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Merge pull request #459 from GreyRook/add-timezone

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refactor of time synchronization protocol
This commit is contained in:
Verkehrsrot 2019-10-04 15:51:09 +02:00 committed by GitHub
commit dd2dcf32cb
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5 changed files with 30 additions and 20 deletions
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8
include/timesync.h
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@ -7,13 +7,15 @@
#include "timekeeper.h"
//#define TIME_SYNC_TRIGGER 100 // threshold for time sync [milliseconds]
#define TIME_SYNC_FRAME_LENGTH 0x05 // timeserver answer frame length [bytes]
#define TIME_SYNC_FRAME_LENGTH 0x07 // timeserver answer frame length [bytes]
#define TIME_SYNC_FIXUP 4 // calibration to fixup processing time [milliseconds]
void timesync_init(void);
void send_timesync_req(void);
int recv_timesync_ans(const uint8_t seq_no, const uint8_t buf[], const uint8_t buf_len);
int recv_timesync_ans(const uint8_t buf[], uint8_t buf_len);
void process_timesync_req(void *taskparameter);
void store_time_sync_req(uint32_t t_millisec);
#endif
#endif

4
src/Timeserver/Nodered-Timeserver.json
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@ -187,7 +187,7 @@
"type": "function",
"z": "449c1517.e25f4c",
"name": "Timeserver Logic",
"func": "/* LoRaWAN Timeserver\n\nconstruct 5 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte meaning\n1..4 current second (from epoch time 1970)\n5 1/250ths fractions of current second\n\nFPort = sequence number (taken from node's time_sync_req)\n\n*/\n\nfunction timecompare(a, b) {\n \n const timeA = a.time;\n const timeB = b.time;\n\n let comparison = 0;\n if (timeA > timeB) {\n comparison = 1;\n } else if (timeA < timeB) {\n comparison = -1;\n }\n return comparison;\n}\n\nlet confidence = 2000; // max millisecond diff gateway time to server time\n\n// guess if we have received a valid time_sync_req command\nif (msg.payload.payload_raw.length != 1)\n return;\n\nvar deviceMsg = { payload: msg.payload.dev_id };\nvar seqNo = msg.payload.payload_raw[0];\nvar seqNoMsg = { payload: seqNo };\nvar gateway_list = msg.payload.metadata.gateways;\n\n// filter all gateway timestamps that have milliseconds part (which we assume have a \".\")\nvar gateways = gateway_list.filter(function (element) {\n return (element.time.includes(\".\"));\n});\n\nvar gateway_time = gateways.map(gw => {\n return {\n time: new Date(gw.time),\n eui: gw.gtw_id,\n }\n });\nvar server_time = new Date(msg.payload.metadata.time);\n\n// validate all gateway timestamps against lorawan server_time (which is assumed to be recent)\nvar gw_timestamps = gateway_time.filter(function (element) {\n return ((element.time > (server_time - confidence) && element.time <= server_time));\n});\n\n// if no timestamp left, we have no valid one and exit\nif (gw_timestamps.length === 0) {\n var notavailMsg = { payload: \"n/a\" };\n var notimeMsg = { payload: 0xff }; \n var buf2 = Buffer.alloc(1);\n msg.payload = new Buffer(buf2.fill(0xff));\n return [notavailMsg, notavailMsg, deviceMsg, seqNoMsg, msg];}\n\n// sort time array in ascending order to find most recent timestamp for time answer\ngw_timestamps.sort(timecompare);\n\nvar timestamp = gw_timestamps[0].time;\nvar eui = gw_timestamps[0].eui;\nvar offset = server_time - timestamp;\n\nvar seconds = Math.floor(timestamp/1000);\nvar fractions = (timestamp % 1000) / 4;\n\nlet buf = new ArrayBuffer(5);\nnew DataView(buf).setUint32(0, seconds);\nnew DataView(buf).setUint8(4, fractions);\n\nmsg.payload = new Buffer(new Uint8Array(buf));\nmsg.port = seqNo;\nvar euiMsg = { payload: eui };\nvar offsetMsg = { payload: offset };\n\nreturn [euiMsg, offsetMsg, deviceMsg, seqNoMsg, msg];",
