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Version 1.0 pre-merge release.
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@RPiks
RPiks committed Dec 10, 2023
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16 changes: 8 additions & 8 deletions gpstime/GPStime.c
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Expand Up @@ -11,19 +11,19 @@
//
// DESCRIPTION
//
// GPS time utilities for PioDco oscillator calculates a precise frequency
// GPS time utilities for pico-hf-oscillator calculate a precise frequency
// shift between the local Pico oscillator and reference oscill. of GPS system.
// The value of the shift is used to correct PioDco generated frequency. The
// practical precision of this solution within tenths millihertz range.
// The value of this accuracy depends on quality of navigation solution of GPS
// receiver. This quality can be estimated by GDOP and TDOP parameters received
// The value of the shift is used to correct generated frequency. The practical
// precision of this solution depends on GPS receiver's time pulse stability,
// as well as on quality of navigation solution of GPS receiver.
// This quality can be estimated by GDOP and TDOP parameters received
// in NMEA-0183 message packet from GPS receiver.
// Owing to the meager PioDco frequency step in millihertz range, we obtain
// a quasi-analog precision frequency source (if the GPS navigation works ok).
// Owing to the meager frequency step in millihertz range, we obtain
// a quasi-analog precision frequency source (if the GPS navigation works OK).
// This is an experimental project of amateur radio class and it is devised
// by me on the free will base in order to experiment with QRP narrowband
// digital modes including extremely ones such as QRSS.
// I gracefully appreciate any thoughts or comments on that matter.
// I appreciate any thoughts or comments on that matter.
//
// PLATFORM
// Raspberry Pi pico.
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16 changes: 8 additions & 8 deletions gpstime/GPStime.h
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Expand Up @@ -11,19 +11,19 @@
//
// DESCRIPTION
//
// GPS time utilities for PioDco oscillator calculates a precise frequency
// GPS time utilities for pico-hf-oscillator calculate a precise frequency
// shift between the local Pico oscillator and reference oscill. of GPS system.
// The value of the shift is used to correct PioDco generated frequency. The
// practical precision of this solution within tenths millihertz range.
// The value of this accuracy depends on quality of navigation solution of GPS
// receiver. This quality can be estimated by GDOP and TDOP parameters received
// The value of the shift is used to correct generated frequency. The practical
// precision of this solution depends on GPS receiver's time pulse stability,
// as well as on quality of navigation solution of GPS receiver.
// This quality can be estimated by GDOP and TDOP parameters received
// in NMEA-0183 message packet from GPS receiver.
// Owing to the meager PioDco frequency step in millihertz range, we obtain
// a quasi-analog precision frequency source (if the GPS navigation works ok).
// Owing to the meager frequency step in millihertz range, we obtain
// a quasi-analog precision frequency source (if the GPS navigation works OK).
// This is an experimental project of amateur radio class and it is devised
// by me on the free will base in order to experiment with QRP narrowband
// digital modes including extremely ones such as QRSS.
// I gracefully appreciate any thoughts or comments on that matter.
// I appreciate any thoughts or comments on that matter.
//
// PLATFORM
// Raspberry Pi pico.
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46 changes: 46 additions & 0 deletions lib/utility.h
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@@ -1,3 +1,49 @@
///////////////////////////////////////////////////////////////////////////////
//
// Roman Piksaykin [[email protected]], R2BDY, PhD
// https://www.qrz.com/db/r2bdy
//
///////////////////////////////////////////////////////////////////////////////
//
//
// utility.h - Utilities for RPiks' projects.
//
// DESCRIPTION
// -
//
// PLATFORM
// Raspberry Pi pico.
//
// REVISION HISTORY
//
// Rev 0.1 25 Nov 2023 Initial release
//
// PROJECT PAGE
// https://github.com/RPiks/pico-hf-oscillator
//
// LICENCE
// MIT License (http://www.opensource.org/licenses/mit-license.php)
//
// Copyright (c) 2023 by Roman Piksaykin
//
// Permission is hereby granted, free of charge,to any person obtaining a copy
// of this software and associated documentation files (the Software), to deal
// in the Software without restriction,including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY,WHETHER IN AN ACTION OF CONTRACT,TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
///////////////////////////////////////////////////////////////////////////////
#ifndef UTILITY_H_
#define UTILITY_H_

