mayhem-firmware/firmware/application/hw/rffc507x.cpp

/*
 * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
 *
 * 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 "rffc507x.hpp"

#include <array>

#include "utility.hpp"

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

#include "hal.h"

#ifdef PRALINE
// Global debug tracking - visible to other files
struct rffc507x_debug_t {
    uint32_t requested_freq_mhz;
    uint32_t calculated_vco_mhz;
    uint32_t expected_n;
    uint8_t expected_lodiv;
    uint8_t expected_presc;
    bool was_called;
    uint32_t calc_lo_freq_mhz;     // Input to calculate()
    uint32_t calc_vco_inside_mhz;  // VCO calculated inside calculate()
    uint8_t calc_lodiv_log2;       // LO divider log2
    uint8_t calc_presc_log2;       // Prescaler log2
    uint64_t calc_n_q24;           // N in Q24 format before shift
};
rffc507x_debug_t rffc507x_debug_info = {0, 0, 0, 0, 0, false, 0, 0, 0, 0, 0};
#endif

namespace rffc507x {

/* Empirical tests indicate no minimum reset pulse width, but the speed
 * of the processor and GPIO probably produce at least 20ns pulse width.
 */
constexpr float seconds_during_reset = 1.0e-6;
constexpr halrtcnt_t ticks_during_reset = (base_m4_clk_f * seconds_during_reset + 1);

/* Empirical testing indicates >3.5us delay required after reset, before
 * registers can be reliably written. Make it 5us, just for fun. Tests were
 * conducted at high temperatures (with a hair dryer) increased room
 * temperature minimum delay of 2.9us to the requirement above.
 */
constexpr float seconds_after_reset = 5.0e-6;
constexpr halrtcnt_t ticks_after_reset = (base_m4_clk_f * seconds_after_reset + 1);

constexpr auto reference_frequency = rffc5072_reference_f;

namespace vco {

constexpr rf::FrequencyRange range{2700000000, 5400000000};

} /* namespace vco */

namespace lo {

constexpr size_t divider_log2_min = 0;
constexpr size_t divider_log2_max = 5;

constexpr size_t divider_min = 1U << divider_log2_min;
constexpr size_t divider_max = 1U << divider_log2_max;

constexpr rf::FrequencyRange range{vco::range.minimum / divider_max, vco::range.maximum / divider_min};

size_t divider_log2(const rf::Frequency lo_frequency) {
    /* TODO: Error */
    /*
        if( lo::range.out_of_range(lo_frequency) ) {
                return;
        }
        */
    /* Compute LO divider. */
    auto lo_divider_log2 = lo::divider_log2_min;
    auto vco_frequency = lo_frequency;
    while (vco::range.below_range(vco_frequency)) {
        vco_frequency <<= 1;
        lo_divider_log2 += 1;
    }

    return lo_divider_log2;
}

} /* namespace lo */

namespace prescaler {

constexpr rf::Frequency max_frequency = 1600000000U;

constexpr size_t divider_log2_min = 1;
constexpr size_t divider_log2_max = 2;

constexpr size_t divider_min = 1U << divider_log2_min;
constexpr size_t divider_max = 1U << divider_log2_max;

constexpr size_t divider_log2(const rf::Frequency vco_frequency) {
#ifdef PRALINE
    // PRALINE FIX: Avoid N register overflow (9-bit max = 511)
    // With 40 MHz reference:
    // - For VCO=5400 MHz, presc=÷2: N = (5400×2)/40 = 270 ✓
    // - For VCO=5400 MHz, presc=÷4: N = (5400×4)/40 = 540 ✗ OVERFLOW!
    //
    // Maximum safe VCO for ÷4 prescaler:
    // N_max = 511, so VCO_max = (511 × 40) / 4 = 5110 MHz
    //
    // Use ÷4 only if VCO < 5110 MHz AND VCO > 3200 MHz
    // Use ÷2 for VCO >= 5110 MHz to avoid overflow

    constexpr rf::Frequency overflow_threshold = 5110000000ULL;  // Max VCO for ÷4
    constexpr rf::Frequency min_presc4_freq = 3200000000ULL;     // Min VCO for ÷4

    if ((vco_frequency > min_presc4_freq) && (vco_frequency < overflow_threshold)) {
        return divider_log2_max;  // ÷4 prescaler
    } else {
        return divider_log2_min;  // ÷2 prescaler
    }
#else
    return (vco_frequency > (prescaler::divider_min * prescaler::max_frequency))
               ? prescaler::divider_log2_max
               : prescaler::divider_log2_min;
#endif
}

