This program calculate location of Wi-Fi receiver, by using AP beacon. Please check the Japanese magazine "Interface 2012/12".
LocationHandler.h
- Committer:
- nakata
- Date:
- 2012-09-10
- Revision:
- 1:2f2f793fcf4f
- Parent:
- 0:4eaf38ccb19c
File content as of revision 1:2f2f793fcf4f:
#include <math.h> #include <string.h> #define NOTFOUND_MARK (-65536) struct apinfo registered_ap[] = { { "ap-game-432afd", {0, 0x22, 0xcf, 0x43, 0x2a, 0xfd}, 0 }, { "ap-pc-432afc", {0, 0x22, 0xcf, 0x43, 0x2a, 0xfc}, 0 }, { "ap-game-433f85", {0, 0x22, 0xcf, 0x43, 0x3f, 0x85}, 0 }, { "ap-pc-433f84", {0, 0x22, 0xcf, 0x43, 0x3f, 0x84}, 0 }, { "ap-game-433223", {0, 0x22, 0xcf, 0x43, 0x32, 0x23}, 0 }, { "ap-pc-433222", {0, 0x22, 0xcf, 0x43, 0x32, 0x22}, 0 }, { "ap-game-4334c9", {0, 0x22, 0xcf, 0x43, 0x34, 0xc9}, 0 }, { "ap-pc-4334c8", {0, 0x22, 0xcf, 0x43, 0x34, 0xc8}, 0 } }; // this structure must be writable struct pos { float x, y; }; const struct pos registered_pos[] = { {0.0, 0.0}, {0.0, 0.0}, {0.0, 100.0}, {0.0, 100.0}, {100.0, 0.0}, {100.0, 0.0}, {100.0, 100.0}, {100.0, 100.0} }; struct pos result_pos; void LocationManagerCalcPos(int apinfo_count, struct apinfo* searched_ap) { int i, j, k; int match_count; const int length_of_registered_ap = sizeof(registered_ap) / sizeof(struct apinfo); float proportion; float sum; for ( i = 0; i < length_of_registered_ap; i++ ) { registered_ap[i].power = NOTFOUND_MARK; } match_count = 0; for ( i = 0; i < apinfo_count; i++ ) { for ( j = 0; j < length_of_registered_ap; j++ ) { for ( k = 0; k < ESSID_LEN; k++ ) { if ( registered_ap[j].essid[k] == '\0' ) { break; } if ( searched_ap[i].essid[k] != registered_ap[j].essid[k] ) { goto no_match; } } if ( memcmp( registered_ap[j].bssid, searched_ap[i].bssid, MACADDR_LEN) != 0 ) { continue; } registered_ap[j].power = searched_ap[i].power; match_count++; break; no_match:; } } if ( match_count == 0 ) { lcd.cls(); lcd.printf("location lost\nAP count %d", apinfo_count); return; } result_pos.x = result_pos.y = 0.0; sum = 0.0; for ( i = 0; i < length_of_registered_ap; i++ ) { proportion = pow(10, registered_ap[i].power / 40.0f); // calc dB to linear number sum += proportion; result_pos.x += registered_pos[i].x * proportion; result_pos.y += registered_pos[i].y * proportion; } result_pos.x /= sum; result_pos.y /= sum; lcd.cls(); lcd.printf("AP %d/%d, location x=%.1f, y=%.1f", match_count, apinfo_count, result_pos.x, result_pos.y); }