portapack-mayhem/firmware/application/hw/max2839.cpp

/*
 * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
 * Copyright (C) 2023 Great Scott Gadgets
 *
 * This file is part of PortaPack.
 *
 * This program 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 2, or (at your option)
 * any later version.
 *
 * This program 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 this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

#include "max2839.hpp"

#include "hackrf_hal.hpp"
#include "hackrf_gpio.hpp"
using namespace hackrf::one;

#include "ch.h"
#include "hal.h"

#include <algorithm>

namespace max2839 {

namespace lna {

using namespace max283x::lna;

constexpr std::array<uint8_t, 8> lookup_8db_steps {
	0b11, 0b11, 0b10, 0b10,
	0b01, 0b00, 0b00, 0b00
};

static uint_fast8_t gain_ordinal(const int8_t db) {
	const auto db_sat = gain_db_range.clip(db);
	return lna::lookup_8db_steps[(db_sat >> 3) & 7];
}

} /* namespace lna */

namespace vga {

using namespace max283x::vga;

constexpr range_t<int8_t> gain_db_range_internal { 0, 63 };

static uint_fast8_t gain_ordinal(const int8_t db) {
	const auto db_sat = gain_db_range_internal.clip(db);
	return (db_sat & 0b111111) ^ 0b111111;
}

} /* namespace vga */

namespace tx {

using namespace max283x::tx;

static uint_fast8_t gain_ordinal(const int8_t db) {
	const auto db_sat = gain_db_range.clip(db);
	return 47 - db_sat;
}

} /* namespace tx */

namespace filter {

using namespace max283x::filter;

static uint_fast8_t bandwidth_ordinal(const uint32_t bandwidth) {
	/* Determine filter setting that will provide bandwidth greater than or
	 * equal to requested bandwidth.
	 */
	return std::lower_bound(bandwidths.cbegin(), bandwidths.cend(), bandwidth) - bandwidths.cbegin();
}

} /* namespace filter */

/* Empirical testing indicates about 25us is necessary to get a valid
 * temperature sense conversion from the ADC.
 */
constexpr float seconds_for_temperature_sense_adc_conversion = 30.0e-6;
constexpr halrtcnt_t ticks_for_temperature_sense_adc_conversion = (base_m4_clk_f * seconds_for_temperature_sense_adc_conversion + 1);

constexpr uint32_t reference_frequency = max283x_reference_f;
constexpr uint32_t pll_factor = 1.0 / (4.0 / 3.0 / reference_frequency) + 0.5;

static int_fast8_t requested_rx_lna_gain = 0;
static int_fast8_t requested_rx_vga_gain = 0;

void MAX2839::init() {
	set_mode(Mode::Shutdown);

	gpio_max283x_enable.output();
	gpio_max2839_rxtx.output();

	_map.r.rxrf_1.MIMOmode = 1;			/* enable RXINB */

	_map.r.pa_drv.TXVGA_GAIN_SPI_EN = 1;
	_map.r.tx_gain.TXVGA_GAIN_SPI = 0x00;

	_map.r.hpfsm_3.HPC_STOP = 1;		/* 1kHz */

	_map.r.rxrf_2.LNAgain_SPI_EN = 1;	/* control LNA gain from SPI */
	_map.r.lpf_vga_1.L = 0b000;
	_map.r.lpf_vga_2.L = 0b000;

	_map.r.rx_top_1.VGAgain_SPI_EN = 1;	/* control VGA gain from SPI */
	_map.r.lpf_vga_1.VGA = 0b000000;
	_map.r.lpf_vga_2.VGA = 0b010101;

	_map.r.lpf_vga_2.BUFF_VCM = 0b11;	/* maximum RX output common-mode voltage */

	_map.r.lpf_vga_1.ModeCtrl = 0b01;	/* Rx LPF */
	_map.r.lpf.FT = 0b0000;				/* 1.75 MHz LPF */

	_map.r.spi_en.EN_SPI = 1;			/* enable chip functions when ENABLE pin set */

	_map.r.lo_gen.LOGEN_2GM = 0;

