Vanbus

A simple pub sub protocol (encoder/decoder) for embedded systems.

Addressing is by a path, similar(ish) to MQTT, where devices are addressed by paths composed of single byte/character path elements.

e.g. a/b/c.

The a path element is intended to be a group. The b path element is intended to be a device. The c path element is intended to be a field.

Message payloads are typed, and can be:

Boolean
Byte
Float (32-bit IEEE 754)
Short
Signed Short
Long
Signed Long

Encoding is intended to be endianness safe, and platform independent, and the library is intended to be universal - it's a basic C++ library, working on Arduino, but not relying on the arduino API.

Messages are written to, and parsed from, a buffer of bytes, so transport can be done in any manner desired, though the intention is to work well with PJON, and generally packetised/framed transport protocols.

Messages are processed as follows:

vanbus.receive(b, l); // b is a byte buffer, l is the length of the message

A device can subscribe to a topic/path, and dispatches callback functions on processing of relevant packets for further processing.

#include <vanbus.h>

Vanbus<2> vanbus; // template parameter is the number of callbacks to
                  // assign memory for

void l_c_b(VanbusMsg *m) {
  Serial.print(F("Ceiling light brightness change: "));
  Serial.println(m->getByte());
}

void l_c_s(VanbusMsg *m) {
  Serial.print(F("Ceiling light state change: "));
  Serial.println(m->getBit());
}

void setup() {
  vanbus.subscribe(l_c_b, 'l', 'c', 'b');
  vanbus.subscribe(l_c_s, 'l', 'c', 's');
}

Messages can be sent to paths which include a wildcard, '*', e.g. to send the same message to all devices in the same group.

uint8_t buf[8];
VanbusMsg msg;

// send all lights brightness 90 message
msg.path('l', 0x00, 'b');
msg.set(0x5A);
uint8_t l = msg.writeBytes(buf, 8);

vanbus.receive(buf, l);

nuxeh/vanbus

Vanbus