////////////////
eencae 0:5448330e1a33 35
eencae 0:5448330e1a33 36 // open file for writing ('w') - creates file if it doesn't exist and overwrites
eencae 0:5448330e1a33 37 // if it does. If you wish to add a score onto a list, then you can
eencae 0:5448330e1a33 38 // append instead 'a'. This will open the file if it exists and start
eencae 0:5448330e1a33 39 // writing at the end. It will create the file if it doesn't exist.
eencae 0:5448330e1a33 40 fp = fopen("/sd/topscore.txt", "w");
eencae 0:5448330e1a33 41 int top_score = 56; // random example
eencae 0:5448330e1a33 42
eencae 0:5448330e1a33 43 if (fp == NULL) { // if it can't open the file then print error message
eencae 1:caceb9d9d17a 44 printf("Error! Unable to open file!\n");
eencae 0:5448330e1a33 45 } else { // opened file so can write
eencae 1:caceb9d9d17a 46 printf("Writing to file....");
eencae 0:5448330e1a33 47 fprintf(fp, "%d",top_score); // ensure data type matches
eencae 1:caceb9d9d17a 48 printf("Done.\n");
eencae 0:5448330e1a33 49 fclose(fp); // ensure you close the file after writing
eencae 0:5448330e1a33 50 }
eencae 0:5448330e1a33 51
eencae 0:5448330e1a33 52 ////////////////////// Simple reading example //////////////////////////
eencae 0:5448330e1a33 53
eencae 0:5448330e1a33 54 // now open file for reading
eencae 0:5448330e1a33 55 fp = fopen("/sd/topscore.txt", "r");
eencae 0:5448330e1a33 56 int stored_top_score = -1; // -1 to demonstrate it has changed after reading
eencae 0:5448330e1a33 57
eencae 0:5448330e1a33 58 if (fp == NULL) { // if it can't open the file then print error message
eencae 1:caceb9d9d17a 59 printf("Error! Unable to open file!\n");
eencae 0:5448330e1a33 60 } else { // opened file so can write
eencae 0:5448330e1a33 61 fscanf(fp, "%d",&stored_top_score); // ensure data type matches - note address operator (&)
eencae 1:caceb9d9d17a 62 printf("Read %d from file.\n",stored_top_score);
eencae 0:5448330e1a33 63 fclose(fp); // ensure you close the file after reading
eencae 0:5448330e1a33 64 }
eencae 0:5448330e1a33 65
eencae 0:5448330e1a33 66 ///////////////////// Writing list to file example //////////////////////
eencae 0:5448330e1a33 67
eencae 0:5448330e1a33 68 // for this example, I'll create some numbers to write to file in a big list
eencae 0:5448330e1a33 69 // a data logger for example will usually append to a file - at a reading
eencae 0:5448330e1a33 70 // at the end rather than creating a new file
eencae 0:5448330e1a33 71 fp = fopen("/sd/test.txt", "a");
eencae 0:5448330e1a33 72
eencae 0:5448330e1a33 73 if (fp == NULL) { // if it can't open the file then print error message
eencae 1:caceb9d9d17a 74 printf("Error! Unable to open file!\n");
eencae 0:5448330e1a33 75 } else { // opened file so can write
eencae 1:caceb9d9d17a 76 printf("Writing to file....");
eencae 0:5448330e1a33 77 for(int i = 1; i <= 50; i++) {
eencae 0:5448330e1a33 78 float dummy = 1000.0F/i; // dummy variable
eencae 0:5448330e1a33 79 fprintf(fp, "%d,%f\n",i,dummy); // print formatted string to file (CSV)
eencae 0:5448330e1a33 80 }
eencae 1:caceb9d9d17a 81 printf("Done.\n");
eencae 0:5448330e1a33 82 fclose(fp); // ensure you close the file after writing
eencae 0:5448330e1a33 83 }
eencae 0:5448330e1a33 84
eencae 0:5448330e1a33 85 // you can comment out the writing example to check that the writing has
eencae 0:5448330e1a33 86 // worked - when you run it after commenting, it should still open the
eencae 0:5448330e1a33 87 // file that exists on the SD card - assuming you didn't delete it!
