Arduino Library

note-arduino is the official Arduino library for communicating with the Notecard over serial or I2C. The library works on any Arduino compatible microcontroller, and can be installed from the Arduino Library Manager or PlatformIO.

See note-arduino in action in these accelerator projects.

Installation

You can install and use the note-arduino library from Arduino IDE or PlatformIO using the steps below.

Usage

#include <Notecard.h>

#include <Notecard.h>

With the library included, you next must initialize the Notecard over serial or I2C.

• Serial Configuration
• I2C Configuration

Serial Configuration

To initialize the Notecard over Serial, instantiate a Notecard object, then use the begin() method and provide the Serial object as a parameter. The Notecard object will initialize the serial bus on your behalf.

Default Serial Initialization

Notecard notecard;

void setup(void) {
    # Initialize Notecard serial interface (with defaults)
    notecard.begin(Serial1);
}

Serial Initialization with Baud Rate

Notecard notecard;

void setup(void) {
    # Initialize Notecard serial interface
    notecard.begin(Serial1, 9600);
}

I2C Configuration

To initialize the Notecard over I2C, instantiate a Notecard object, then use the begin() method with zero, one, two, or three parameters. Use as many parameters as needed to match your implementation.

Default I2C Initialization

Notecard notecard;

void setup (void) {
    # Initialize Notecard I2C interface (with defaults)
    notecard.begin();
}

I2C Initialization with Address

uint32_t i2cAddress = 0x24;

Notecard notecard;

void setup (void) {
    # Initialize Notecard I2C interface
    notecard.begin(i2cAddress);
}

note

By passing an I2C address to notecard.begin() you are not assigning an address to the Notecard. Instead, you are telling the Arduino library to look for a Notecard at an I2C address that you set on the Notecard with a card.io request.

I2C Initialization with Address and Max Transaction Length

uint32_t i2cAddress = 0x17;
uint32_t i2cMax = 32;

Notecard notecard;

void setup(void) {
    # Initialize Notecard I2C interface
    notecard.begin(i2cAddress, i2cMax);
}

I2C Initialization with Address, Max Transaction Length and I2C Bus

uint32_t i2cAddress = 0x17;
uint32_t i2cMax = 32;

Notecard notecard;

void setup(void) {
    # Initialize Notecard I2C interface
    notecard.begin(i2cAddress, i2cMax, Wire);
}

Debug Mode

If you're connected to the Serial Monitor (located in the "Tools" menu of Arduino IDE), you can put the Notecard library in debug mode using the setDebugOutputStream method, which will output raw JSON requests and responses.

#define serialDebug Serial
Notecard notecard;

void setup() {
  // Initialize Debug Output
  serialDebug.begin(115200);
  while (!serialDebug) {
    ; // wait for serial port to connect. Needed for native USB
  }
  notecard.setDebugOutputStream(serialDebug);
}

Sending Notecard Requests

Whether using Serial or I2C, sending Notecard requests and reading responses follows the same pattern:

1. Create a JSON object that includes a valid Notecard API Request.
2. Call one of the notecard methods and pass in the request JSON object.
3. If you called a method that returns a response, make sure the response contains the data you need.

#define productUID "com.your-company.your-name:your_product"
Notecard notecard;

void setup() {
    J *req = notecard.newRequest("hub.set");
    if (req) {
        JAddStringToObject(req, "product", productUID);
        JAddStringToObject(req, "mode", "continuous");
        JAddBoolToObject(req, "sync", true);
        if (!notecard.sendRequest(req)) {
            notecard.logDebug("FATAL: Failed to configure Notecard!\n");
            while(1);
        }
    }
}

notecard Methods

The Notecard provides a variety of methods for performing requests.

• newRequest() creates a JSON (J) object for the specified Notecard request. This method returns a JSON object with the req key set.

J *req = notecard.newRequest("card.status");

• sendRequest() sends a JSON (J) request to the Notecard.

J *req = notecard.newRequest("hub.sync");
if (req) {
    notecard.sendRequest(req);
}

• requestAndResponse() sends a JSON (J) request to the Notecard, and additionally returns the Notecard's JSON response in a J object that you can parse.

