Time & Location Requests

Once the Notecard is connected to a cell network or GPS, there are a number of requests available for obtaining the time, location, and using the onboard GPS module for location tracking.

Obtaining the Current Time and Date

To obtain the current time, expressed as a Unix epoch value, use the card.time request. Note: Upon power-up, the Notecard must complete a sync to Notehub in order to obtain time and location data.

{"req": "card.time"}

Sending this request yields a response that includes the current UNIX Epoch time, local time zone, minutes East of GMT, latitude (lat), longitude (lon), and country.

{
  "time":    1598478570,
  "area":    "Beverly, MA",
  "zone":    "CDT,America/New York",
  "minutes": -300,
  "lat":     42.577600,
  "lon":     -70.871340,
  "country": "US",
}

note

Tower Location vs. Notecard Location

It's important to note that the location values returned by a card.time request correspond to the cellular tower to which the Notecard last connected. This may differ widely from the physical location of the Notecard. For greater accuracy of location, you'll want to use card.location APIs described below.

Until the Notecard has connected to a cellular network, it does not know the time. In those cases, card.location requests respond with a zone value of UTC,Unknown.

{"zone":"UTC,Unknown"}

Using Cell Tower & Wi-Fi Triangulation

For improved location accuracy without using GPS, the Notecard provides optional triangulation capabilities that can gather information about surrounding cell towers and/or local Wi-Fi access points to ascertain a location upon each new Notehub session.

Due to the low-power nature of the Notecard, triangulation-derived location data is only available if the Notecard has detected motion with its onboard accelerometer (unless overridden by card.triangulate arguments).

Cell tower triangulation is only available with the Cellular Notecard and should be used sparingly if your device is battery-powered, as it can add 1-2 minutes of connection time whenever the Notecard powers on the cellular modem to establish a connection with Notehub.

Wi-Fi triangulation is available with both the Cellular and Wi-Fi Notecards. Unlike cell tower triangulation, it adds only 1-2 seconds of processing time, uses minimal power, can be nearly as accurate as a GPS-derived location, but does require additional configuration (see below).

warning

Wi-Fi triangulation is an experimental, technical preview feature that is free for use today, but may use Consumption Credits in the future. Blues Wireless reserves the right to rate limit excessive Wi-Fi triangulation requests at our discretion.

Enabling Triangulation

To enable triangulation, use the card.triangulate request with the mode argument set to wifi, cell, or both, separated by a comma:

COPY
{
  "req": "card.triangulate",
  "mode": "wifi,cell"
}

This request will return an object confirming that triangulation is enabled with the mode provided, and a motion field indicating the last time device movement was detected.

COPY
{
  "mode": "wifi,cell",
  "motion": 1606761044
}

Depending on your requirements, you may also need to change the frequency at which triangulation data is processed on Notehub. The default is "Daily", which means at most triangulation data will be processed once per day. This option is available in the Settings of your Notehub project and also updatable as the _tri_mins environment variable:

note

A card.triangulate request does not itself perform triangulate with the Notecard. Rather, it gathers cell tower and/or Wi-Fi access point data that Notehub uses to perform device triangulation.

In addition, this feature does not affect the location data returned by a card.location request, but is intended to increase the accuracy of location data sent from Notehub to any Routes defined in a project. See Viewing Triangulation Location Data in Notehub below to understand where triangulation-based location data appears in Notehub events.

Providing Wi-Fi Information to the Notecard

If your host has an onboard Wi-Fi module, you can perform a manual access point scan and send this information to the Cellular Notecard using the text argument. Sending this data to the Cellular Notecard is required to enable Wi-Fi triangulation, while the Wi-Fi Notecard has triangulation enabled by default.

The format of the text field must be a newline-terminated list of Wi-Fi access points that follows a pattern similar to the ESP32's AT+CWLAP command output.

