BTLE/BTLE.h

/*
 * Copyright (C) 2013 Florian Echtler <floe@butterbrot.org>
 * Eddystone part Copyright (c) 2018 Pavel Brychta <pablo@xpablo.cz>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 3 as published by the Free Software Foundation.
*/

#ifndef _BTLE_H_
#define _BTLE_H_

#include "Arduino.h"
#include <RF24.h>

// float as used on the nRF8001 and nRF51822 platforms
// and on the "nRF Master Control Panel" and "nRF Temp 2.0" apps.
// This float representation has the first 8 bits as a base-10 exponent
// and the last 24 bits as the mantissa.
typedef int32_t nRF_Float;

// Service UUIDs used on the nRF8001 and nRF51822 platforms
#define NRF_TEMPERATURE_SERVICE_UUID		0x1809
#define NRF_BATTERY_SERVICE_UUID			0x180F
#define NRF_DEVICE_INFORMATION_SERVICE_UUID 0x180A

// helper struct for sending temperature as BT service data
struct nrf_service_data {
	int16_t   service_uuid;
	nRF_Float value;
};

// advertisement PDU
struct btle_adv_pdu {

	// packet header
	uint8_t pdu_type; // PDU type
	uint8_t pl_size;  // payload size

	// MAC address
	uint8_t mac[6];

	// payload (including 3 bytes for CRC)
	uint8_t payload[24];
};

// payload chunk in advertisement PDU payload
struct btle_pdu_chunk {
	uint8_t size;
	uint8_t type;
	uint8_t data[];
};

// helper macro to access chunk at specific offset
#define chunk(x,y) ((btle_pdu_chunk*)(x.payload+y))


class BTLE {

	public:

		BTLE( RF24* _radio );

		// convert an arduino float to a nRF_Float
		static nRF_Float to_nRF_Float(float t);

		void begin( const char* _name ); // set BTLE-compatible radio parameters & name

		void setChannel( uint8_t num ); // set the current channel (from 36 to 38)
		void hopChannel();              // hop to the next channel

		// Broadcast an advertisement packet with a specific data type
		// Standardized data types can be seen here:
		// https://www.bluetooth.org/en-us/specification/assigned-numbers/generic-access-profile
		bool advertise( uint8_t data_type, void* buf, uint8_t len );

		// Broadcast an advertisement packet with optional payload
		// Data type will be 0xFF (Manufacturer Specific Data)
		bool advertise( void* buf, uint8_t len );
		bool listen( int timeout = 100 );         // listen for advertisement packets (if true: result = buffer)

		// Broadcast an Eddystone URL packet
		bool eddystoneURL(const char *url);

		btle_adv_pdu buffer;  // buffer for received BTLE packet (also used for outgoing!)

	private:

		void whiten( uint8_t len );
		void swapbuf( uint8_t len );
		void crc( uint8_t len, uint8_t* dst );
		uint8_t encodeURL(uint8_t* encodedUrl, const char *rawUrl);

		RF24* radio;       // pointer to the RF24 object managing the radio
		uint8_t current;   // current channel index
    const char* name;  // name of local device
};

#endif // _BTLE_H_