J *req = notecard.newRequest("card.status");
if (req) {
    J* rsp = notecard.requestAndResponse(req);
    // do something with the response
    notecard.deleteResponse(rsp);
}

note

In some situations, you may need to send the Notecard a request and you cannot receive a response. For example, when using card.attn request's sleep argument to disable a host MCU, the host will be disabled and incapable of receiving a response.

For these scenarios the note-arduino library provides a newCommand method. The newCommand method creates a new JSON (J) object for sending the Notecard a command rather than a request. You can send commands to the Notecard using the same sendRequest method you use for requests.

COPY

J *cmd = notecard.newCommand("card.attn");
if (cmd) {
    JAddStringToObject(cmd, "mode", "sleep");
    JAddNumberToObject(cmd, "seconds", 3600);
    notecard.sendRequest(cmd);
}

JSON Handling

The note-arduino library uses a J JSON object for many of its APIs, and provides a number of functions for helping you create and parse J JSON objects.

Creating JSON Objects

The note-arduino library's sendRequest and requestAndResponse functions both expect a J JSON object as an argument. You can create the initial J object with a call to newRequest, which allocates the appropriate memory and returns a JSON object that contains a "req" key-value pair.

J *req = notecard.newRequest("example.request");
if (req) {
    // At this point req represents a JSON object with the structure:
    // { "req": "example.request" }
}

From there, the following functions are available for helping you populate your JSON object with the data you need.

• JAddBoolToObject
• JAddNumberToObject
• JAddStringToObject
• JAddObjectToObject
• JAddArrayToObject
• JAddItemToArray

To see how to use these functions, suppose you need to create a J JSON object that contains the following JSON data.

{
    "req": "example.request",
    "key-1": true,
    "key-2": 2,
    "key-3", "3",
    "key-4": {
        "key-a": ["a"]
    }
}

The code below constructs the above JSON structure, and then passes that object to the Notecard using sendRequest.

J *req = notecard.newRequest("example.request");
if (req) {
    JAddBoolToObject(req, "key-1", true);
    JAddNumberToObject(req, "key-2", 2);
    JAddStringToObject(req, "key-3", "3");
    J* key4 = JAddObjectToObject(req, "key-4");
    J* keyA = JAddArrayToObject(key4, "key-a");
    JAddItemToArray(keyA, JCreateString("a"));

    notecard.sendRequest(req);
}

note

The note-arduino library includes several functions for creating "items" of a JSON object, such as JCreateArray, JCreateObject, JCreateNumber, JCreateBool, and JCreateString.

You only need these functions if you're using an API that requires a JSON item as an argument, such as JAddItemToArray.

Parsing JSON Objects

The note-arduino library's requestAndResponse function returns a J JSON object that contains response data from the Notecard. For example, the code below calls performs a card.status request on the Notecard, and and stores the returned data in a J object.

if (J *req = notecard.newRequest("card.status")) {
    J *rsp = notecard.requestAndResponse(req);
    notecard.logDebug(JConvertToJSONString(rsp));
    notecard.deleteResponse(rsp);
}

After requestAndResponse runs, the JSON that rsp points at will have the structure below.

{
  "connected": true,
  "status": "{normal}",
  "storage": 2,
  "time": 1667924973,
  "cell": true
}

There are a number of functions you can use to parse individual fields out of a JSON object.

• JIsPresent
• JGetBool
• JGetInt
• JGetNumber
• JGetObject
• JGetString

For example, the following code shows an example of how to access fields from the card.status response.

char status[20];
if (J *req = notecard.newRequest("card.status")) {
    J *rsp = notecard.requestAndResponse(req);
    notecard.logDebug(JConvertToJSONString(rsp));

    bool connected = JGetBool(rsp, "connected");
    char *tempStatus = JGetString(rsp, "status");
    strlcpy(status, tempStatus, sizeof(status));
    int storage = JGetInt(rsp, "storage");
    int time = JGetInt(rsp, "time");
    bool cell = JGetBool(rsp, "cell");

    notecard.deleteResponse(rsp);
}

When the response contains nested objects you can parse them using JGetObject. For example, the file.changes request returns a JSON object with a structure that looks like the one below.