COPY
{
  "req": "card.triangulate",
  "text": "+CWLAP:(4,\"Blues\",-51,\"74:ac:b9:12:12:f8\",1)\n+CWLAP:(3,\"AAAA-62DD\",-70,\"6c:55:e8:91:62:e1\",11)\n+CWLAP:(4,\"Blues\",-81,\"74:ac:b9:11:12:23\",1)\n+CWLAP:(4,\"Blues\",-82,\"74:ac:a9:12:19:48\",11)\n+CWLAP:(4,\"Free Parking\",-83,\"02:18:4a:11:60:31\",6)\n+CWLAP:(5,\"GO\",-84,\"01:13:6a:13:90:30\",6)\n+CWLAP:(4,\"AAAA-5C62-2.4\",-85,\"d8:97:ba:7b:fd:60\",1)\n+CWLAP:(3,\"DIRECT-a5-HP MLP50\",-86,\"fa:da:0c:1b:16:a5\",6)\n+CWLAP:(3,\"DIRECT-c6-HP M182 LaserJet\",-88,\"da:12:65:44:31:c6\",6)\n\n"
}

This request will return an object with the current triangulation configuration parameters, and a length field indicating the size of the text buffer provided in the request.

COPY
{
  "usb":    true,
  "mode":   "wifi",
  "length": 398,
  "on":     true,
  "time":   1606770857,
  "motion": 1606770581
}

note

Use the Notecard Auxiliary Wi-Fi Arduino library for an easier way of programmatically pulling a list of Wi-Fi access points with your Wi-Fi enabled host MCU and sending them to the Notecard.

Using Triangulation with the Wi-Fi Notecard

The Wi-Fi Notecard supports Wi-Fi triangulation only and is enabled by default, with no end-user configuration required. Every event in Notehub sent by a Wi-Fi Notecard will have triangulation location data appended.

Viewing Triangulation Location Data in Notehub

Enabling cell tower or Wi-Fi triangulation does not affect the location data returned by a card.location request (which is reserved solely for GPS location data). However, when triangulation is enabled, additional triangulation-derived fields with lat/lon coordinates will appear in Notehub events, prepended with tri_, and may be routed. For example:

COPY
"tri_when": 1656011112,
"tri_lat": 43.07113895,
"tri_lon": -89.43272533,
"tri_location": "Shorewood Hills WI",
"tri_country": "US",
"tri_timezone": "America/Chicago",
"tri_points": 16,

Configuring USB Power and Motion-based Triangulation

The card.triangulate request provides options for configuring the Notecard based on its power state and movement. Set the usb argument to true to instruct the Notecard to only perform triangulation when connected to USB power, and set on to true if you want the Notecard to triangulate even when the device has not moved. Both flags require the set argument in order to take effect.

COPY
{
  "req":  "card.triangulate",
  "mode": "wifi,cell",
  "on":   true,
  "usb":  true,
  "set":  true
}

This request will return an object with the current triangulation configuration parameters, a motion field indicating the time of the last device movement, and time field indicating the time of the last triangulation scan.

COPY
{
  "mode":   "wifi,cell",
  "usb":    true,
  "on":     true,
  "time":   1606758961,
  "motion": 1606761044
}

Disabling Triangulation

To turn triangulation off, set the mode argument to -:

COPY
{
  "req":  "card.triangulate",
  "mode": "-"
}

This request will return an object with no mode argument, indicating that triangulation is disabled. The motion and time fields may still be present after triangulation is disabled.

COPY
{"motion": 1606761044}

Working with GPS on the Notecard

The Notecard includes an onboard GPS module that can be used for location tracking, when paired with an appropriate antenna. To conserve power, the GPS module on the Notecard is off, by default. You can confirm this with the card.location request:

{"req":"card.location"}

Which will return the following:

{
 "status": "GPS is off {gps-inactive}",
 "mode": "off"
}

When using GPS mode, you'll want to decide whether your application should enable GPS periodically to conserve battery at the cost of accuracy between readings, or continuously in real-time.

note

The Notecard will not turn on the GPS module until it has made a successful cellular connection upon startup to obtain the current time. Once the Notecard has the time, GPS is available for use, regardless of the state of a cellular connection.