	_map.r.rssi_vga.RSSI_MODE = 1;		/* RSSI independent of RXHP */

	/*
	 * There are two LNA band settings, but we only use one of them.
	 * Switching to the other one doesn't make the overall spectrum any
	 * flatter but adds a surprise step in the middle.
	 */
	_map.r.rxrf_1.LNAband = 0;			/* 2.3 - 2.5GHz */

	_dirty.set();
	flush();

	set_mode(Mode::Standby);
}

enum class Mask {
	Enable   = 0b01,
	RxTx     = 0b10,
	Shutdown = 0b00,
	Standby  = RxTx,
	Receive  = Enable | RxTx,
	Transmit = Enable,
};

Mask mode_mask(const Mode mode) {
	switch (mode) {
		case Mode::Standby:  return Mask::Standby;
		case Mode::Receive:  return Mask::Receive;
		case Mode::Transmit: return Mask::Transmit;
		default: return Mask::Shutdown;
	}
}

void MAX2839::set_mode(const Mode mode) {
	Mask mask = mode_mask(mode);
	gpio_max283x_enable.write(toUType(mask) & toUType(Mask::Enable));
	gpio_max2839_rxtx.write(toUType(mask) & toUType(Mask::RxTx));
}

void MAX2839::flush() {
	if( _dirty ) {
		for(size_t n=0; n<reg_count; n++) {
			if( _dirty[n] ) {
				write(n, _map.w[n]);
			}
		}
		_dirty.clear();
	}
}

void MAX2839::flush_one(const Register reg) {
	const auto reg_num = toUType(reg);
	write(reg_num, _map.w[reg_num]);
	_dirty.clear(reg_num);
}

void MAX2839::write(const address_t reg_num, const reg_t value) {
	uint16_t t = (0U << 15) | (reg_num << 10) | (value & 0x3ffU);
	_target.transfer(&t, 1);
}

reg_t MAX2839::read(const address_t reg_num) {
	uint16_t t = (1U << 15) | (reg_num << 10);
	_target.transfer(&t, 1U);
	return t & 0x3ffU;
}

void MAX2839::write(const Register reg, const reg_t value) {
	write(toUType(reg), value);
}

reg_t MAX2839::read(const Register reg) {
	return read(toUType(reg));
}

void MAX2839::set_tx_vga_gain(const int_fast8_t db) {
	_map.r.tx_gain.TXVGA_GAIN_SPI = tx::gain_ordinal(db);
	_dirty[Register::TX_GAIN] = 1;
	flush();
}

/*
 * MAX2839 gain rain ranges differ slightly from MAX2837's but are close
 * enough that it makes sense to emulate MAX2837 gain ranges for a consistent
 * user experience.
 */
void MAX2839::configure_rx_gain() {
	/* Apply MAX2837 restrictions to requested gain settings. */
	int_fast8_t lna_gain = lna::gain_db_range.clip(requested_rx_lna_gain);
	lna_gain &= 0x38;
	int_fast8_t vga_gain = vga::gain_db_range.clip(requested_rx_vga_gain);
	vga_gain &= 0x3e;

	/*
	 * MAX2839 has lower full-scale RX output voltage than MAX2837, so we
	 * adjust the VGA (baseband) gain to compensate.
	 */
	vga_gain += 3;

	/*
	 * If that adjustment puts VGA gain out of range, use LNA gain to
	 * compensate.  MAX2839 VGA gain can be any number from 0 through 63.
	 */
	if (vga_gain > 63) {
		if (lna_gain <= 32) {
			vga_gain -= 8;
			lna_gain += 8;
		} else {
			vga_gain = 63;
		}
	}

	/*
	 * MAX2839 lacks max-24 dB (16 dB) and max-40 dB (0 dB) LNA gain
	 * settings, so we use VGA gain to compensate.
	 */
	if (lna_gain == 0) {
		lna_gain = 8;
		vga_gain = (vga_gain >= 8) ? vga_gain - 8 : 0;
	}
	if (lna_gain == 16) {
		if (vga_gain > 32) {
			vga_gain -= 8;
			lna_gain += 8;
		} else {
			vga_gain += 8;
			lna_gain -= 8;
		}
	}