{
  "info": {
    "data.qo": {
      "total": 1
    },
    "data.qi": {
      "total": 2
    },
    "total": 3
  }
}

Given this response, you could use the following code to parse out the total from within the "data.qo" object.

if (J *req = notecard.newRequest("file.changes")) {
    J *rsp = notecard.requestAndResponse(req);
    notecard.logDebug(JConvertToJSONString(rsp));

    J *info = JGetObject(rsp, "info");
    J *data = JGetObject(info, "data.qo");
    int total = JGetInt(data, "total");
    notecard.logDebugf("Total: %d", total); // 1

    notecard.deleteResponse(rsp);
}

Examples

We provide several examples for using note-arduino in a number of different scenarios. If you're using Arduino IDE you can access the examples from the File > Examples > Blues Wireless Notecard menu.

If you're using PlatformIO you can copy the source code for the examples from the links below.

• Example 0: Libraryless Communication
  • Learn how to communicate with a Notecard in Arduino without using the note-arduino library.
• Example 1: Notecard Basics
  • Learn the basics of communicating with a Notecard, including running a hub.set and note.add request.
• Example 2: Periodic Communications
  • Learn how to communicate with a Notecard in periodic mode, gathering sensor measurements "offline", and performing uploads on a periodic basis.
• Example 3: Inbound Polling
  • Learn how to use the Notecard to poll for inbound messages at a defined interval.
• Example 4: Inbound Interrupts
  • Learn how to use the Notecard to manage an inbound queue of messages using interrupts.
• Example 5: Using Templates
  • Learn how to use Note templates to send outbound Notes that use minimal bandwidth.
• Example 6: Sensor Tutorial
  • Learn how to collect sensor data and send it to the cloud using the Notecard. This code is also used by the sensor tutorial.
• Example 7: Power Control
  • Learn how the Notecard can be used to put a host to sleep, save some state for the host, wake it up periodically and return saved state to the host.
• Example 8: Send/Receive Binary Data
  • Learn how to both send and receive large binary data objects with the Notecard.
• Example 9: Send/Receive Binary Data (Chunked)
  • Learn how to send and receive large binary data objects that are split into smaller "chunks" for more efficient processing.

API Reference

Library Classes

Notecard Class Reference

The class that stores state and functions for interacting with the Blues Notecard.

Class Notecard

begin (I2C)

Initialize the Notecard for I2C. This function configures the Notecard to use the I2C bus for communication with the host.

Notecard notecard;
...

// Initialize I2C using default parameters
notecard.begin();

Notecard notecard;
...

// Initialize I2C specifying all parameters
notecard.begin(0x17, 30, Wire);

begin (Serial)

Initialize the Notecard for Serial communication. This function configures the Notecard to use Serial for communication with the host.

Notecard notecard;
...

// Initialize Serial using default parameters
notecard.begin(Serial1);

Notecard notecard;
...

// Initialize Serial specifying all parameters
notecard.begin(Serial1, 9600);

setDebugOutputStream

Set the debug output source. This function takes a Stream object (for example, Serial) and configures it as a source for writing debug messages during development.

Notecard notecard;
...

notecard.setDebugOutputStream(Serial);

clearDebugOutputStream

Clear the debug output source.

Notecard notecard;
...

notecard.clearDebugOutputStream();

newRequest

Creates a new request object for population by the host. This function accepts a request string (for example, "note.add") and initializes a JSON object to return to the host.

note

The newRequest function allocates memory to create a JSON object, which can fail if system resources are low. We recommend using the following pattern to check for this condition, which works because newRequest returns nullptr if the request fails.

COPY

if (J *req = notecard.newRequest("hub.sync")) {
  ...
}

Notecard notecard;
...

J *req = notecard.newRequest("card.status");

Returns

A pointer to a J JSON Object populated with the request name.