eencae 0:5448330e1a33 88
eencae 0:5448330e1a33 89 /////////////////////// Reading from file example ////////////////////////
eencae 0:5448330e1a33 90
eencae 0:5448330e1a33 91 // now open file for reading...note the 'r'
eencae 0:5448330e1a33 92 fp = fopen("/sd/test.txt", "r");
eencae 0:5448330e1a33 93 if (fp == NULL) { // if it can't open the file then print error message
eencae 1:caceb9d9d17a 94 printf("Error! Unable to open file!\n");
eencae 0:5448330e1a33 95 } else {
eencae 1:caceb9d9d17a 96 printf("Reading file....\n");
eencae 0:5448330e1a33 97 int i; // create suitable variables to store the data in the file
eencae 0:5448330e1a33 98 float value;
eencae 0:5448330e1a33 99
eencae 0:5448330e1a33 100 // in this example, we keep reading (using fscanf) until we reach
eencae 0:5448330e1a33 101 // the 'end of file'. Note we use the address operator & to write
eencae 0:5448330e1a33 102 // to the variables. Also the format of the string must match what
eencae 0:5448330e1a33 103 // is in the file
eencae 0:5448330e1a33 104 while (fscanf(fp, "%d,%f", &i, &value) != EOF) {
eencae 1:caceb9d9d17a 105 printf("%d,%f\n",i,value);
eencae 0:5448330e1a33 106 }
eencae 1:caceb9d9d17a 107 printf("Done.\n");
eencae 0:5448330e1a33 108 fclose(fp); // ensure you close the file after reading
eencae 0:5448330e1a33 109 }
eencae 0:5448330e1a33 110
eencae 0:5448330e1a33 111 ///////////////// Advanced Reading from file example ///////////////////
eencae 0:5448330e1a33 112
eencae 0:5448330e1a33 113 // the previous example just read the values into variables and printed to
eencae 0:5448330e1a33 114 // serial, we'll now read files into an array.
eencae 0:5448330e1a33 115
eencae 0:5448330e1a33 116 // now open file for reading...note the 'r'
eencae 0:5448330e1a33 117 fp = fopen("/sd/test.txt", "r");
eencae 0:5448330e1a33 118
eencae 0:5448330e1a33 119 int n=0; // going to store the number of lines in the file
eencae 0:5448330e1a33 120 int *index_array; // pointers to create dynamic arrays later
eencae 0:5448330e1a33 121 float *value_array; // note memory will be in heap rather than on the stack
eencae 0:5448330e1a33 122
eencae 0:5448330e1a33 123 if (fp == NULL) { // if it can't open the file then print error message
eencae 1:caceb9d9d17a 124 printf("Error! Unable to open file!\n");
eencae 0:5448330e1a33 125 } else {
eencae 1:caceb9d9d17a 126 printf("Counting lines in file....\n");
eencae 0:5448330e1a33 127 //Since we may not know the
eencae 0:5448330e1a33 128 // number of lines in the files ahead of time, we'll first count them
eencae 0:5448330e1a33 129 // * means scan but don't save
eencae 0:5448330e1a33 130 while (fscanf(fp, "%*d,%*f") != EOF) {
eencae 0:5448330e1a33 131 n++; // increment counter when read a line
eencae 0:5448330e1a33 132 }
eencae 0:5448330e1a33 133
eencae 0:5448330e1a33 134
eencae 1:caceb9d9d17a 135 printf("Read %d lines\n",n);
eencae 1:caceb9d9d17a 136 printf("Creating dynamic arrays...\n");
eencae 0:5448330e1a33 137 // calloc creates an array and initilises to 0
eencae 0:5448330e1a33 138 // malloc returns unitialised array - diffrent syntax
eencae 0:5448330e1a33 139 index_array = (int *)calloc(n, sizeof (int));
eencae 0:5448330e1a33 140 value_array = (float *)calloc(n, sizeof (float));
eencae 0:5448330e1a33 141
eencae 0:5448330e1a33 142 int i=0;
eencae 0:5448330e1a33 143 rewind(fp); // 'scrolled' to end of file, so go back to beginning
eencae 1:caceb9d9d17a 144 printf("Reading into arrays...\n");
eencae 0:5448330e1a33 145 while (fscanf(fp, "%d,%f",&index_array[i],&value_array[i]) != EOF) {
eencae 0:5448330e1a33 146 i++; // read data into array and increment index
eencae 0:5448330e1a33 147 }
eencae 1:caceb9d9d17a 148 printf("Done.\n");
eencae 0:5448330e1a33 149 fclose(fp); // ensure you close the file after reading
eencae 0:5448330e1a33 150 }
eencae 0:5448330e1a33 151
eencae 0:5448330e1a33 152 // we should now have the data in the arrays, will print to serial to check
eencae 0:5448330e1a33 153 for(int i=0; i<n ; i++) {
eencae 1:caceb9d9d17a 154 printf("[%d] %d,%f\n",i,index_array[i],value_array[i]);
eencae 0:5448330e1a33 155 }
eencae 0:5448330e1a33 156
eencae 0:5448330e1a33 157 ///////////////////////////////////////////////////
eencae 1:caceb9d9d17a 158 printf("End of SD card example\n");
eencae 0:5448330e1a33 159 }
eencae 0:5448330e1a33 160
eencae 0:5448330e1a33 161 void delete_file(char filename[])
eencae 0:5448330e1a33 162 {
eencae 1:caceb9d9d17a 163 printf("Deleting file '%s'...",filename);
eencae 0:5448330e1a33 164 FILE *fp = fopen(filename, "r"); // try and open file
eencae 0:5448330e1a33 165 if (fp != NULL) { // if it does open...
eencae 0:5448330e1a33 166 fclose(fp); // close it
eencae 0:5448330e1a33 167 remove(filename); // and then delete
eencae 1:caceb9d9d17a 168 printf("Done!\n");
eencae 0:5448330e1a33 169 }
eencae 0:5448330e1a33 170 // if we can't open it, it doesn't exist and so we can't delete it
eencae 0:5448330e1a33 171 }