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easyRadio.md

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LPRS easyRadio (eRIC) Radio Modules

  • KEYWORDS: Module,Wireless,Radio,Transceiver,easyRadio

eRIC module

The 'easy Radio Integrated Controller' (eRIC) radio transceiver module is based on the Texas Instruments CC430F5137 System-on-Chip. It combines a high performance RF transceiver, RF band pass filters (BPF), an MSP430 microcontroller, 32Kb flash memory, non-volatile flash storage, temperature sensor, and a low drop voltage regulator. The device operates on the International licence exempt Industrial, Scientific and Medical (ISM) radio bands.

While these modules can be programmed with their own code, they come pre-installed with the easyRadio firmware, which allows communication over a serial interface. A driver this is in the [[easyRadio.js]] module.

See LPRS's site for more information.

Wiring Up

eRIC module breakout

It's easier to buy an eRIC module in a breakout board. You then just need to connect the following wires:

Label Espruino Pico Notes
GND GND
3.3v/VCC 3.3v The eRIC module can run from +2.4V to +6V
RX/SDO B7 (or any UART RX pin) Transmits data, see below
TX/SDI B6 (or any UART TX pin) Receives data, see below

NOTE:

  • While the breakout board is marked with RX and TX pins, unlike many peripherals this refers to the type of pin the eRIC's should be connected to, not the actual type of pin. So the RX pin actually transmits data.
  • If running the Pico when not connected to a computer, the console interface will automatically move to Serial1, disabling the easyRadio driver (see Troubleshooting for more info and how to stop that behaviour). This will allow you to program and debug your Espruino Pico using a remote easyRadio module, but may not be what you intended.

Software

The easyRadio modules default to 19200 baud. All you need to do is set up the serial port and initialise the module.

Serial1.setup(19200, {rx:B7, tx:B6});
var eric = require("easyRadio").connect(Serial1, function(d) {
  // Called when data received
  console.log("Got "+JSON.stringify(d));
});

Send data with:

eric.send("Hello World");

And the callback you supply at initialisation is called whenever data is received. For instance a second eRIC module might report the following in response to the last command:

Got "H"
Got "e"
Got "l"
Got "l"
Got "o "
Got "W"
Got "o"
Got "rl"
Got "d"

You might for instance want to process only one line of data at a time:

function gotData() {
  console.log("Got "+JSON.stringify(d));
}

Serial1.setup(19200, {rx:B7, tx:B6});
var ericData = "";
var eric = require("easyRadio").connect(Serial1, function(d) {
  ericData+=d;
  var i = ericData.indexOf("\n");
  while (i>=0) {
    gotData(ericData.substr(0,i));
    ericData = ericData.substr(i+1);
    i = ericData.indexOf("\n");
  }
});

By default one eRIC module will broadcast to any other eRIC modules in range. To change this behaviour you can change the group ID of specific modules (to a value between 1 and 65535) with eric.setGroupID(32). Then, only modules with the same group ID will communicate.

eRIC modules also provide other functionality such as a temperature sensor and EEPROM. See the reference below for more information about these - note that the easyRadio module is asynchronous, so functions will return immediately without a return value and will call a callback argument with the result or an error at some later time.

// Quickly
eric.getTemperature(print);
// prints "null 22.4"

// Properly
eric.getTemperature(function(err, temp) {
  if (err) console.log("We got an error! "+err);
  else console.log("Temperature is "+temp);
});

Remote Connection to Espruino

It's easy to use eRIC modules to communicate with an Espruino board as if it was connected by wire:

  • Wire an eRIC module to an Espruino as above
  • Write the following into Espruino
Serial1.setup(19200, {rx:B7, tx:B6});
var realReset = reset;
var reset = function() {}
  • Type save();
  • Disconnect the Espruino from the PC, and power it from something else (this will move the console on to Serial1).
  • Now wire a second eRIC module to a USB-Serial converter and plug it to your computer
  • Open the Web IDE, go to Settings, Communications and set Baud Rate to 19200
  • Connect the Web IDE to your USB-Serial converter - you should now be able to program the Espruino remotely as before.

Note: Espruino's reset() function would reset the baud rate to 9600 baud so it has to be disabled in this case.

Reference

  • APPEND_JSDOC: easyRadio.js

Using

  • APPEND_USES: easyRadio

Buying

LPRS maintain a list of distributors here