/*****
 * RCR/T-433 Driver for RF Communications
 * Henry Chan (hc352)
 *
 * A driver for RF communication. Communication
 * will not block program execution. Assuming a
 * common bus, will only be able to transmit or
 * receive (not both) at a single time.
 *
 * Sample Receiving:
 * initRF();
 * while (checkError()) {
 *    receiveMessage(); // Keep trying to get message
 *    while(rf_state != RF_IDLE_S) {
 *       processByte(); // Until got message
 *    }
 *    decodePayload();
 *    // rf_payload[] will have payload
 * }
 *
 * Sample Transmitting:
 * initRF();
 * char pl[RF_PAYLOAD_SIZE];
 * pl[0] = 0xDE;
 * pl[1] = 0xAD;
 * pl[2] = 0xBE;
 * pl[3] = 0xEF;
 * // Until ready to send
 * sendMessage(pl);
 * while(rf_state != RF_IDLE_S) {
 *    processByte();
 * }
 * 
 *****/
#ifndef RFCOMM_H
#define RFCOMM_H

#include "portdeclarations.h"

// Payload size in bytes
#define RF_PAYLOAD_SIZE 4
// Start  marker size
#define RF_START_SIZE 1
// Sync sequence size
#define RF_SYNC_SIZE 4
// Preamble size
#define RF_PREAMBLE_SIZE (RF_START_SIZE+RF_SYNC_SIZE)
// Stop  marker size
#define RF_STOP_SIZE 1
// Start marker
#define RF_START_MARKER 0xCA
// Stop marker
#define RF_STOP_MARKER 0xD4
// Sync marker
#define RF_SYNC_MARKER 0xAA
// Frame size (preamble + payload*2)
#define RF_FRAME_SIZE (1+RF_PREAMBLE_SIZE+RF_STOP_SIZE+RF_PAYLOAD_SIZE*2)

#define RF_IDLE_S 0x01
#define RF_TX_S 0x02
#define RF_RX_S 0x03

// Use for compare match on timeout clock
#define RF_TX_TIMEOUT 253
#define RF_RX_TIMEOUT 234

/*****
 * Corresponding communications device is either
 * free or busy.
 *****/
extern char rf_state; // State of transmitter
extern char rf_payload[]; // Payload

/****
 * Sets RF into a known state
 ****/
void rf_init();

/****
 * Put message into buffer for sending
 ****/
char rf_send_msg(char buffer[]);

/****
 * Setup for receiving
 ****/
char rf_receive_msg();

/****
 * Checks for integrity of frame
 * Returns 0 if frame is alright
 * Returns 1 if frame is erroneous
 ****/
char rf_check_error();

/****
 * Processes a byte in the stream
 * Return 0 if uart was free and processed last command
 * Return 1 if uart is still busy
 ****/
char rf_process_byte();

/****
 * Decodes nibble from a byte in the data stream
 ****/
void rf_decode_pl();

/****
 * Clears the RF transmission channel by transmitting
 * a non-sync byte long enough to clear a noise-triggered
 * interrupt capture. A transmitter HIGH (output low) is
 * sent to adjust the receiver gain. After clearing the 
 * channel, sync bytes should be sent to resync the receiver.
 ****/
//void rf_clear_channel();

/****
 * Reset communications
 * Clear interrupts and flags
 ****/
void rf_reset();
#endif