2014年11月24日

   1: #include<stdio.h>   2: #include<stdlib.h>   3: #include<string.h>   4: #include<errno.h>   5: #include<unistd.h>   6: #include<sys/types.h>   7: #include<sys/socket.h>   8: #include<sys/time.h>   9: #include<linux/in.h>  10:    11: /*Used to set NTP protocol version*/  12: #define NTP_Version 0x4  13: /*Sets NTP mode to client*/  14: #define Mode_Client 0x3  15: /*NTP counts time from 1-1-1900, we must subtract 70 years to go to epoch*/  16: #define _1_1_1970_ 0x83AA7E80  17:    18: /*Message structure for NTP message according to rfc4330*/  19: typedef struct struct_sntp_msg{  20:   unsigned char LI : 2;  21:   unsigned char VN : 3;  22:   unsigned char Mode : 3;  23:   unsigned char Stratum;  24:   unsigned char Poll;  25:   unsigned char Precision;  26:   unsigned int root_delay;  27:   unsigned int root_dispersion;  28:   unsigned int ref_id;  29:   unsigned int ref_timestamp;  30:   unsigned int ref_timestamp_nanosecs;  31:   unsigned int orig_timestamp;  32:   unsigned int orig_timestamp_nanosecs;  33:   unsigned int rx_timestamp;  34:   unsigned int rx_timestamp_nanosecs;  35:   unsigned int tx_timestamp;  36:   unsigned int tx_timestamp_nanosecs;  37:   unsigned int key_identifier;  38:   unsigned char msg_digest[16];  39: } sntp_msg;  40:    41: /*Creates an NTP message, Using empty transmission time, since we will sync  42: with the time of the server, we dont a big precision therefore we will not use  43: the algorithms specified in RFC4330*/  44: int fillReqMessage (sntp_msg *outMsg){  45:   if(outMsg==NULL){  46:     return -1;  47:   }  48:   memset(outMsg, 0x0, sizeof(sntp_msg));  49:   outMsg->LI = 0x3; //clock not synchronized  50:   outMsg->VN = NTP_Version;  51:   outMsg->Mode = Mode_Client;  52:   return 0;  53: }  54:    55: /*Sets the system time based on the epoch value*/  56: int set_SystemTime(unsigned int epoch){  57:   struct timeval tv;  58:   struct timezone tz;  59:   memset(&tv, 0x0, sizeof(struct timeval));  60:   /*Timezone value is considered in the epoch time and we ignore DST*/  61:   memset(&tz, 0x0, sizeof(struct timezone));  62:   tv.tv_sec = epoch;  63:   if( settimeofday(&tv, &tz) == -1){  64:     fprintf(stderr,"Failed to gettimeofday %s \n",strerror(errno));  65:     return -1;  66:   }  67:   else  68:     return 0;  69: }  70:    71: int main (int argc, char* argv[]){  72:     73:   int offset = 0;  74:   //Parsing cmdLine  75:   if(argc != 2){  76:     fprintf(stdout,"\t/******************************************************/\n");  77:     fprintf(stdout,"\t/*                                                    */\n");  78:     fprintf(stdout,"\t/*                   USAGE                            */\n");  79:     fprintf(stdout,"\t/*                                                    */\n");  80:     fprintf(stdout,"\t/*      ./timesync TIMEZONEOFFSET                     */\n");  81:     fprintf(stdout,"\t/*                                                    */\n");  82:     fprintf(stdout,"\t/*    TIMEZONEOFFSET minutes to add/remove to GMT     */\n");  83:     fprintf(stdout,"\t/*                                                    */\n");  84:     fprintf(stdout,"\t/*                                                    */\n");  85:     fprintf(stdout,"\t/******************************************************/\n");  86:     return 0;  87:   }  88:   else{  89:     /*Saving offset in minutes*/  90:     offset = atoi(argv[1]);  91:   }  92:    93:    94:   sntp_msg outMsg;  95:   sntp_msg inMsg;  96:   int sock = 0;  97:   unsigned int epochTime = 0;  98:   struct sockaddr_in ntpaddr;  99:   memset(&ntpaddr, 0x0, sizeof(struct sockaddr_in)); 100:   ntpaddr.sin_family = AF_INET; 101:   /*Setting IP address of ntp server*/ 102:   inet_aton("95.130.9.63",&(ntpaddr.sin_addr.s_addr)); 103:   /*Setting port for NTP protocol*/ 104:   ntpaddr.sin_port = htons(123); 105:    106:   /*Create the message*/ 107:   if(fillReqMessage(&outMsg)){ 108:     fprintf(stderr,"Failed to create Message\n"); 109:     return -1; 110:   } 111:   /*Creating the socket*/ 112:   if( ( sock = socket(AF_INET, SOCK_DGRAM, 0 ) ) == -1){ 113:     fprintf(stderr,"Failed to  open socket %s \n",strerror(errno)); 114:     return -1; 115:   } 116:   /*Connecting the socket*/ 117:   if( connect( sock, (struct sockaddr*) &ntpaddr, sizeof(struct sockaddr) ) < 0 ){ 118:     fprintf(stderr,"Failed to connect socket %s \n",strerror(errno)); 119:     close(sock); 120:     return -1; 121:   } 122:   /*Sending*/ 123:   if( send( sock, (void*) &outMsg, sizeof(sntp_msg), 0 ) != sizeof(sntp_msg) ){ 124:     fprintf(stderr,"Failed to tx %s \n",strerror(errno)); 125:     close(sock); 126:     return -1; 127:   } 128:   /*Receiving from the socket, we will just wync our clock with the server time 129:   we dont anymore precision*/ 130:   if( recv( sock, (void*) &inMsg, sizeof(sntp_msg), 0 ) ==-1){ 131:     fprintf(stderr,"Failed to rx %s \n",strerror(errno)); 132:     close(sock); 133:     return -1; 134:   } 135:   /*Cleaning up*/ 136:   if( close(sock) == -1){ 137:     fprintf(stderr,"Failed to close socket %s \n",strerror(errno)); 138:     return -1; 139:   } 140:    141:   /*Reinterpreting received info*/ 142:   //fprintf(stdout,"Updated Time is: 0x%X %u\n",ntohl(inMsg.tx_timestamp),(unsigned int) ntohl(inMsg.tx_timestamp)); 143:   /*unix time measures time in seconds from 1-1-1970 whereas NTP measures time 144:   in seconds from 1-1-1900 (RFC4330), to convert we must remove 70 years in 145:   seconds and finally add the offset in seconds from GMT*/ 146:   epochTime = ntohl(inMsg.tx_timestamp) - _1_1_1970_ + (offset*60); 147:   148:   /*Updating System time and date*/ 149:   if( set_SystemTime(epochTime) == -1 ) 150:     return -1; 151:   152:    153:   fprintf(stdout,"Updated Time is: %u\n",epochTime); 154:   155:   return 0; 156: } 157:   158:  

