DIY-Multiprotocol-TX-Module/Multiprotocol/Bayang_Rx_nrf24l01.ino

/*
 This project is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

Multiprotocol is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with Multiprotocol.  If not, see <http://www.gnu.org/licenses/>.
 */

#if defined(BAYANG_RX_NRF24L01_INO)

#include "iface_xn297.h"

#define BAYANG_RX_PACKET_SIZE		15
#define BAYANG_RX_RF_NUM_CHANNELS	4
#define BAYANG_RX_RF_BIND_CHANNEL	0
#define BAYANG_RX_ADDRESS_LENGTH	5

enum {
	BAYANG_RX_BIND = 0,
	BAYANG_RX_DATA
};

static void __attribute__((unused)) Bayang_Rx_RF_init()
{
	const uint8_t bind_address[BAYANG_RX_ADDRESS_LENGTH] = { 0,0,0,0,0 };
	XN297_Configure(XN297_CRCEN, XN297_SCRAMBLED, XN297_1M);
	XN297_SetTXAddr(bind_address, BAYANG_RX_ADDRESS_LENGTH);
	XN297_SetRXAddr(bind_address, BAYANG_RX_PACKET_SIZE);
	XN297_RFChannel(BAYANG_RX_RF_BIND_CHANNEL);
	XN297_SetTxRxMode(TXRX_OFF);
	XN297_SetTxRxMode(RX_EN);
}

static uint8_t __attribute__((unused)) Bayang_Rx_check_validity() {
	uint8_t sum = packet[0];
	for (uint8_t i = 1; i < BAYANG_RX_PACKET_SIZE - 1; i++)
		sum += packet[i];
	return sum == packet[14];
}

static void __attribute__((unused)) Bayang_Rx_build_telemetry_packet()
{
	uint32_t bits = 0;
	uint8_t bitsavailable = 0;
	uint8_t idx = 0;

	packet_in[idx++] = RX_LQI;
	packet_in[idx++] = RX_LQI>>1;	// no RSSI: 125..0
	packet_in[idx++] = 0;			// start channel
	packet_in[idx++] = 10;			// number of channels in packet

	// convert & pack channels
	for (uint8_t i = 0; i < packet_in[3]; i++) {
		uint32_t val = CHANNEL_MIN_100;
		if (i < 4) {
			// AETR
			//val = (((packet[4 + i * 2] & ~0x7C) << 8) | packet[5 + i * 2]) << 1;
			val=packet[4 + i * 2]&0x03;
			val=(val<<8)+packet[5 + i * 2];
			val=((val+128)<<3)/5;
		} else if (i == 4 || i == 5) {
			val=packet[i==4?1:13];
			val=((val+32)<<5)/5;						// extra analog channel
		} else if (((i == 6) && (packet[2] & 0x08)) ||	// flip
				 ((i == 7) && (packet[2] & 0x01)) ||	// rth
				 ((i == 8) && (packet[2] & 0x20)) ||	// picture
				 ((i == 9) && (packet[2] & 0x10))) {	// video
			// set channel to 100% if feature is enabled
			val = CHANNEL_MAX_100;
		}
		bits |= val << bitsavailable;
		bitsavailable += 11;
		while (bitsavailable >= 8) {
			packet_in[idx++] = bits & 0xff;
			bits >>= 8;
			bitsavailable -= 8;
		}
	}
}

void BAYANG_RX_init()
{
	uint8_t i;
	Bayang_Rx_RF_init();
	hopping_frequency_no = 0;
	rx_data_started = false;
	rx_data_received = false;
	
	if (IS_BIND_IN_PROGRESS) {
		phase = BAYANG_RX_BIND;
	}
	else {
		uint16_t temp = BAYANG_RX_EEPROM_OFFSET;
		for (i = 0; i < 5; i++)
			rx_tx_addr[i] = eeprom_read_byte((EE_ADDR)temp++);
		for (i = 0; i < BAYANG_RX_RF_NUM_CHANNELS; i++)
			hopping_frequency[i] = eeprom_read_byte((EE_ADDR)temp++);
		//XN297_HoppingCalib(BAYANG_RX_RF_NUM_CHANNELS);
		XN297_SetTXAddr(rx_tx_addr, BAYANG_RX_ADDRESS_LENGTH);
		XN297_SetRXAddr(rx_tx_addr, BAYANG_RX_PACKET_SIZE);
		phase = BAYANG_RX_DATA;
	}
}

uint16_t BAYANG_RX_callback()
{
	uint8_t i;
	static int8_t read_retry;

	switch (phase)
	{
		case BAYANG_RX_BIND:
			if(IS_BIND_DONE)
			{
				BAYANG_RX_init();	// Abort bind
				break;
			}
			if ( XN297_IsRX() )
			{
				debugln("RX");
				// data received from TX
				if (XN297_ReadPayload(packet, BAYANG_RX_PACKET_SIZE) && ( packet[0] == 0xA4 || packet[0] == 0xA2 ) && Bayang_Rx_check_validity())
				{
					// store tx info into eeprom
					uint16_t temp = BAYANG_RX_EEPROM_OFFSET;
					for (i = 0; i < 5; i++) {
						rx_tx_addr[i] = packet[i + 1];
						eeprom_write_byte((EE_ADDR)temp++, rx_tx_addr[i]);
					}
					for (i = 0; i < 4; i++) {
						hopping_frequency[i] = packet[i + 6];
						eeprom_write_byte((EE_ADDR)temp++, hopping_frequency[i]);
					}
					//XN297_HoppingCalib(BAYANG_RX_RF_NUM_CHANNELS);
					XN297_SetTXAddr(rx_tx_addr, BAYANG_RX_ADDRESS_LENGTH);
					XN297_SetRXAddr(rx_tx_addr, BAYANG_RX_PACKET_SIZE);
					BIND_DONE;
					phase = BAYANG_RX_DATA;
				}
				XN297_SetTxRxMode(RX_EN);
			}
			break;
		case BAYANG_RX_DATA:
			if ( XN297_IsRX() ) {
				if (XN297_ReadPayload(packet, BAYANG_RX_PACKET_SIZE) && packet[0] == 0xA5 && Bayang_Rx_check_validity()) {
					if ((telemetry_link & 0x7F) == 0) {
						Bayang_Rx_build_telemetry_packet();
						telemetry_link = 1;
						#ifdef SEND_CPPM
							if(sub_protocol>0)
								telemetry_link |= 0x80;	// Disable telemetry output
						#endif
					}
					rx_data_started = true;
					rx_data_received = true;
					read_retry = 8;
					pps_counter++;
				}
			}
			// packets per second
			if (millis() - pps_timer >= 1000) {
				pps_timer = millis();
				debugln("%d pps", pps_counter);
				RX_LQI = pps_counter >> 1;
				pps_counter = 0;
			}
			// frequency hopping
			if (read_retry++ >= 8) {
				hopping_frequency_no++;
				if (hopping_frequency_no >= BAYANG_RX_RF_NUM_CHANNELS)
					hopping_frequency_no = 0;
				XN297_Hopping(hopping_frequency_no);
				XN297_SetTxRxMode(RX_EN);
				if (rx_data_started)
				{
					if(rx_data_received)
					{ // In sync
						rx_data_received = false;
						read_retry = 5;
						return 1500;
					}
					else
					{ // packet lost
						read_retry = 0;
						if(RX_LQI==0)	// communication lost
							rx_data_started=false;
					}
				}
				else
					read_retry = -16; // retry longer until first packet is caught
			}
			return 250;
	}
	return 1000;
}

#endif