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66 changes: 28 additions & 38 deletions piodco/dco2.pio
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Expand Up @@ -6,19 +6,43 @@
///////////////////////////////////////////////////////////////////////////////
//
//
// dco2.pio Digital controlled radio freq oscillator based on PIO.
// dco2.pio - Digital controlled radio freq oscillator based on PIO.
//
//
// DESCRIPTION
// -
//
// The oscillator provides precise generation of any frequency ranging
// from 1 Hz to 33.333 MHz with tenth's of millihertz resolution (please note that
// this is relative resolution owing to the fact that the absolute accuracy of
// onboard crystal of pi pico is limited; the absoulte accuracy can be provided
// when using GPS reference option included).
// The DCO uses phase locked loop principle programmed in C and PIO asm.
// The DCO does *NOT* use any floating point operations - all time-critical
// instructions run in 1 CPU cycle.
// Currently the upper freq. limit is about 33.333 MHz and it is achieved only
// using pi pico overclocking to 270 MHz.
// Owing to the meager frequency step, it is possible to use 3, 5, or 7th
// harmonics of generated frequency. Such solution completely cover all HF and
// a portion of VHF band up to about 233 MHz.
// Unfortunately due to pure digital freq.synthesis principle the jitter may
// be a problem on higher frequencies. You should assess the quality of generated
// signal if you want to emit a noticeable power.
// This is an experimental project of amateur radio class and it is devised
// by me on the free will base in order to experiment with QRP narrowband
// digital modes.
// I appreciate any thoughts or comments on that matter.
//
// PLATFORM
// Raspberry Pi pico.
//
// REVISION HISTORY
//
// Rev 2.0 09 Dec 2023
// New algo devising.
// Rev 0.1 05 Nov 2023 Initial release
// Rev 0.2 18 Nov 2023
// Rev 1.0 10 Dec 2023 Improved frequency range (to ~33.333 MHz).
//
// PROJECT PAGE
// https://github.com/RPiks/pico-hf-oscillator
//
// LICENCE
// MIT License (http://www.opensource.org/licenses/mit-license.php)
Expand Down Expand Up @@ -68,40 +92,6 @@ LOOP3:
set pins, 0
.wrap

/*
// it is OK for ~20.5M
.wrap_target
out y, 32
mov x, y
LOOP0:
jmp x-- LOOP0
set pins, 1

mov x, y [1]
LOOP1:
jmp x-- LOOP1
set pins, 0
.wrap
*/
/*
.wrap_target
// CYCLES COUNT
out y, 8 // 1.
LOOP0:
jmp y-- LOOP0 // 2 + y0.
set pins, 1 // 1 * PI 3 + y0.

out y, 8 // 4 + y0.
LOOP1:
jmp y-- LOOP1 // 5 + y0 + y1.
set pins, 0 // 2 * PI 6 + y0 + y1.
// 6 cycles min.=> 270MHz / 6 = 45MHz (VHF low-band).
// 3rd harmonic is 135M.
// 5th is 225M.
// 7th is 315M.
.wrap
*/

% c-sdk {

#define PIOASM_DELAY_CYCLES 4
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50 changes: 22 additions & 28 deletions piodco/piodco.c
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Expand Up @@ -12,21 +12,25 @@
// DESCRIPTION
//
// The oscillator provides precise generation of any frequency ranging
// from 1.1 to 9.4 MHz with tenth's of millihertz resolution (please note that
// from 1 Hz to 33.333 MHz with tenth's of millihertz resolution (please note that
// this is relative resolution owing to the fact that the absolute accuracy of
// onboard crystal of pi pico is limited).
// The DCO uses phase locked loop principle programmed in C.
// onboard crystal of pi pico is limited; the absoulte accuracy can be provided
// when using GPS reference option included).
// The DCO uses phase locked loop principle programmed in C and PIO asm.
// The DCO does *NOT* use any floating point operations - all time-critical
// instructions run in 1 CPU cycle.
// Currently the upper freq. limit is about 9.8 MHz and it is achieved only
// using pi pico overclocking to 270MHz.
// Currently the upper freq. limit is about 33.333 MHz and it is achieved only
// using pi pico overclocking to 270 MHz.
// Owing to the meager frequency step, it is possible to use 3, 5, or 7th
// harmonics of generated frequency. Such solution completely cover all HF and
// low band up to about 66 MHz.
// a portion of VHF band up to about 233 MHz.
// Unfortunately due to pure digital freq.synthesis principle the jitter may
// be a problem on higher frequencies. You should assess the quality of generated
// signal if you want to emit a noticeable power.
// This is an experimental project of amateur radio class and it is devised
// by me on the free will base in order to experiment with QRP narrowband
// digital modes.
// I gracefully appreciate any thoughts or comments on that matter.
// I appreciate any thoughts or comments on that matter.
//
// PLATFORM
// Raspberry Pi pico.
Expand All @@ -35,6 +39,7 @@
//
// Rev 0.1 05 Nov 2023 Initial release
// Rev 0.2 18 Nov 2023
// Rev 1.0 10 Dec 2023 Improved frequency range (to ~33.333 MHz).
//
// PROJECT PAGE
// https://github.com/RPiks/pico-hf-oscillator
Expand Down Expand Up @@ -69,7 +74,7 @@

