An Introduction To Squirrel Applications Example 3
In this example we will create a simple remote monitoring application that takes synchronous readings from multiple sensors and sends them to the cloud using the Initial State service. We will use a Hardware Abstraction Layer (HAL) to reference all hardware objects, and to organize our application code we will use a class. This code can be easily configured for use with an imp006 Breakout Kit, impExplorer Kit, impAccelerator Battery Powered Sensor Node or impC001 Breakout Board.
Beginner
This example will focus on writing Squirrel code. Please visit the Getting Started Guide on the Electric Imp Dev Center to learn how to configure your device with BlinkUp™ and how to use the Electric Imp IDE, impCentral™.
.HAL.nut
file in the repository that matches your hardware.
// HARDWARE ABSTRACTION LAYER
// ---------------------------------------------------
// HAL's are tables that map human readable names to
// the hardware objects used in the application.
// Copy and Paste Your HAL here
ExplorerKit_001 <- {
"LED_SPI" : hardware.spi257,
"SENSOR_AND_GROVE_I2C" : hardware.i2c89,
"TEMP_HUMID_I2C_ADDR" : 0xBE,
"ACCEL_I2C_ADDR" : 0x32,
"PRESSURE_I2C_ADDR" : 0xB8,
"POWER_GATE_AND_WAKE_PIN" : hardware.pin1,
"AD_GROVE1_DATA1" : hardware.pin2,
"AD_GROVE2_DATA1" : hardware.pin5
}
// REMOTE MONITORING APPLICATION CODE
// ---------------------------------------------------
// Application code, take readings from our sensors
// and send the data to the agent
class Application {
// Time in seconds to wait between readings
static READING_INTERVAL_SEC = 30;
// Accelerometer data rate in Hz
static ACCEL_DATARATE = 1;
// Hardware variables
i2c = ExplorerKit_001.SENSOR_AND_GROVE_I2C;
tempHumidAddr = ExplorerKit_001.TEMP_HUMID_I2C_ADDR;
accelAddr = ExplorerKit_001.ACCEL_I2C_ADDR;
// Sensor variables
tempHumid = null;
accel = null;
constructor() {...}
// Simple Remote Monitoring Application Device Code | |
// --------------------------------------------------- | |
// SENSOR LIBRARIES | |
// --------------------------------------------------- | |
// Libraries must be required before all other code | |
// Accelerometer Library | |
#require "LIS3DH.device.lib.nut:2.0.2" | |
// Temperature Humidity sensor Library | |
#require "HTS221.device.lib.nut:2.0.1" | |
// HARDWARE ABSTRACTION LAYER | |
// --------------------------------------------------- | |
// HAL's are tables that map human readable names to | |
// the hardware objects used in the application. | |
// Copy and Paste Your HAL here | |
// YOUR_HAL <- {...} | |
// REMOTE MONITORING APPLICATION CODE | |
// --------------------------------------------------- | |
// Application code, take readings from our sensors | |
// and send the data to the agent | |
class Application { | |
// Time in seconds to wait between readings | |
static READING_INTERVAL_SEC = 30; | |
// Accelerometer data rate in Hz | |
static ACCEL_DATARATE = 1; | |
// Hardware variables | |
i2c = null; // Replace with your sensori2c | |
tempHumidAddr = null; // Replace with your tempHumid i2c addr | |
accelAddr = null; // Replace with your accel i2c addr | |
// Sensor variables | |
tempHumid = null; | |
accel = null; | |
constructor() { | |
// Power save mode will reduce power consumption when the radio | |
// is idle, a good first step for saving power for battery | |
// powered devices. | |
// NOTE: Power save mode will add latency when sending data. | |
// Power save mode is not supported on impC001 and is not | |
// recommended for imp004m, so don't set for those types of imps. | |
local type = imp.info().type; | |
if (type != "imp004m" && type != "impC001") { | |
imp.setpowersave(true); | |
} | |
initializeSensors(); | |
} | |
function run() { | |
// Set up the reading table with a timestamp | |
local reading = { "time" : time() }; | |