} /* namespace prescaler */

struct SynthConfig {
    const size_t lo_divider_log2;
    const size_t prescaler_divider_log2;
    const uint64_t n_divider_q24;

    static SynthConfig calculate(
        const rf::Frequency lo_frequency) {
        /* RFFC507x frequency synthesizer is is accurate to about 2ppb (two parts
         * per BILLION). There's not much point to worrying about rounding and
         * tuning error, when it amounts to 8Hz at 5GHz!
         */
        const size_t lo_divider_log2 = lo::divider_log2(lo_frequency);
        const size_t lo_divider = 1U << lo_divider_log2;

        const rf::Frequency vco_frequency = lo_frequency * lo_divider;

        const size_t prescaler_divider_log2 = prescaler::divider_log2(vco_frequency);

#ifndef PRALINE
        const uint64_t prescaled_lo_q24 = vco_frequency << (24 - prescaler_divider_log2);
#else
        const uint64_t prescaled_lo_q24 = vco_frequency << (24 + prescaler_divider_log2);
#endif
        const uint64_t n_divider_q24 = prescaled_lo_q24 / reference_frequency;

#ifdef PRALINE
        // DEBUG: Track everything
        rffc507x_debug_info.calc_lo_freq_mhz = lo_frequency / 1000000;
        rffc507x_debug_info.calc_vco_inside_mhz = vco_frequency / 1000000;
        rffc507x_debug_info.calc_lodiv_log2 = lo_divider_log2;
        rffc507x_debug_info.calc_presc_log2 = prescaler_divider_log2;
        rffc507x_debug_info.calc_n_q24 = n_divider_q24;
#endif

        return {
            lo_divider_log2,
            prescaler_divider_log2,
            n_divider_q24,
        };
    }
};

/* Readback values, RFFC5072 rev A:
 * 0000: 0x8a01 => dev_id=1000101000000 mrev_id=001
 * 0001: 0x3f7c => lock=0 ct_cal=0111111 cp_cal=011111 ctfail=0 0
 * 0010: 0x806f => v0_cal=10000000 v1_cal=01101111
 * 0011: 0x0000 => rsm_state=00000 f_errflag=00
 * 0100: 0x0000 => vco_count_l=0
 * 0101: 0x0000 => vco_count_h=0
 * 0110: 0xc000 => cal_fbi=1 cal_fbq=1
 * 0111: 0x0000 => vco_sel=0 vco_tc_curve=0
 */

void RFFC507x::init() {
    gpio_rffc5072_resetx.set();
    gpio_rffc5072_resetx.output();
    reset();

    _bus.init();

    _dirty.set();
    flush();
}

void RFFC507x::reset() {
    /* TODO: Is RESETB pin ignored if sdi_ctrl.sipin=1? Programming guide
     * description of sdi_ctrl.sipin suggests the pin is not ignored.
     */
    gpio_rffc5072_resetx.clear();
    halPolledDelay(ticks_during_reset);
    gpio_rffc5072_resetx.set();
    halPolledDelay(ticks_after_reset);
}

void RFFC507x::flush() {
    if (_dirty) {
        for (size_t i = 0; i < _map.w.size(); i++) {
            if (_dirty[i]) {
                write(i, _map.w[i]);
            }
        }
        _dirty.clear();
    }
}

void RFFC507x::write(const address_t reg_num, const spi::reg_t value) {
    _bus.write(reg_num, value);
}

spi::reg_t RFFC507x::read(const address_t reg_num) {
    return _bus.read(reg_num);
}

void RFFC507x::write(const Register reg, const spi::reg_t value) {
    write(toUType(reg), value);
}

spi::reg_t RFFC507x::read(const Register reg) {
    return read(toUType(reg));
}

void RFFC507x::flush_one(const Register reg) {
    const auto reg_num = toUType(reg);
    write(reg_num, _map.w[reg_num]);
    _dirty.clear(reg_num);
}

void RFFC507x::enable() {
    _map.r.sdi_ctrl.enbl = 1;
    flush_one(Register::SDI_CTRL);