See also

• requestAndResponse()
• sendRequest()

newCommand

Creates a new command object for population by the host. This function accepts a command string (for example, "note.add") and initializes a JSON object to return to the host.

note

The newCommand function allocates memory to create a JSON object, which can fail if system resources are low. We recommend using the following pattern to check for this condition, which works because newCommand returns nullptr if the request fails.

COPY

if (J *req = notecard.newCommand("hub.sync")) {
  ...
}

Notecard notecard;
...

J *req = notecard.newCommand("card.status");

Returns

A pointer to a J JSON Object populated with the request name.

See also

• sendRequest()

sendRequest

Sends a request to the Notecard. This function takes a populated J JSON request object and sends it to the Notecard.

Notecard notecard;
...

if (J *req = notecard.newRequest("hub.sync")) {
    notecard.sendRequest(req);
}

Returns

true if the message was successfully sent to the Notecard, false if there was an error.

See also

• newRequest()

sendRequestWithRetry

Sends a request to the Notecard, retrying for timeoutSeconds until it succeeds or it times out. This function takes a populated J JSON request object and sends it to the Notecard.

Notecard notecard;
...

if (J *req = notecard.newRequest("hub.sync")) {
    notecard.sendRequestWithRetry(req, 5);
}

Returns

true if the message was successfully sent to the Notecard, false if there was an error.

requestAndResponse

Sends a request to the Notecard and returns the JSON Response. This function takes a populated J JSON request object and sends it to the Notecard.

Notecard notecard;
...

if (J *req = notecard.newRequest("card.status")) {
    J *rsp = notecard.requestAndResponse(req);
    notecard.logDebug(JConvertToJSONString(rsp));
    notecard.deleteResponse(rsp);
}

Returns

J * JSON object pointer with the response from the Notecard, or NULL if there was an error sending the request.

See also

• deleteResponse()
• newRequest()

warning

You are responsible for managing the memory associated with the JSON response object.

requestAndResponseWithRetry

Sends a request to the Notecard, retrying for timeoutSeconds until it succeeds or it times out and returns the JSON Response. This function takes a populated J JSON request object and sends it to the Notecard.

Notecard notecard;
...

if (J *req = notecard.newRequest("card.status")) {
    J *rsp = notecard.requestAndResponseWithRetry(req, 5);
    notecard.logDebug(JConvertToJSONString(rsp));
    notecard.deleteResponse(rsp);
}

Returns

J * JSON object pointer with the response from the Notecard, or NULL if there was an error sending the request.

See also

• deleteResponse()
• newRequest()

warning

You are responsible for managing the memory associated with the JSON response object.

deleteResponse

Deletes a J JSON response object from memory.

Notecard notecard;
...

if (J *req = notecard.newRequest("card.status")) {
    J *rsp = notecard.requestAndResponse(req);
    notecard.logDebug(JConvertToJSONString(rsp));
    notecard.deleteResponse(rsp);
}

See also

• requestAndResponse()

logDebug

Write a message to the serial debug stream.

Notecard notecard;
...

notecard.logDebug("Hello, World!\n");

logDebugf

Write a formatted message to the serial debug stream.

Notecard notecard;
bool excited;
...

notecard.logDebugf("High-%d!\n", (excited ? 10 : 5));

debugSyncStatus

Periodically show Notecard sync status, returning true if something was displayed to the debug stream.

Notecard notecard;
...

// Poll for programmatic level (3) sync status every 1.5s (1500ms)
notecard.debugSyncStatus(1500, 3);

Returns

true if a pending response was displayed to the debug stream.

warning

Specific log messages are NOT considered to be part of the stable API, and therefore should NEVER be programmed against. There is no guarantee of consistency of message or logging level for any given message.

responseError

Determines if there is an error string present in a response object.

Notecard notecard;
...

if (J *req = notecard.newRequest("card.status")) {
    J *rsp = notecard.requestAndResponse(req);
    if (notecard.responseError(rsp)) {
        notecard.logDebug("Error response returned!");
    } else {
        // process response
    }
    notecard.deleteResponse(rsp);
}

Returns

true if the response object contains an error.