// Add temperature and humidity readings | |
local result = tempHumid.read(); | |
if ("temperature" in result) reading.temperature <- result.temperature; | |
if ("humidity" in result) reading.humidity <- result.humidity; | |
// Add accelerometer readings | |
result = accel.getAccel(); | |
if ("x" in result) reading.accel_x <- result.x; | |
if ("y" in result) reading.accel_y <- result.y; | |
if ("z" in result) reading.accel_z <- result.z; | |
// Send readings to the agent | |
agent.send("reading", reading); | |
// Schedule the next reading | |
imp.wakeup(READING_INTERVAL_SEC, run.bindenv(this)) | |
} | |
function initializeSensors() { | |
// Configure i2c | |
i2c.configure(CLOCK_SPEED_400_KHZ); | |
// Initialize sensors | |
tempHumid = HTS221(i2c, tempHumidAddr); | |
accel = LIS3DH(i2c, accelAddr); | |
// Configure sensors to take readings | |
tempHumid.setMode(HTS221_MODE.ONE_SHOT); | |
accel.reset(); | |
accel.setMode(LIS3DH_MODE_LOW_POWER); | |
accel.setDataRate(ACCEL_DATARATE); | |
accel.enable(true); | |
} | |
} | |
// RUNTIME | |
// --------------------------------------------------- | |
server.log("Device running..."); | |
// Initialize application | |
app <- Application(); | |
// Start reading loop | |
app.run(); |
// Simple Remote Monitoring Application Agent Code | |
// --------------------------------------------------- | |
// CLOUD SERVICE LIBRARY | |
// --------------------------------------------------- | |
// Libraries must be required before all other code | |
// Initial State Library | |
#require "InitialState.class.nut:1.0.0" | |
// REMOTE MONITORING APPLICATION CODE | |
// --------------------------------------------------- | |
// Application code, listen for readings from device, | |
// when a reading is received send the data to Initial | |
// State | |
class Application { | |
// On Intial State website navigate to "my account" | |
// page find/create a "Streaming Access Key" | |
// Paste it into the variable below | |
static STREAMING_ACCESS_KEY = ""; | |
// Class variables | |
iState = null; | |
agentID = null; | |
constructor() { | |
// Initialize Initial State | |
iState = InitialState(STREAMING_ACCESS_KEY); | |
// The Initial State library will create a bucket | |
// using the agent ID | |
agentID = split(http.agenturl(), "/").top(); | |
// Let's log the agent ID here | |
server.log("Agent ID: " + agentID); | |
device.on("reading", readingHandler.bindenv(this)); | |
} | |
function readingHandler(reading) { | |
// Log the reading from the device. The reading is a | |
// table, so use JSON encodeing method convert to a string | |
server.log(http.jsonencode(reading)); | |
// Initial State requires the data in a specific structre | |
// Build an array with the data from our reading. | |
local events = []; | |
events.push({"key" : "temperature", "value" : reading.temperature, "epoch" : reading.time}); | |
events.push({"key" : "humidity", "value" : reading.humidity, "epoch" : reading.time}); | |
events.push({"key" : "accel_x", "value" : reading.accel_x, "epoch" : reading.time}); | |
events.push({"key" : "accel_y", "value" : reading.accel_y, "epoch" : reading.time}); | |
events.push({"key" : "accel_z", "value" : reading.accel_z, "epoch" : reading.time}); | |
// Send reading to Initial State | |
iState.sendEvents(events, function(err, resp) { | |
if (err != null) { | |
// We had trouble sending to Initial State, log the error | |
server.error("Error sending to Initial State: " + err); | |
} else { | |
// A successful send. The response is an empty string, so | |
// just log a generic send message | |
server.log("Reading sent to Initial State."); | |
} | |
}) | |
} | |
} | |
// RUNTIME | |
// --------------------------------------------------- | |
server.log("Agent running..."); | |
// Run the Application | |
Application(); |