    /* TODO: Reset PLLCPL after CT_CAL? */

    /* TODO: After device is enabled and CT_cal is complete and VCO > 3.2GHz,
     * change prescaler divider to 2, update synthesizer ratio, change
     * lf.pllcpl from 3 to 2.
     */
}

void RFFC507x::disable() {
    _map.r.sdi_ctrl.enbl = 0;
    flush_one(Register::SDI_CTRL);
}

void RFFC507x::set_mixer_current(const uint8_t value) {
    /* MIX IDD = 0b000 appears to turn the mixer completely off */
    /* TODO: Adjust mixer current. Graphs in datasheet suggest:
     * MIX_IDD=1 has lowest noise figure (10.1dB vs 13dB @ MIX_IDD=7).
     * MIX_IDD=5 has highest IP3 (24dBm vs 10.3dBm @ MIX_IDD=1).
     * MIX_IDD=5 has highest P1dB (11.8dBm vs 1.5dBm @ MIX_IDD=1).
     * Mixer input impedance ~85 Ohms at MIX_IDD=4.
     * Mixer input impedance inversely proportional to MIX_IDD.
     * Balun balanced (mixer) side is 100 Ohms. Perhaps reduce MIX_IDD
     * a bit to get 100 Ohms from mixer.
     */
    _map.r.mix_cont.p1mixidd = value;
    _map.r.mix_cont.p2mixidd = value;
    flush_one(Register::MIX_CONT);
}

void RFFC507x::set_frequency(const rf::Frequency lo_frequency) {
    const SynthConfig synth_config = SynthConfig::calculate(lo_frequency);

#ifdef PRALINE
    // Calculate VCO frequency from LO frequency and divider
    const size_t lo_divider = 1U << synth_config.lo_divider_log2;  // 2^lodiv_log2
    const rf::Frequency vco_freq = lo_frequency * lo_divider;

    // Track what we calculated
    rffc507x_debug_info.requested_freq_mhz = lo_frequency / 1000000;
    rffc507x_debug_info.calculated_vco_mhz = vco_freq / 1000000;
    rffc507x_debug_info.expected_n = synth_config.n_divider_q24 >> 24;
    rffc507x_debug_info.expected_lodiv = synth_config.lo_divider_log2;
    rffc507x_debug_info.expected_presc = synth_config.prescaler_divider_log2;
    rffc507x_debug_info.was_called = true;
#endif

    /* Boost charge pump leakage if VCO frequency > 3.2GHz, indicated by
     * prescaler divider set to 4 (log2=2) instead of 2 (log2=1).
     */
    if (synth_config.prescaler_divider_log2 == 2) {
        _map.r.lf.pllcpl = 3;
    } else {
        _map.r.lf.pllcpl = 2;
    }
    flush_one(Register::LF);

    _map.r.p2_freq1.p2n = synth_config.n_divider_q24 >> 24;
    _map.r.p2_freq1.p2lodiv = synth_config.lo_divider_log2;
    _map.r.p2_freq1.p2presc = synth_config.prescaler_divider_log2;
    _map.r.p2_freq2.p2nmsb = (synth_config.n_divider_q24 >> 8) & 0xffff;
    _map.r.p2_freq3.p2nlsb = synth_config.n_divider_q24 & 0xff;
    _dirty[Register::P2_FREQ1] = 1;
    _dirty[Register::P2_FREQ2] = 1;
    _dirty[Register::P2_FREQ3] = 1;
    flush();
}

void RFFC507x::set_gpo1(const bool new_value) {
    if (new_value) {
        _map.r.gpo.p2gpo |= 1;
        _map.r.gpo.p1gpo |= 1;
    } else {
        _map.r.gpo.p2gpo &= ~1;
        _map.r.gpo.p1gpo &= ~1;
    }

    flush_one(Register::GPO);
}

spi::reg_t RFFC507x::readback(const Readback readback) {
    /* TODO: This clobbers the rest of the DEV_CTRL register
     * Time to implement bitfields for registers.
     */
    _map.r.dev_ctrl.readsel = toUType(readback);
    flush_one(Register::DEV_CTRL);

    return read(Register::READBACK);
}

} /* namespace rffc507x */