There are also other functions on the Notecard that require the time to be set.

Sampling GPS Readings With Periodic Mode

If you prefer to enable GPS readings on an interval, use periodic mode. In this mode, the Notecard enables GPS at a frequency you define using either a set number of seconds or using a voltage-variable value. In both cases, regardless of the periodic value, the GPS module will only turn on to update the location if the Notecard has moved since the last time GPS was enabled. The 'seconds' value sets the minimum interval at which the Notecard will enable its GPS.

Sampling at Predefined Intervals

For example, to enable the Notecard's GPS no more frequently than once every 600 seconds (10 minutes), set mode to periodic and use the seconds argument in a card.location.mode request:

{
 "req": "card.location.mode",
 "mode": "periodic",
 "seconds": 600
}

This will return an object confirming that the Notecard is in periodic mode and that GPS should be enabled no more frequently than once every 600 seconds:

{
 "mode": "periodic",
 "seconds": 600
}

Once enabled, use the card.location request to monitor connection status and location.

{"req":  "card.location"}

While waiting for the Notecard to obtain a GPS fix, expect to see intermediate status messages in response to card.location requests.

// When the module is still inactive
{
  "status": "GPS inactive {gps-inactive}",
  "mode":   "periodic"
}
 
// When the module has started
{
  "status": "GPS started {gps-active} {gps-active}",
  "mode":   "periodic"
}
 
// When the module is active, but searching for GPS
{
    "status": "GPS search (19 sec, 41dB SNR, 5 sats) {gps-active}
                {gps-signal} {gps-sats}",
    "mode":   "periodic"
}

You may see several variations of the second message before the module obtains a fix. Once obtained, future card.location requests include the current Notecard latitude (lat) and longitude (lon) values, as well as the Unix epoch time that location was captured.

{
  "status": "GPS updated (58 sec, 41dB SNR, 9 sats) {gps-active}
            {gps-signal} {gps-sats} {gps}",
  "mode":   "periodic",
  "lat":    42.577600,
  "lon":    -70.871340,
  "time":   1598554399
}

note

To preserve battery, when the Notecard is in periodic mode, GPS is only enabled if the built-in accelerometer detects movement since the last GPS enable. If the Notecard has not moved, a card.location request will indicate that GPS is inactive and provide the last location reading.

COPY

{
 "status": "GPS inactive {gps-inactive} {gps}",
 "mode": "periodic",
 "lat": 42.5776,
 "lon": -70.87134,
 "time": 1598557149
}

Tracking GPS Location Readings

When operating in periodic mode, use the card.location.track request to configure the Notecard to store GPS readings in a Notefile. Note that the behavior in this section only applies to the capture of location events. The rules for how and when those events sync are the same as general sync settings defined with hub.set.

{
 "req": "card.location.track",
 "start": true
}

This will return an object confirming that tracking mode has started and the minimum duration in seconds between Notes being placed in a Notefile. The seconds value is the value set in a request to card.location.mode.

{
 "seconds": 10,
 "start": true
}

By default, tracking notes are placed into a Notefile named _track.qo. To define your own Notefile, use the file argument.

{
 "req": "card.location.track",
 "start": true,
 "file": "locations.qo"
}

note

Tracking data is available to view in Notehub, once synced, and includes a number of helpful fields that can be Routed to your cloud applications.

COPY

{
 "bearing": 194.8890307950282,
 "distance": 5.591816976119877,
 "seconds": 36,
 "hdop": 1,
 "temperature": 49.625,
 "time": 1598560691,
 "usb": true,
 "velocity": 0.014337992246461224,
 "voltage": 4.727260437757979
}

By default, tracking data will only be captured if the Notecard detects motion. To add periodic tracking Notes when there is no movement, use the heartbeat argument. You can also use the optional hours argument to capture heartbeat tracking notes at a rate that differs from the rate when there is motion.

{
 "req": "card.location.track",
 "start": true,
 "heartbeat": true,
 "hours": 1
}

If you wish to initiate a sync to Notehub each time a tracking Note is added to the Notecard, set the sync field to true (As of Notecard firmware v1.5.5):

{
 "req": "card.location.track",
 "sync": true
}

To turn tracking mode off, set the stop argument to true.

