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OpenRTX/platform/drivers/tones/toneGenerator_MDx.c

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/***************************************************************************
* Copyright (C) 2020 by Federico Amedeo Izzo IU2NUO, *
* Niccolò Izzo IU2KIN *
* Frederik Saraci IU2NRO *
* Silvano Seva IU2KWO *
* *
* 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 3 of the License, 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; if not, see <http://www.gnu.org/licenses/> *
***************************************************************************/
#include "toneGenerator_MDx.h"
#include <hwconfig.h>
#include <interfaces/gpio.h>
#include <os.h>
/*
* Sine table for PWM-based sinewave generation, containing 256 samples over one
* period of a 64Hz sinewave. This gives a PWM base frequency of 16.384kHz.
*/
uint8_t sineTable[] =
{
128,131,134,137,140,143,146,149,152,155,158,162,165,167,170,173,176,179,182,
185,188,190,193,196,198,201,203,206,208,211,213,215,218,220,222,224,226,228,
230,232,234,235,237,238,240,241,243,244,245,246,248,249,250,250,251,252,253,
253,254,254,254,255,255,255,255,255,255,255,254,254,254,253,253,252,251,250,
250,249,248,246,245,244,243,241,240,238,237,235,234,232,230,228,226,224,222,
220,218,215,213,211,208,206,203,201,198,196,193,190,188,185,182,179,176,173,
170,167,165,162,158,155,152,149,146,143,140,137,134,131,128,124,121,118,115,
112,109,106,103,100,97,93,90,88,85,82,79,76,73,70,67,65,62,59,57,54,52,49,47,
44,42,40,37,35,33,31,29,27,25,23,21,20,18,17,15,14,12,11,10,9,7,6,5,5,4,3,2,
2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,17,18,20,21,23,
25,27,29,31,33,35,37,40,42,44,47,49,52,54,57,59,62,65,67,70,73,76,79,82,85,88,
90,93,97,100,103,106,109,112,115,118,121,124
};
/*
* Correction factor to compensate for the (slight) difference between the exact
* sampling frequency of the sine table and the PWM frequency generated by the
* timer. This difference causes a frequency error in the resulting output of
* both CTCSS and "beep" signals.
* To compensate for this, simply multiply the target frequency by this
* correction factor.
*/
const float freqCorrFactor = 16384.0f/16406.25;
const uint32_t baseSineFreq = 64;
uint32_t toneTableIndex = 0; /* Current sine table index for CTCSS generator */
uint32_t toneTableIncr = 0; /* CTCSS sine table index increment per tick */
uint32_t beepTableIndex = 0; /* Current sine table index for "beep" generator */
uint32_t beepTableIncr = 0; /* "beep" sine table index increment per tick */
uint32_t beepTimerCount = 0; /* Downcounter for timed "beep" */
void __attribute__((used)) TIM3_IRQHandler()
{
OSIntEnter();
toneTableIndex += toneTableIncr;
beepTableIndex += beepTableIncr;
TIM3->CCR2 = sineTable[(toneTableIndex >> 16) & 0xFF];
TIM3->CCR3 = sineTable[(beepTableIndex >> 16) & 0xFF];
TIM3->SR = 0;
if(beepTimerCount > 0)
{
beepTimerCount--;
if(beepTimerCount == 0)
{
TIM3->CCER &= ~TIM_CCER_CC3E;
}
}
/* Shutdown timer if both compare channels are inactive */
if((TIM3->CCER & (TIM_CCER_CC2E | TIM_CCER_CC3E)) == 0)
{
TIM3->CR1 &= ~TIM_CR1_CEN;
}
OSIntExit();
}
void toneGen_init()
{
/*
* Configure GPIOs:
* - CTCSS output is on PC7 (on MD380), that is TIM3-CH2, AF2
* - "beep" output is on PC8 (on MD380), that is TIM3-CH3, AF2
*/
gpio_setMode(CTCSS_OUT, ALTERNATE);
gpio_setMode(BEEP_OUT, ALTERNATE);
gpio_setAlternateFunction(CTCSS_OUT, 2);
gpio_setAlternateFunction(BEEP_OUT, 2);
/*
* Timer configuration:
* - APB1 frequency = 42MHz but timer run at twice of this frequency: with
* 1:20 prescaler we have Ftick = 4.2MHz
* - ARR = 255 (8-bit PWM), gives an update rate of 16.406kHz
* - Nominal update rate is 16.384kHz -> error = +22.25Hz
*/
RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
__DSB();
TIM3->ARR = 0xFF;
TIM3->PSC = 19;
TIM3->CCMR1 = TIM_CCMR1_OC2M_2 /* CH2 in PWM mode 1, preload enabled */
| TIM_CCMR1_OC2M_1
| TIM_CCMR1_OC2PE;
TIM3->CCMR2 = TIM_CCMR2_OC3M_2 /* The same for CH3 */
| TIM_CCMR2_OC3M_1
| TIM_CCMR2_OC3PE;
TIM3->DIER |= TIM_DIER_UIE; /* Interrupt on counter update */
TIM3->CR1 |= TIM_CR1_ARPE; /* Enable auto preload on reload */
NVIC_SetPriority(TIM3_IRQn, 10);
NVIC_EnableIRQ(TIM3_IRQn);
}
void toneGen_terminate()
{
RCC->APB1ENR &= ~RCC_APB1ENR_TIM3EN;
__DSB();
gpio_setMode(CTCSS_OUT, INPUT);
gpio_setMode(BEEP_OUT, INPUT);
}
void toneGen_setToneFreq(float toneFreq)
{
/*
* Convert to 16.16 fixed point number, then divide by the frequency of
* sinewave stored in the PWM table
*/
float dividend = toneFreq * freqCorrFactor * 65536.0f;
toneTableIncr = ((uint32_t) dividend)/baseSineFreq;
}
void toneGen_toneOn()
{
TIM3->CCER |= TIM_CCER_CC2E;
TIM3->CR1 |= TIM_CR1_CEN;
}
void toneGen_toneOff()
{
TIM3->CCER &= ~TIM_CCER_CC2E;
}
void toneGen_setBeepFreq(float beepFreq)
{
float dividend = beepFreq * freqCorrFactor * 65536.0f;
beepTableIncr = ((uint32_t) dividend)/baseSineFreq;
}
void toneGen_beepOn()
{
TIM3->CCER |= TIM_CCER_CC3E;
TIM3->CR1 |= TIM_CR1_CEN;
}
void toneGen_beepOff()
{
TIM3->CCER &= ~TIM_CCER_CC3E;
}
void toneGen_timedBeep(uint16_t duration)
{
/*
* Duration is in milliseconds, while counter update rate is 16.406kHz.
* Thus, the value for downcounter is (duration * 16.406)/1000.
*/
beepTimerCount = (duration * 16406)/1000;
TIM3->CCER |= TIM_CCER_CC3E;
TIM3->CR1 |= TIM_CR1_CEN;
}
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