Sensors Skink

Demonstrates using the Skink environmental monitor backpack, with a web page displaying sensor readings.

SDK directory: apps/sensors/skink

API Features Demonstrated

Platforms

This app works on:

AMW004 - Zentri Mackerel evaluation board
AMW106 - Zentri Moray evaluation board
AVN4343 - Avnet IoT Starter Kit
NXP-SCCK - NXP Secure Cloud Connectivity Kit

Requirements and Prerequisites

This app requires a ZentriOS evaluation board. See the Platforms list above.

It also requires a Zentri Skink Environmental Sensor Backpack.

Resources

The initialization file skink.ini is packaged into the .zap file downloaded to the device.

The html file resources/skink.html is downloaded to the device.

Description

Demonstrates using the Skink environmental monitor backpack, with a web page displaying sensor readings.

The web page uses WebSockets to obtain sensor data from the device.

Usage Instructions

Open a ZentriOS serial terminal to the device. See Getting Started, Opening a ZentriOS Terminal.

When the app starts, terminal output is similar to the following:

> Starting Skink Environmental Sensor Demo
IPv4 address: 10.10.10.1
HTTP and REST API server listening on port: 80
SoftAP 'Skink' started on channel 1
Connect with a Wi-Fi client to: Skink / password
Using a browser, go to http://skink.com
[90:18:7C:34:CB:97 associated]
> [Opened: 0]
> Thermometer stream listener registered, streaming data
Temp = 2477

Air stream listener registered, streaming data
CO2  = 777 [ppm]
tVOC = 0 [ppb]

Light stream listener registered, streaming data
LUX = 171

Hygrometer stream listener registered, streaming data
RH = 320

Temp = 2476

RH = 320

Temp = 2477

CO2  = 777 [ppm]
tVOC = 0 [ppb]

LUX = 171

RH = 320

...

Connect a Wi-Fi client to the device Soft AP with SSID Skink as described, using the password password, then open a browser on the client and navigate to http://skink.com.

The skink web page is similar to the following:

Tap a sensor value to see a dynamic chart of the values over a period.

Implementation

main.c

zn_app_init

Loads the app settings with zn_load_app_settings to set up the HTTP Server and Soft AP.

Initializes the sensors with a call to initialize_sensors.

Registers HTTP server stream callbacks for each of the four sensors with calls to zn_hs_stream_register_callback.

The sensors are handled with similar code, so we'll discuss only the air sensor as a representative example.

initialize_sensors

For each sensor this involves a call to sensor_init.

air_stream_callback

The stream callbacks for all sensors are similar:

if HS_STREAM_LISTEN method: call zn_event_register_periodic to set up the periodic read event HS_STREAM_LISTEN method is received.
if HS_STREAM_UNLISTEN method: call zn_event_unregister
if HS_STREAM_READ method: read the sensor value with zn_hs_stream_read and then call zn_event_update_periodic to update the update period.

air_read_event_handler

The read handlers for all sensors are similar:

call get_sensor_data with the sensor id to read the data
if successful, send the data with a call to the corresponding send_<sensor>_data function

send_air_sensor_data

Perform the appropriate unit conversions to the input data, then call the general send_data to send the data.

send_data

Encode the data into a json buffer and call zn_hs_stream_write_listener to write to the appropriate stream.

get_sensor_data

The same function gets sensor data for all sensors, with sensors distinguished by the sensor id argument. This demonstrates the value of the sensor library abstraction layer.

Source

See: