Experiment with headphones
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src/cordic.h
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50
src/cordic.h
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#pragma once
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/*
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* Copyright (c) 2020 STMicroelectronics.
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* All rights reserved.
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*
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* This software component is licensed by ST under BSD 3-Clause license,
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* the "License"; You may not use this file except in compliance with the
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* License. You may obtain a copy of the License at:
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*
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* https://opensource.org/licenses/BSD-3-Clause
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*/
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#define CORDIC_MAXITER 9
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#define CORDIC_PI 0x10000000
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static int CORDIC_ZTBL[] = { 0x04000000, 0x025C80A4, 0x013F670B, 0x00A2223B, 0x005161A8, 0x0028BAFC,
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0x00145EC4, 0x000A2F8B, 0x000517CA, 0x00028BE6, 0x000145F3, 0x0000A2FA,
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0x0000517D, 0x000028BE, 0x0000145F, 0x00000A30 };
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inline static __attribute__((__unused__)) int fast_atan2(int y, int x)
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{
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int k, tx, z = 0, fl = 0;
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if (x < 0) {
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fl = ((y > 0) ? +1 : -1);
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x = -x;
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y = -y;
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}
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for (k = 0; k < CORDIC_MAXITER; k++) {
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tx = x;
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if (y <= 0) {
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x -= (y >> k);
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y += (tx >> k);
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z -= CORDIC_ZTBL[k];
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} else {
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x += (y >> k);
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y -= (tx >> k);
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z += CORDIC_ZTBL[k];
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}
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}
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if (fl != 0) {
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z += fl * CORDIC_PI;
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}
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return z;
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}
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114
src/main.c
114
src/main.c
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@ -21,6 +21,8 @@
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#include <limits.h>
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#include <stdlib.h>
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#include "cordic.h"
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#define VREG_VOLTAGE VREG_VOLTAGE_1_20
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#define CLK_SYS_HZ (300 * MHZ)
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#define PSU_PIN 23
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@ -48,6 +50,12 @@ static_assert(RX_STRIDE * 4 < RX_WORDS, "RX_STRIDE * 4 < RX_WORDS");
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static uint32_t rx_cos[RX_WORDS] __attribute__((__aligned__(1 << RX_BITS_DEPTH)));
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static uint32_t rx_sin[RX_WORDS] __attribute__((__aligned__(1 << RX_BITS_DEPTH)));
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#define AOUT_PIN 0
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#define AOUT_BITS_DEPTH 9
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#define AOUT_WORDS (1 << (AOUT_BITS_DEPTH - 1))
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static uint16_t aout_buf[AOUT_WORDS] __attribute__((__aligned__(1 << AOUT_BITS_DEPTH)));
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#define INIT_GAIN 120
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#define INIT_SAMPLE_RATE 100000
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#define INIT_FREQ 94600000
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@ -79,10 +87,16 @@ static int dma_t_samp = -1;
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static int dma_ch_in_cos = -1;
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static int dma_ch_in_sin = -1;
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static int dma_ch_aout = -1;
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static int dma_t_aout = -1;
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static queue_t iq_queue;
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static uint8_t iq_queue_buffer[IQ_QUEUE_LEN][IQ_BLOCK_LEN];
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static int8_t iq_queue_buffer[IQ_QUEUE_LEN][IQ_BLOCK_LEN];
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static size_t iq_queue_pos = 0;
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static int slice, chan;
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static void bias_set_delay(int delay)
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{
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delay += 200;
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@ -290,7 +304,10 @@ static void rf_rx_start(int rx_pin, int bias_pin)
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dma_ch_samp_sin = dma_claim_unused_channel(true);
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dma_ch_samp_trig = dma_claim_unused_channel(true);
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dma_ch_aout = dma_claim_unused_channel(true);
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dma_t_samp = dma_claim_unused_timer(true);
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dma_t_aout = dma_claim_unused_timer(true);