三軸加速度計ADXL345

Analog

ADXL345

http://www.analog.com/en/ADXL345

2014年6月15日

note

http://forums.dearhoney.idv.tw/viewtopic.php?f=3&t=52072

2014年4月2日

UNIX timestamp 轉換本地時間

http://www.epochconverter.com/

2014年3月27日

& 0xFF的意思

只取後面8bit的意思

int 的長度是 4Bytes， & 是 and 運算子，就是將

每個位元拿來進行 and 運算，根據 and 運算的規則

只有兩者皆為 true (1) 的結果才為 1

假設這個 i 是 12345 => 0x3039 (Hex)

i & 0xFF

0x3039=>0011000000111001(Bin)

0xFF　=>0000000011111111

____________________________

結果： 0000000000111001

由於前面的 bits 都是 0 ，所以實際上有用的只有後面的 8 bits

Reference:

http://acm.nudt.edu.cn/~twcourse/BitwiseOperation.html

http://programming.im.ncnu.edu.tw/Chapter5.htm

2014年2月14日

note 140214

M1~5 1um = 1mA

M6 , 1um = 1.6mA

電感距離 30~50

Vth~0.5V

2014年2月11日

VCO note

1.架構：Class-B , Class-C , Class-D , Class-B/C ...

push-push , colit..,

2.省電：transformer , current-reuse , bulk-driven tech , base 順向偏壓

3.雜訊抑制

4.調變方式：switch inductor /capacitor / resonant

5.chip area