Simple Chart
Last updated
Last updated
Visualize live and historical data in a chart from a single datastream. Applications include sensor data and binary event logging. Choose from data aggregation options of average and sum. The Y-axis scaling can be customized. Scrolling is an option, and you can connect missing data points.
See also the SuperChart widget that can handle multiple datastreams, shows the Y axis values, and supports the chart types of line, step, area, bar, state.
Simple Chart features:
line, stepped line, or bar chart types
plotting data resolutions: 1 min, 1 hour, or 1 day
plotting time ranges from 6 hours to 1 year
auto-scaled or fixed data axis
highlighted min/max values
easily reveal individual points via tap-n-hold
scrollable time axis
numerous styling settings
full-screen mode
Select or create a datastream of data type integer or double.
The widget has the following controls:
Time Ranges: tap to select a time range. These are configurable under the widget settings.
Full Screen: when enabled, the full screen icon will be displayed at the lower right of the widget. Tap to zoom the chart to the full screen.
The widget has extensive charting display options that are easily explored interactively with the preview. Chart types of line, step, area, bar, and binary are configurable for each datastream assigned.
Select a datastream which has numerical (i.e. of Int or Double) data type and comes from the device. Data that the app sends to the device is not registered. Simple Chart widget shows data from a single datastream. If you need to plot multiple datastreams in a single chart, check the Super Chart widget. By default the chart shows the average value (AVG) for each point on the chart, but you can change aggregation to (SUM) total of the incoming data. The time period covered by each point on the chart is defined by the selected Time Range/Resolution (see below).
Choose chart type (Line, Bar, or Step line) and its visual properties, like line width, color or gradient, axes style, etc. Note: when the gradient option is used, its color distribution is based on min/max properties of the selected datastream.
Select up to 7 time ranges you want to be able to switch between in the widget. Each time range button you select specifies its resolution - that is a period of time covered by each single point on a chart. Whenever there are multiple actual data writings coming from the device within the resolution period, that data is aggregated into one point (calculating average or total depending on the selection made in the Data section (see above).
There are a number of ways to define the range of values to be shown on a chart. Select option to:
use datastream min/max (available for AVG aggregation, not available for SUM aggregation)
auto scale the visual range to always fit all the data
0-Auto: auto-scale but always start from zero
define fixed min and max of the visual range
define delta: chart is auto-scaled, but its range never gets less than the delta set
Turn on Summary to show the average or total of all values presented on the chart in the top right corner. Note: summary style settings also define the style of selected value during tap-n-hold.
Show or hide a button at the bottom right to go to full-screen mode
Allow chart scrolling along the time axis. On scrolling, the chart and the summary are updated according to the new time range
Whether the line chart should connect missing points - that is all available points are connected in a line. Turn it off to visualize points without neighbours
Usually, just make sure that the data coming from the device is numerical. See more details on sending data here.
You can read the latest values from the datastreams assigned to the widget. For datastream V1 of data type double:
To get the latest datastream value assigned to V1:
To get the historical values assigned to datastream V1:
You can change the value of the datastream assigned to the widget with the hardware or HTTP API. The widget works best with historical data sent on a constant interval.
For a datastream V1 assigned the data type of double.
Hardware:
HTTP API:
Don't put Blynk.virtualWrite()into the void loop() as it can cause a flood of messages and your hardware will be disconnected. Send such updates only when necessary, use flags, or timers.
Sketch: Basic Sketch
Sketch: Set Property
Sketch: VirtualPinWrite
Sketch: VirtualPinRead
You can change certain properties of the Widget from your hardware. For that, use this command:
Where:
vPin is: virtual pin number the widget is assigned to
widgetProperty: property you want to change
propertyValue: value of the property you want to change
Don't put Blynk.setProperty()into the void loop() as it can cause a flood of messages and your hardware will be disconnected. Send such updates only when necessary, or use timers.
You can change the properties label, color, isDisabled, isHidden of the widget from your hardware, or via an HTTP API. The URL must be encoded, so spaces in labels must be replaced with %20, and color hexadecimal values in the HTTP API URL must include the hash # character urlencoded as %23.
Widget will be greyed out on UI and users won't be able to tap on it.
Widget will be hidden from dashboard. Design your UI so that it doesn't look weird when there is no widget.
GET https://{server_address}/external/api/update/property?token={your 32 char token}&pin={your vPin}&{property}={value}
The endpoint allows you to update the Datastream Property value via GET request. All widgets (both web and mobile) that are assigned to this datastream will inherit this property. The Datastream Property is persistent and will be stored forever until you change it with another value. In order to clear the property you need to clear the device data in device actions menu.
Example:
https://blynk.cloud/external/api/update/property?token=GVki9IC70vb3IqvsV0YD3el4y0OpneL1&pin=V2&label=My%20Label
https://blynk.cloud/external/api/update/property?token=GVki9IC70vb3IqvsV0YD3el4y0OpneL1&pin=V1&color=%23D3435C
https://blynk.cloud/external/api/update/property?token=GVki9IC70vb3IqvsV0YD3el4y0OpneL1&pin=V1&isDisabled=true
{property}
string
The property of the widget you want to update: label, color, isDisabled, isHidden
label
string
the text used as widget label
color
string
button color hexadecimal, must include the hash # character urlencoded as %23
isDisabled
string
true or false
isHidden
string
true or false
You can update your hardware to the latest datastream value from Blynk.Cloud after your hardware went offline, and then came online again. Use Blynk.syncVirtual() to update a single virtual pin, or Blynk.syncAll() to update all virtual pins. See State Syncing for more details.
