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118 lines
4.1 KiB
118 lines
4.1 KiB
/*
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* Copyright (C) 2025 by Jonathan Naylor G4KLX and contributors
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* SX1255 support: Karel Kadlec (OK1LBC) <xkk@post.cz>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef SX1255Controller_H
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#define SX1255Controller_H
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#include "SoundCardController.h"
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#include <atomic>
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#include <string>
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#include <thread>
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/*
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* CSX1255Controller - D-Star modem using a Semtech SX1255 direct-I/Q HAT.
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*
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* The SX1255 is a 410-510 MHz transceiver that exposes zero/low-IF I/Q over an
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* I2S ALSA sound card (the "genericstereoaudiocodec" overlay) and is configured
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* over Linux SPI. The D-Star protocol engine (GMSK modulation, frame sync, FEC,
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* interleaving and scrambling) is inherited from CSoundCardController and is
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* therefore identical to the existing Sound Card modem.
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*
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* This class replaces only the audio transport:
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*
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* RX: 125 kHz S32_LE interleaved I/Q -> DC block -> complex mixer
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* (RXShift) -> LPF + decimate by 5 -> FM discriminator -> fractional
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* resample to 48 kHz -> CSoundCardController baseband demodulator.
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*
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* TX: CSoundCardController GMSK baseband at 48 kHz -> FM modulator ->
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* fractional upsample to 125 kHz -> S32_LE interleaved I/Q.
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*
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* SPI is used to program the RX/TX frequencies, the chip configuration
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* registers and the RX/TX enable mode register (0x00). The TX front-end is
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* only enabled while D-Star data is actually being transmitted so that an idle
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* repeater does not radiate an unmodulated carrier.
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*/
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class CSX1255Controller : public CSoundCardController {
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public:
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CSX1255Controller(const std::string& rxDevice, const std::string& txDevice,
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const std::string& spiDevice,
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unsigned int rxFrequency, unsigned int txFrequency,
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float rxShiftHz, float txDeviationHz,
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bool rxInvert, bool txInvert,
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float rxLevel, float txLevel,
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unsigned int txDelay, unsigned int txTail,
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unsigned int spiSpeed, int resetGpio,
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const std::string& resetChip, unsigned int resetLine,
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const std::string& pttChip, unsigned int pttLine, bool pttInvert);
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virtual ~CSX1255Controller();
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virtual bool start() override;
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virtual bool isTX() override;
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virtual void stop() override;
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private:
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void rxThread();
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void txThread();
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bool spiOpen();
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void spiClose();
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bool spiReset();
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bool spiInitChip();
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bool spiSetFrequency(bool tx, unsigned int freqHz);
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bool spiSetMode(unsigned char mode);
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bool alsaOpen();
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void alsaClose();
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bool pttOpen();
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void pttClose();
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void pttSet(bool active);
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// Configuration
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std::string m_rxDevice;
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std::string m_txDevice;
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std::string m_spiDevice;
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unsigned int m_rxFrequency;
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unsigned int m_txFrequency;
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float m_rxShiftHz;
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float m_txDeviationHz;
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unsigned int m_spiSpeed;
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int m_resetGpio;
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std::string m_resetChip;
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unsigned int m_resetLine;
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std::string m_pttChip;
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unsigned int m_pttLine;
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bool m_pttInvert;
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// Runtime state
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int m_spiFd;
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snd_pcm_t* m_pcmRx;
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snd_pcm_t* m_pcmTx;
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std::thread m_rxThread;
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std::thread m_txThread;
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std::atomic<bool> m_txEnabled; // SX1255 TX front-end enable state
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std::atomic<bool> m_txActive; // True while D-Star data is flowing out
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void* m_pttChipHandle; // gpiod_chip*
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void* m_pttRequest; // gpiod_line_request*
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bool m_pttAsserted;
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};
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#endif
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