"func": "/* LoRaWAN Timeserver\n\nconstruct 5 byte timesync_answer from gateway timestamp and node's time_sync_req\n\nbyte meaning\n1..4 current second (from epoch time 1970)\n5 1/250ths fractions of current second\n\nFPort = sequence number (taken from node's time_sync_req)\n\n*/\n\nfunction timecompare(a, b) {\n \n const timeA = a.time;\n const timeB = b.time;\n\n let comparison = 0;\n if (timeA > timeB) {\n comparison = 1;\n } else if (timeA < timeB) {\n comparison = -1;\n }\n return comparison;\n}\n\nlet confidence = 2000; // max millisecond diff gateway time to server time\n\n// guess if we have received a valid time_sync_req command\nif (msg.payload.payload_raw.length != 1)\n return;\n\nvar deviceMsg = { payload: msg.payload.dev_id };\nvar seqNo = msg.payload[0];\nvar seqNoMsg = { payload: seqNo };\nvar gateway_list = msg.payload.metadata.gateways;\n\n// filter all gateway timestamps that have milliseconds part (which we assume have a \".\")\nvar gateways = gateway_list.filter(function (element) {\n return (element.time.includes(\".\"));\n});\n\nvar gateway_time = gateways.map(gw => {\n return {\n time: new Date(gw.time),\n eui: gw.gtw_id,\n }\n });\nvar server_time = new Date(msg.payload.metadata.time);\n\n// validate all gateway timestamps against lorawan server_time (which is assumed to be recent)\nvar gw_timestamps = gateway_time.filter(function (element) {\n return ((element.time > (server_time - confidence) && element.time <= server_time));\n});\n\n// if no timestamp left, we have no valid one and exit\nif (gw_timestamps.length === 0) {\n var notavailMsg = { payload: \"n/a\" };\n var notimeMsg = { payload: 0xff }; \n var buf2 = Buffer.alloc(1);\n msg.payload = new Buffer(buf2.fill(0xff));\n return [notavailMsg, notavailMsg, deviceMsg, seqNoMsg, msg];}\n\n// sort time array in ascending order to find most recent timestamp for time answer\ngw_timestamps.sort(timecompare);\n\nvar timestamp = gw_timestamps[0].time;\nvar eui = gw_timestamps[0].eui;\nvar offset = server_time - timestamp;\n\nvar seconds = Math.floor(timestamp/1000);\nvar fractions = (timestamp % 1000) / 4;\n\nlet buf = new ArrayBuffer(7);\nnew DataView(buf).setUint8(0, seqNo);\n// Timezone (in 15min steps)\nvar timezone = 8; // CET = UTC+2h\nnew DataView(buf).setUint8(1, timezone);\nnew DataView(buf).setUint32(2, seconds);\nnew DataView(buf).setUint8(6, fractions);\n\nmsg.payload = new Buffer(new Uint8Array(buf));\nmsg.port = 9;\nvar euiMsg = { payload: eui };\nvar offsetMsg = { payload: offset };\n\nreturn [euiMsg, offsetMsg, deviceMsg, seqNoMsg, msg];",
"outputs": 5,
"noerr": 0,
"x": 350,
@ -384,4 +384,4 @@
"disabled": false,
"hidden": false
}
]
]

4
src/lorawan.cpp
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@ -561,8 +561,8 @@ void myRxCallback(void *pUserData, uint8_t port, const uint8_t *pMsg,
#if (TIME_SYNC_LORASERVER)
// valid timesync answer -> call timesync processor
if ((port >= TIMEANSWERPORT_MIN) && (port <= TIMEANSWERPORT_MAX)) {
recv_timesync_ans(port, pMsg, nMsg);
if (port == TIMEPORT) {
recv_timesync_ans(pMsg, nMsg);
break;
}
#endif