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dma_channel_config dma_conf;
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@ -385,11 +402,24 @@ static void rf_rx_start(int rx_pin, int bias_pin)
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channel_config_set_chain_to(&dma_conf, dma_ch_samp_trig);
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dma_channel_configure(dma_ch_samp_sin, &dma_conf, &pio1->sm[3].instr, samp_insn, 4, false);
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/* Pacing timer for the audio output. */
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dma_timer_set_fraction(dma_t_aout, 1, CLK_SYS_HZ / 200000);
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dma_conf = dma_channel_get_default_config(dma_ch_aout);
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channel_config_set_transfer_data_size(&dma_conf, DMA_SIZE_16);
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channel_config_set_read_increment(&dma_conf, true);
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channel_config_set_write_increment(&dma_conf, false);
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channel_config_set_ring(&dma_conf, false, AOUT_BITS_DEPTH);
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channel_config_set_dreq(&dma_conf, dma_get_timer_dreq(dma_t_aout));
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dma_channel_configure(dma_ch_aout, &dma_conf, &pwm_hw->slice[slice].cc, aout_buf, UINT_MAX,
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false);
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bias_init(rx_pin, bias_pin);
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adder_init();
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dma_channel_start(dma_ch_rx);
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dma_channel_start(dma_ch_samp_trig);
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dma_channel_start(dma_ch_aout);
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watch_init(rx_pin);
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}
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@ -421,6 +451,7 @@ static void rf_rx_stop(void)
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dma_channel_abort(dma_ch_samp_cos);
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dma_channel_abort(dma_ch_samp_sin);
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dma_channel_abort(dma_ch_samp_trig);
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dma_channel_abort(dma_ch_aout);
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dma_channel_cleanup(dma_ch_rx);
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dma_channel_cleanup(dma_ch_cp);
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@ -431,6 +462,7 @@ static void rf_rx_stop(void)
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dma_channel_cleanup(dma_ch_samp_cos);
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dma_channel_cleanup(dma_ch_samp_sin);
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dma_channel_cleanup(dma_ch_samp_trig);
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dma_channel_cleanup(dma_ch_aout);
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dma_channel_unclaim(dma_ch_rx);
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dma_channel_unclaim(dma_ch_cp);
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@ -441,8 +473,10 @@ static void rf_rx_stop(void)
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dma_channel_unclaim(dma_ch_samp_cos);
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dma_channel_unclaim(dma_ch_samp_sin);
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dma_channel_unclaim(dma_ch_samp_trig);
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dma_channel_unclaim(dma_ch_aout);
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dma_timer_unclaim(dma_t_samp);
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dma_timer_unclaim(dma_t_aout);
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dma_ch_rx = -1;
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dma_ch_cp = -1;
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@ -453,8 +487,10 @@ static void rf_rx_stop(void)
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dma_ch_samp_cos = -1;
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dma_ch_samp_sin = -1;
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dma_ch_samp_trig = -1;
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dma_ch_aout = -1;
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dma_t_samp = -1;
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dma_t_aout = -1;
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}
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static void rf_rx(void)
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@ -483,8 +519,8 @@ static void rf_rx(void)
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pos = (pos + RX_STRIDE) & (RX_WORDS - 1);
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uint8_t *block = iq_queue_buffer[iq_queue_pos];
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uint8_t *blockptr = block;
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int8_t *block = iq_queue_buffer[iq_queue_pos];
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int8_t *blockptr = block;
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/*
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* Since every 2 samples add to either +1 or -1,
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@ -551,7 +587,7 @@ static void rf_rx(void)
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else if (I < -128)
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I = -128;
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*blockptr++ = (uint8_t)I + 128;
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*blockptr++ = I;
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Q *= gain;
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Q -= (max_amplitude * 181) / 256;
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@ -562,7 +598,7 @@ static void rf_rx(void)
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else if (Q < -128)
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Q = -128;
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*blockptr++ = (uint8_t)Q + 128;
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*blockptr++ = Q;
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}
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if (queue_try_add(&iq_queue, &block)) {
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@ -649,11 +685,18 @@ static void do_rx(int rx_pin, int bias_pin)
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multicore_launch_core1(rf_rx);
