Andrew Boyson
/
iot
Backing up an unused program in case of future need
ntp.cpp
- Committer:
- andrewboyson
- Date:
- 2016-04-13
- Revision:
- 0:09f915e6f9f6
- Child:
- 2:06fa34661f19
File content as of revision 0:09f915e6f9f6:
#include <mbed.h> #include "log.h" #include "esp.h" #include "wifi.h" #include "time.h" #include "io.h" #include "at.h" #define GET_TIME_INTERVAL 600 #define RETRY_INTERVAL 60 #define ID 0 #define SIXTEENTHS_TO_ADD 1 Timer timer; struct Packet { /* LI: 00 no warning; 01 last minute has 61 seconds; 10 last minute has 59 seconds; 11 alarm condition (clock not synchronized) VN: 3 = 011 Mode: 3 = 011 for client request; 4 = 100 for server reply 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |LI | VN |Mode | Stratum | Poll | Precision | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 1|1 0 1 1| Mode: If the Mode field of the request is 3 (client), the reply is set to 4 (server). If this field is set to 1 (symmetric active), the reply is set to 2 (symmetric passive). This allows clients configured in either client (NTP mode 3) or symmetric active (NTP mode 1) to interoperate successfully, even if configured in possibly suboptimal ways. Poll: signed integer indicating the minimum interval between transmitted messages, in seconds as a power of two. For instance, a value of six indicates a minimum interval of 64 seconds. Precision: signed integer indicating the precision of the various clocks, in seconds to the nearest power of two. The value must be rounded to the next larger power of two; for instance, a 50-Hz (20 ms) or 60-Hz (16.67 ms) power-frequency clock would be assigned the value -5 (31.25 ms), while a 1000-Hz (1 ms) crystal-controlled clock would be assigned the value -9 (1.95 ms). Root Delay (rootdelay): Total round-trip delay to the reference clock, in NTP short format (16bitseconds; 16bit fraction). Root Dispersion (rootdisp): Total dispersion to the reference clock, in NTP short format (16bitseconds; 16bit fraction).. */ union { uint32_t FirstLine; struct { unsigned Mode : 3; unsigned VN : 3; unsigned LI : 2; uint8_t Stratum; int8_t Poll; int8_t Precision; }; }; uint32_t RootDelay; uint32_t Dispersion; uint32_t RefIdentifier; uint64_t RefTimeStamp; uint64_t OriTimeStamp; uint64_t RecTimeStamp; uint64_t TraTimeStamp; }; static struct Packet packet; static uint64_t ntohll(uint64_t n) { int testInt = 0x0001; //Big end contains 0x00; little end contains 0x01 int *pTestInt = &testInt; char *pTestByte = (char*)pTestInt; char testByte = *pTestByte; //fetch the first byte if (testByte == 0x00) return n; //If the first byte is the big end then host and network have same endianess union ull { uint64_t Whole; char Bytes[8]; }; union ull h; h.Whole = n; char t; t = h.Bytes[7]; h.Bytes[7] = h.Bytes[0]; h.Bytes[0] = t; t = h.Bytes[6]; h.Bytes[6] = h.Bytes[1]; h.Bytes[1] = t; t = h.Bytes[5]; h.Bytes[5] = h.Bytes[2]; h.Bytes[2] = t; t = h.Bytes[4]; h.Bytes[4] = h.Bytes[3]; h.Bytes[3] = t; return h.Whole; } uint64_t getTimeAsNtp() { uint64_t ntpTime = 2208988800ULL << 32; ntpTime += TimeGet16ths() << 28; return ntpTime; } void setTimeAsNtp(uint64_t ntpTime) { ntpTime -= 2208988800ULL << 32; uint64_t time16ths = (ntpTime >> 28) + SIXTEENTHS_TO_ADD; TimeSet16ths(time16ths); } void NtpInit() { EspIpdReserved[ID] = true; } int preparePacket() { memset(&packet, 0, sizeof(packet)); packet.LI = 0; packet.VN = 1; packet.Mode = 3; //Client packet.TraTimeStamp = ntohll(getTimeAsNtp()); return 0; } int handlePacket() { //Handle the reply char leap = packet.LI; char version = packet.VN; char mode = packet.Mode; char stratum = packet.Stratum; if (leap == 3) { LogF("Remote clock has a fault\r\n"); return -1; } if (version < 1) { LogF("Version is %d\r\n", version); return -1; } if (mode != 4) { LogF("Mode is %d\r\n", mode); return -1; } if (stratum == 0) { LogF("Received Kiss of Death packet (stratum is 0)\r\n"); return -1; } /* See http://www.eecis.udel.edu/~mills/time.html for timestamp calculations Ori ----t1---------t4---- RTC \ / -------t2---t3------- NTP Rec Tra offset (RTC - NTP) = (t1 + t4)/2 - (t2 + t3)/2 ==> [(t1 - t2) + (t4 - t3)] / 2 delay = (t4 - t1) - (t3 - t2) */ //Set the RTC setTimeAsNtp(ntohll(packet.RecTimeStamp)); return 0; } int NtpIdConnectStatus = AT_NONE; static void outgoingMain() { if (AtBusy()) return; if (!WifiStarted()) return; static int firstAttempt = true; static int result = AT_NONE; if (NtpIdConnectStatus == AT_SUCCESS) { int retryAfterFailure = timer.read() > RETRY_INTERVAL && result != AT_SUCCESS; int repeat = timer.read() > GET_TIME_INTERVAL; if (firstAttempt || retryAfterFailure || repeat) { preparePacket(); AtSendData(ID, sizeof(packet), &packet, &result); firstAttempt = false; timer.reset(); timer.start(); } } else { AtConnectId(ID, "UDP", "192.168.1.3", 123, &packet, sizeof(packet), &NtpIdConnectStatus); } } static void incomingMain() { if (EspDataAvailable == ESP_AVAILABLE && EspIpdId == ID) { if (EspIpdLength == sizeof(packet)) handlePacket(); else LogF("Incorrect NTP packet length of %d bytes", EspIpdLength); } } int NtpMain() { outgoingMain(); incomingMain(); return 0; }