8
src/paxcounter.conf
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@ -30,7 +30,7 @@
* |< Scan Window > |< Scan Window > | ... |< Scan Window > |
* |< Scan Interval >|< Scan Interval >| ... |< Scan Interval >|
* |< Scan duration >|
*
*
* Scan duration sets how long scanning should be going on, before starting a new scan cycle. 0 means infinite (default).
* Scan window sets how much of the interval should be occupied by scanning. Should be >= BLESCANINTERVAL.
* Scan interval is how long scanning should be done on each channel. BLE uses 3 channels for advertising.
@ -97,9 +97,9 @@
#define BEACONPORT 6 // beacon alarms
#define BMEPORT 7 // BME680 sensor
#define BATTPORT 8 // battery voltage
#define TIMEPORT 9 // time query
#define TIMEANSWERPORT_MIN 0xA0 // time answer, start of port range
#define TIMEANSWERPORT_MAX 0xDF // time answer, end of port range
#define TIMEPORT 9 // time query and response
#define TIMEDIFFPORT 13 // time adjust diff
#define TIMEREQUEST_MAX_SEQNO 250 // time answer, start of port range
#define SENSOR1PORT 10 // user sensor #1
#define SENSOR2PORT 11 // user sensor #2
#define SENSOR3PORT 12 // user sensor #3

26
src/timesync.cpp
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@ -25,7 +25,7 @@ typedef std::chrono::duration<long long int, std::ratio<1, 1000>>
TaskHandle_t timeSyncReqTask = NULL;
static uint8_t time_sync_seqNo = random(TIMEANSWERPORT_MIN, TIMEANSWERPORT_MAX);
static uint8_t time_sync_seqNo = 0;
static bool timeSyncPending = false;
static myClock_timepoint time_sync_tx[TIME_SYNC_SAMPLES];
static myClock_timepoint time_sync_rx[TIME_SYNC_SAMPLES];
@ -93,9 +93,10 @@ void process_timesync_req(void *taskparameter) {
time_point_cast<milliseconds>(time_sync_tx[k]);
// wrap around seqNo, keeping it in time port range
time_sync_seqNo = (time_sync_seqNo < TIMEANSWERPORT_MAX)
? time_sync_seqNo + 1
: TIMEANSWERPORT_MIN;
time_sync_seqNo++;
if(time_sync_seqNo > TIMEREQUEST_MAX_SEQNO) {
time_sync_seqNo = 0;
}
if (i < TIME_SYNC_SAMPLES - 1) {
// wait until next cycle
@ -154,7 +155,9 @@ void store_time_sync_req(uint32_t timestamp) {
}
// process timeserver timestamp answer, called from lorawan.cpp
int recv_timesync_ans(const uint8_t seq_no, const uint8_t buf[], const uint8_t buf_len) {
int recv_timesync_ans(const uint8_t buf[], const uint8_t buf_len) {
uint8_t seq_no = buf[0];
buf++;
// if no timesync handshake is pending then exit
if (!timeSyncPending)
@ -177,9 +180,14 @@ int recv_timesync_ans(const uint8_t seq_no, const uint8_t buf[], const uint8_t b
// the 5th byte contains the fractional seconds in 2^-8 second steps
// (= 1/250th sec), we convert this to ms
uint16_t timestamp_msec = 4 * buf[4];
// pointers to 4 bytes containing UTC seconds since unix epoch, msb
uint16_t timestamp_msec = 4 * buf[6];
// pointers to 4 bytes 4 bytes containing UTC seconds since unix epoch, msb
uint32_t timestamp_sec, *timestamp_ptr;
uint32_t timezone_sec;
// extract timezone from buffer (in 15min steps, one step being 15min * 60s = 900s)
timezone_sec = buf[0]*900;
buf++;
// convert buffer to uint32_t, octet order is big endian
timestamp_ptr = (uint32_t *)buf;
@ -187,7 +195,7 @@ int recv_timesync_ans(const uint8_t seq_no, const uint8_t buf[], const uint8_t b
timestamp_sec = __builtin_bswap32(*timestamp_ptr);
// construct the timepoint when message was seen on gateway
time_sync_rx[k] += seconds(timestamp_sec) + milliseconds(timestamp_msec);
time_sync_rx[k] += seconds(timestamp_sec+timezone_sec) + milliseconds(timestamp_msec);
// we guess timepoint is recent if it newer than code compile date
if (timeIsValid(myClock::to_time_t(time_sync_rx[k]))) {
@ -218,4 +226,4 @@ void timesync_init() {
1); // CPU core
}
#endif
#endif