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const uint8_t *block;
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int8_t *block;
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while (queue_try_remove(&iq_queue, &block))
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/* Flush the queue */;
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pwm_set_enabled(slice, true);
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unsigned addr = 0;
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int prev = 0;
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int h0 = 0, h1 = 0, h2 = 0, h3 = 0, h4 = 0, h5 = 0, h6 = 0, h7 = 0;
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int k0 = 0, k1 = 0, k2 = 0, k3 = 0, k4 = 0, k5 = 0, k6 = 0, k7 = 0;
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while (true) {
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int cmd;
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@ -662,12 +705,47 @@ static void do_rx(int rx_pin, int bias_pin)
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goto done;
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if (queue_try_remove(&iq_queue, &block)) {
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fwrite(block, IQ_BLOCK_LEN, 1, stdout);
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fflush(stdout);
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for (int i = 0; i < IQ_BLOCK_LEN; i += 2) {
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while (addr == dma_hw->ch[dma_ch_aout].read_addr)
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sleep_us(1);
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addr += 2;
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if (addr >= (unsigned)aout_buf + AOUT_WORDS * 2)
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addr = (unsigned)aout_buf;
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unsigned pos = addr - (unsigned)aout_buf;
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pos /= 2;
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pos += AOUT_WORDS - 2;
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pos &= AOUT_WORDS - 1;
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//int sample = (127 / M_PI) * atan2f(block[i + 1], block[i]);
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int sample = fast_atan2(block[i + 1], block[i]) / (CORDIC_PI / 128);
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int phase = sample - prev;
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prev = sample;
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uint8_t audio = 128 + (uint8_t)phase;
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h7 = h6, h6 = h5, h5 = h4, h4 = h3, h3 = h2, h2 = h1, h1 = h0,
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h0 = audio;
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audio = (h0 + h1 + h2 + h3 + h4 + h5 + h6 + h7) / 8;
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k7 = k6, k6 = k5, k5 = k4, k4 = k3, k3 = k2, k2 = k1, k1 = k0,
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k0 = audio;
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audio = (k0 + k1 + k2 + k3 + k4 + k5 + k6 + k7) / 8;
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aout_buf[pos] = audio;
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block[i] = audio;
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block[i + 1] = audio;
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}
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//fwrite(block, IQ_BLOCK_LEN, 1, stdout);
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//fflush(stdout);
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}
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}
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done:
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pwm_set_enabled(slice, false);
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multicore_fifo_push_blocking(0);
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multicore_fifo_pop_blocking();
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sleep_us(10);
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@ -693,10 +771,24 @@ int main()
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CLK_SYS_HZ);
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/* Enable PSU PWM mode. */
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gpio_init(PSU_PIN);
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gpio_disable_pulls(PSU_PIN);
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gpio_set_function(PSU_PIN, GPIO_FUNC_SIO);
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gpio_set_dir(PSU_PIN, GPIO_OUT);
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gpio_put(PSU_PIN, 1);
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/* Configure audio output. */
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slice = pwm_gpio_to_slice_num(AOUT_PIN);
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chan = pwm_gpio_to_channel(AOUT_PIN);
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gpio_set_drive_strength(AOUT_PIN, GPIO_DRIVE_STRENGTH_2MA);
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gpio_set_slew_rate(AOUT_PIN, GPIO_SLEW_RATE_SLOW);
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pwm_set_clkdiv_int_frac(slice, 1, 0);
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pwm_set_enabled(slice, false);
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pwm_set_wrap(slice, 2048);
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pwm_set_chan_level(slice, chan, 0);
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gpio_disable_pulls(AOUT_PIN);
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gpio_set_function(AOUT_PIN, GPIO_FUNC_PWM);
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bus_ctrl_hw->priority |= BUSCTRL_BUS_PRIORITY_DMA_W_BITS | BUSCTRL_BUS_PRIORITY_DMA_R_BITS;
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stdio_usb_init();
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@ -706,6 +798,10 @@ int main()
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rx_lo_init(INIT_FREQ - INIT_SAMPLE_RATE, true);
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run_command(0x02, 200000);
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run_command(0x01, 88200000);
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do_rx(10, 11);
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while (true) {
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if (check_command() > 0) {
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static const uint32_t header[3] = { __builtin_bswap32(0x52544c30),
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