	_map.r.lpf_vga_2.L = lna::gain_ordinal(lna_gain);
	_dirty[Register::RXRF_2] = 1;
	_map.r.lpf_vga_2.VGA = vga::gain_ordinal(vga_gain);
	_dirty[Register::LPF_VGA_2] = 1;
	flush();
}

void MAX2839::set_lna_gain(const int_fast8_t db) {
	requested_rx_lna_gain = db;
	configure_rx_gain();
}

void MAX2839::set_vga_gain(const int_fast8_t db) {
	requested_rx_vga_gain = db;
	configure_rx_gain();
}

void MAX2839::set_lpf_rf_bandwidth(const uint32_t bandwidth_minimum) {
	_map.r.lpf.FT = filter::bandwidth_ordinal(bandwidth_minimum);
	_dirty[Register::LPF] = 1;
	flush();
}

bool MAX2839::set_frequency(const rf::Frequency lo_frequency) {
	/* TODO: This is a sad implementation. Refactor. */
	if( lo::band[0].contains(lo_frequency) ) {
		_map.r.syn_int_div.LOGEN_BSW = 0b00;	/* 2300 - 2399.99MHz */
	} else if( lo::band[1].contains(lo_frequency)  ) {
		_map.r.syn_int_div.LOGEN_BSW = 0b01;	/* 2400 - 2499.99MHz */
	} else if( lo::band[2].contains(lo_frequency) ) {
		_map.r.syn_int_div.LOGEN_BSW = 0b10;	/* 2500 - 2599.99MHz */
	} else if( lo::band[3].contains(lo_frequency) ) {
		_map.r.syn_int_div.LOGEN_BSW = 0b11;	/* 2600 - 2700Hz */
	} else {
		return false;
	}
	_dirty[Register::SYN_INT_DIV] = 1;

	const uint64_t div_q20 = (lo_frequency * (1 << 20)) / pll_factor;

	_map.r.syn_int_div.SYN_INTDIV = div_q20 >> 20;
	_dirty[Register::SYN_INT_DIV] = 1;
	_map.r.syn_fr_div_2.SYN_FRDIV_19_10 = (div_q20 >> 10) & 0x3ff;
	_dirty[Register::SYN_FR_DIV_2] = 1;
	/* flush to commit high FRDIV first, as low FRDIV commits the change */
	flush();

	_map.r.syn_fr_div_1.SYN_FRDIV_9_0 = (div_q20 & 0x3ff);
	_dirty[Register::SYN_FR_DIV_1] = 1;
	flush();

	return true;
}

void MAX2839::set_rx_lo_iq_calibration(const size_t v) {
	_map.r.rxrf_2.RX_IQERR_SPI_EN = 1;
	_dirty[Register::RXRF_2] = 1;
	_map.r.rxrf_1.iqerr_trim = v;
	_dirty[Register::RXRF_1] = 1;
	flush();
}

void MAX2839::set_rx_buff_vcm(const size_t v) {
	_map.r.lpf_vga_2.BUFF_VCM = v;
	_dirty[Register::LPF_VGA_2] = 1;
	flush();
}

reg_t MAX2839::temp_sense() {
	if( !_map.r.rx_top_2.ts_en ) {
		_map.r.rx_top_2.ts_en = 1;
		flush_one(Register::RX_TOP_2);

		chThdSleepMilliseconds(1);
	}

	_map.r.rx_top_2.ts_adc_trigger = 1;
	flush_one(Register::RX_TOP_2);

	halPolledDelay(ticks_for_temperature_sense_adc_conversion);

	/*
	 * Things look very similar to MAX2837, so this probably works, but the
	 * MAX2839 data sheet does not describe the TEMP_SENSE register contents.
	 */
	const auto value = read(Register::TEMP_SENSE);

	_map.r.rx_top_2.ts_adc_trigger = 0;
	flush_one(Register::RX_TOP_2);

	return value;
}

}