Hiroshi Nakata / Mbed 2 deprecated WiFiPositioning

This program calculate location of Wi-Fi receiver, by using AP beacon. Please check the Japanese magazine "Interface 2012/12".

Dependencies:   TextLCD mbed

LocationHandler.h@1:2f2f793fcf4f, 2012-09-10 (annotated)

Committer:
nakata
Date:
Mon Sep 10 07:15:35 2012 +0000
Revision:
1:2f2f793fcf4f
Parent:
0:4eaf38ccb19c 
for Interface

Who changed what in which revision?

UserRevisionLine numberNew contents of line
nakata 0:4eaf38ccb19c 1 #include <math.h>
nakata 0:4eaf38ccb19c 2 #include <string.h>
nakata 0:4eaf38ccb19c 3
nakata 0:4eaf38ccb19c 4 #define NOTFOUND_MARK (-65536)
nakata 0:4eaf38ccb19c 5
nakata 0:4eaf38ccb19c 6 struct apinfo registered_ap[] = {
nakata 0:4eaf38ccb19c 7 { "ap-game-432afd", {0, 0x22, 0xcf, 0x43, 0x2a, 0xfd}, 0 },
nakata 0:4eaf38ccb19c 8 { "ap-pc-432afc", {0, 0x22, 0xcf, 0x43, 0x2a, 0xfc}, 0 },
nakata 0:4eaf38ccb19c 9 { "ap-game-433f85", {0, 0x22, 0xcf, 0x43, 0x3f, 0x85}, 0 },
nakata 0:4eaf38ccb19c 10 { "ap-pc-433f84", {0, 0x22, 0xcf, 0x43, 0x3f, 0x84}, 0 },
nakata 0:4eaf38ccb19c 11 { "ap-game-433223", {0, 0x22, 0xcf, 0x43, 0x32, 0x23}, 0 },
nakata 0:4eaf38ccb19c 12 { "ap-pc-433222", {0, 0x22, 0xcf, 0x43, 0x32, 0x22}, 0 },
nakata 0:4eaf38ccb19c 13 { "ap-game-4334c9", {0, 0x22, 0xcf, 0x43, 0x34, 0xc9}, 0 },
nakata 0:4eaf38ccb19c 14 { "ap-pc-4334c8", {0, 0x22, 0xcf, 0x43, 0x34, 0xc8}, 0 }
nakata 0:4eaf38ccb19c 15 }; // this structure must be writable
nakata 0:4eaf38ccb19c 16
nakata 0:4eaf38ccb19c 17 struct pos {
nakata 0:4eaf38ccb19c 18 float x, y;
nakata 0:4eaf38ccb19c 19 };
nakata 0:4eaf38ccb19c 20
nakata 0:4eaf38ccb19c 21 const struct pos registered_pos[] = {
nakata 0:4eaf38ccb19c 22 {0.0, 0.0}, {0.0, 0.0}, {0.0, 100.0}, {0.0, 100.0},
nakata 0:4eaf38ccb19c 23 {100.0, 0.0}, {100.0, 0.0}, {100.0, 100.0}, {100.0, 100.0}
nakata 0:4eaf38ccb19c 24 };
nakata 0:4eaf38ccb19c 25
nakata 0:4eaf38ccb19c 26 struct pos result_pos;
nakata 0:4eaf38ccb19c 27
nakata 0:4eaf38ccb19c 28 void LocationManagerCalcPos(int apinfo_count, struct apinfo* searched_ap)
nakata 0:4eaf38ccb19c 29 {
nakata 0:4eaf38ccb19c 30 int i, j, k;
nakata 0:4eaf38ccb19c 31 int match_count;
nakata 0:4eaf38ccb19c 32 const int length_of_registered_ap = sizeof(registered_ap) / sizeof(struct apinfo);
nakata 0:4eaf38ccb19c 33 float proportion;
nakata 0:4eaf38ccb19c 34 float sum;
nakata 0:4eaf38ccb19c 35
nakata 0:4eaf38ccb19c 36 for ( i = 0; i < length_of_registered_ap; i++ ) {
nakata 0:4eaf38ccb19c 37 registered_ap[i].power = NOTFOUND_MARK;
nakata 0:4eaf38ccb19c 38 }
nakata 0:4eaf38ccb19c 39 match_count = 0;
nakata 0:4eaf38ccb19c 40 for ( i = 0; i < apinfo_count; i++ ) {
nakata 0:4eaf38ccb19c 41 for ( j = 0; j < length_of_registered_ap; j++ ) {
nakata 0:4eaf38ccb19c 42 for ( k = 0; k < ESSID_LEN; k++ ) {
nakata 0:4eaf38ccb19c 43 if ( registered_ap[j].essid[k] == '\0' ) {
nakata 0:4eaf38ccb19c 44 break;
nakata 0:4eaf38ccb19c 45 }
nakata 0:4eaf38ccb19c 46 if ( searched_ap[i].essid[k] != registered_ap[j].essid[k] ) {
nakata 0:4eaf38ccb19c 47 goto no_match;
nakata 0:4eaf38ccb19c 48 }
nakata 0:4eaf38ccb19c 49 }
nakata 0:4eaf38ccb19c 50 if ( memcmp( registered_ap[j].bssid, searched_ap[i].bssid, MACADDR_LEN) != 0 ) {
nakata 0:4eaf38ccb19c 51 continue;
nakata 0:4eaf38ccb19c 52 }
nakata 0:4eaf38ccb19c 53 registered_ap[j].power = searched_ap[i].power;
nakata 0:4eaf38ccb19c 54 match_count++;
nakata 0:4eaf38ccb19c 55 break;
nakata 0:4eaf38ccb19c 56 no_match:;
nakata 0:4eaf38ccb19c 57 }
nakata 0:4eaf38ccb19c 58 }
nakata 0:4eaf38ccb19c 59
nakata 0:4eaf38ccb19c 60 if ( match_count == 0 ) {
nakata 0:4eaf38ccb19c 61 lcd.cls();
nakata 0:4eaf38ccb19c 62 lcd.printf("location lost\nAP count %d", apinfo_count);
nakata 0:4eaf38ccb19c 63 return;
nakata 0:4eaf38ccb19c 64 }
nakata 0:4eaf38ccb19c 65
nakata 0:4eaf38ccb19c 66 result_pos.x = result_pos.y = 0.0;
nakata 0:4eaf38ccb19c 67 sum = 0.0;
nakata 0:4eaf38ccb19c 68 for ( i = 0; i < length_of_registered_ap; i++ ) {
nakata 0:4eaf38ccb19c 69 proportion = pow(10, registered_ap[i].power / 40.0f); // calc dB to linear number
nakata 0:4eaf38ccb19c 70 sum += proportion;
nakata 0:4eaf38ccb19c 71 result_pos.x += registered_pos[i].x * proportion;
nakata 0:4eaf38ccb19c 72 result_pos.y += registered_pos[i].y * proportion;
nakata 0:4eaf38ccb19c 73 }
nakata 0:4eaf38ccb19c 74 result_pos.x /= sum;
nakata 0:4eaf38ccb19c 75 result_pos.y /= sum;
nakata 0:4eaf38ccb19c 76
nakata 0:4eaf38ccb19c 77 lcd.cls();
nakata 0:4eaf38ccb19c 78 lcd.printf("AP %d/%d, location x=%.1f, y=%.1f", match_count, apinfo_count, result_pos.x, result_pos.y);
nakata 0:4eaf38ccb19c 79 }