{
 "req": "card.location.track",
 "stop": true
}

Always-on GPS With Continuous Mode

To set your Notecard to GPS Continuous mode, use the card.location.mode request:

{
 "req": "card.location.mode",
 "mode": "continuous"
}

Which will return an object confirming that the Notecard is in continuous mode:

{"mode": "continuous"}

Once enabled, use the card.location request to monitor connection status and location:

{"req": "card.location"}

While waiting for the Notecard to obtain a GPS fix, expect to see intermediate status messages in response to card.location requests. Note: the Notecard will not turn on the GPS module until it has made a successful cellular connection upon startup to obtain the current time. Once the Notecard has the time, GPS is available for use, regardless of the state of a cellular connection.

// When the module is still inactive
{
  "status": "GPS inactive {gps-inactive}",
  "mode":   "continuous"
}
 
// When the module is active, but searching for GPS
{
    "status": "GPS search (19 sec, 41dB SNR, 5 sats) {gps-active}
                {gps-signal} {gps-sats}",
    "mode":   "continuous"
}

You may see several variations of the status message before the module obtains a fix. Once obtained, future card.location requests include the current Notecard latitude (lat) and longitude (lon) values, as well as the Unix epoch time that location was captured.

{
  "status": "GPS updated (58 sec, 41dB SNR, 9 sats) {gps-active}
            {gps-signal} {gps-sats} {gps}",
  "mode":   "continuous",
  "lat":    42.577600,
  "lon":    -70.871340,
  "time":   1598554399
}

warning

Continuous Cellular & Continuous GPS

The Notecard does not support running both a continuous cellular connection ({"req":"hub.set", "mode":"continuous"}) and continuous GPS. If you attempt to set both cellular and GPS to continuous mode, the Notecard will return an error. This applies both to card.location.mode when the cellular connection is continuous, as well as hub.set if GPS has been set in continuous mode.

COPY

{"err": "cannot simultaneously use continuous card.location.mode and hub.set modes"}

Determining the Current GPS Mode

At any point, the GPS mode of the Notecard can be obtained by calling the card.location.mode command with no arguments.

{ "req":  "card.location.mode" }

Geofencing With the Notecard

The Notecard can be configured to trigger an immediate sync to Notehub when the device moves beyond a geofence you define. Use the lat and lon arguments to set the center, and the max argument to specify the number of meters from the center to set the geofence. You can also optionally pass the minutes argument to specify a number of minutes the Notecard must be outside of the geofence before its location is tracked. The default value for minutes is 5.

{
 "req": "card.location.mode",
 "mode": "periodic",
 "lat": 42.5776,
 "lon": -70.87134,
 "max": 100,
 "minutes": 2
}

This will return an object confirming that the geofence is enabled using the parameters provided.

{
 "max": 100,
 "mode": "periodic",
 "lat": 42.5776,
 "lon": -70.87134,
 "minutes": 2
}

Disabling GPS

When you no longer need to capture GPS data from the Notecard, turn it off with a card.location.mode request and mode field set to off.

{
 "req": "card.location.mode",
 "mode": "off"
}

Which will return an object confirming that GPS is off:

{"mode": "off"}

note

Even after GPS has been disabled, the Notecard keeps the last location obtained, which can be retrieved at any time with a card.location request.

COPY

{"req": "card.location"}

COPY

{
 "status": "GPS is off {gps-inactive} {gps}",
 "mode": "off",
 "lat": 42.5776,
 "lon": -70.87134,
 "time": 1598555070
}

If you wish to delete the last known location stored in the Notecard, use the delete argument in a card.location.mode request.

{
 "req": "card.location.mode",
 "delete": true
}

Subsequent requests to card.location no longer provide location data, until GPS is re-enabled and a new reading is captured.

{
 "status": "GPS is off {gps-inactive} {gps}",
 "mode": "off"
}