#include "build/dco2.pio.h"

int32_t si32precise_cycles; /* External in order to support ISR. */
volatile int32_t si32precise_cycles;

/// @brief Initializes DCO context and prepares PIO hardware.
/// @param pdco Ptr to DCO context.
Expand Down Expand Up @@ -121,7 +126,7 @@ int PioDCOSetFreq(PioDco *pdco, uint32_t ui32_frq_hz, int32_t ui32_frq_millihz)
pdco->_frq_cycles_per_pi = (int32_t)(((int64_t)pdco->_clkfreq_hz * (int64_t)(1<<24) * 1000LL
+(i64denominator>>1)) / i64denominator);

si32precise_cycles = pdco->_frq_cycles_per_pi;
si32precise_cycles = pdco->_frq_cycles_per_pi - (PIOASM_DELAY_CYCLES<<24);

return 0;
}
Expand Down Expand Up @@ -174,33 +179,22 @@ void PioDCOStop(PioDco *pdco)
pio_sm_set_enabled(pdco->_pio, pdco->_ism, false);
}

/// @brief Main worker task of DCO V.2. It is time critical, so it ought to be run on
/// @brief the dedicated pi pico core.
/// @param pDCO Ptr to DCO context.
/// @return No return. It spins forever.
void RAM (PioDCOWorker2)(PioDco *pDCO)
{
register PIO pio = pDCO->_pio;
register uint sm = pDCO->_ism;
register int32_t i32acc_error = 0;
const int32_t ui32_frq_hz = 30455133;
const int64_t i64denominator = 2000LL * (int64_t)ui32_frq_hz;
pDCO->_frq_cycles_per_pi = (int32_t)(((int64_t)pDCO->_clkfreq_hz * (int64_t)(1<<24) * 1000LL
+(i64denominator>>1)) / i64denominator);
const register uint32_t i32reg = pDCO->_frq_cycles_per_pi - (4<<24);
register uint32_t i32wc, i32reg;

register uint32_t i32wc;
//const register uint32_t i23left = 8388608U;
LOOP:

i32wc = i32reg;
i32wc -= i32acc_error;
//i32wc += i23left;
i32wc >>= 24U;
i32reg = si32precise_cycles;
i32wc = (i32reg - i32acc_error) >> 24U;
pio_sm_put_blocking(pio, sm, i32wc);
i32wc <<= 24U;
i32acc_error += i32wc - i32reg;

//const int32_t i32wc2 = iSAR32(i32reg - i32acc_error + (1<<23), 24);
//i32acc_error += (i32wc2<<24) - i32reg;

//pio_sm_put_blocking(pio, sm, i32wc - 4);
i32acc_error += (i32wc << 24U) - i32reg;

goto LOOP;
}
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19 changes: 12 additions & 7 deletions piodco/piodco.h
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Original file line number Diff line number Diff line change
Expand Up @@ -12,21 +12,25 @@
// DESCRIPTION
//
// The oscillator provides precise generation of any frequency ranging
// from 1.1 to 9.4 MHz with tenth's of millihertz resolution (please note that
// from 1 Hz to 33.333 MHz with tenth's of millihertz resolution (please note that
// this is relative resolution owing to the fact that the absolute accuracy of
// onboard crystal of pi pico is limited).
// The DCO uses phase locked loop principle programmed in C.
// onboard crystal of pi pico is limited; the absoulte accuracy can be provided
// when using GPS reference option included).
// The DCO uses phase locked loop principle programmed in C and PIO asm.
// The DCO does *NOT* use any floating point operations - all time-critical
// instructions run in 1 CPU cycle.
// Currently the upper freq. limit is about 9.8 MHz and it is achieved only
// using pi pico overclocking to 270MHz.
// Currently the upper freq. limit is about 33.333 MHz and it is achieved only
// using pi pico overclocking to 270 MHz.
// Owing to the meager frequency step, it is possible to use 3, 5, or 7th
// harmonics of generated frequency. Such solution completely cover all HF and
// low band up to about 66 MHz.
// a portion of VHF band up to about 233 MHz.
// Unfortunately due to pure digital freq.synthesis principle the jitter may
// be a problem on higher frequencies. You should assess the quality of generated
// signal if you want to emit a noticeable power.
// This is an experimental project of amateur radio class and it is devised
// by me on the free will base in order to experiment with QRP narrowband
// digital modes.
// I gracefully appreciate any thoughts or comments on that matter.
// I appreciate any thoughts or comments on that matter.
//
// PLATFORM
// Raspberry Pi pico.
Expand All @@ -35,6 +39,7 @@
//
// Rev 0.1 05 Nov 2023 Initial release
// Rev 0.2 18 Nov 2023
// Rev 1.0 10 Dec 2023 Improved frequency range (to ~33.333 MHz).
//
// PROJECT PAGE
// https://github.com/RPiks/pico-hf-oscillator
Expand Down
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