mordae/pico-sdr
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Refactor rx_lo_init

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Jan Hamal Dvořák 2024-06-15 12:49:03 +02:00
parent 25c1e608e3
commit 2693c18fdc
1 changed files with 16 additions and 14 deletions
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30
src/main.c
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@ -59,8 +59,8 @@ static int gains[NUM_GAINS] = { 0, 9, 14, 27, 37, 77, 87, 125, 144, 157
static int gain = INIT_GAIN;
static int sample_rate = INIT_SAMPLE_RATE;
#define SIN_PHASE (UINT_MAX / 4)
#define COS_PHASE (0)
#define SIN_PHASE (0u)
#define COS_PHASE (3u << 30)
/* rx -> cp -> cos -> sin -> pio_cos -> pio_sin -> rx ... */
static int dma_ch_rx = -1;
@ -236,33 +236,35 @@ static void adder_init()
pio_sm_set_enabled(pio1, 3, true);
}
static void lo_generate(uint32_t *buf, size_t len, double freq, unsigned phase)
static void lo_generate(uint32_t *buf, double freq, uint32_t phase)
{
static const double base = (UINT_MAX + 1.0) / CLK_SYS_HZ;
unsigned step = base * freq;
unsigned accum = phase;
uint32_t step = base * freq;
for (size_t i = 0; i < len; i++) {
for (size_t i = 0; i < LO_WORDS; i++) {
unsigned bits = 0;
for (int j = 0; j < 32; j++) {
bits |= accum >> 31;
bits |= phase >> 31;
bits <<= 1;
accum += step;
phase += step;
}
buf[i] = bits;
}
}
static void rx_lo_init(double req_freq)
static void rx_lo_init(double req_freq, bool align)
{
const double step_hz = (double)CLK_SYS_HZ / (4 << LO_BITS_DEPTH);
double freq = round(req_freq / step_hz) * step_hz;
double freq = req_freq;
lo_generate(lo_cos, LO_WORDS, freq, COS_PHASE);
lo_generate(lo_sin, LO_WORDS, freq, SIN_PHASE);
if (align)
freq = round(freq / step_hz) * step_hz;
lo_generate(lo_cos, freq, COS_PHASE);
lo_generate(lo_sin, freq, SIN_PHASE);
}
static const uint32_t samp_insn[4] __attribute__((__aligned__(16)));
@ -571,7 +573,7 @@ static void run_command(uint8_t cmd, uint32_t arg)
{
if (0x01 == cmd) {
/* Tune to a new center frequency */
rx_lo_init(arg);
rx_lo_init(arg, true);
} else if (0x02 == cmd) {
/* Set the rate at which IQ sample pairs are sent */
sample_rate = arg;
@ -699,7 +701,7 @@ int main()
queue_init(&iq_queue, sizeof(uint8_t *), IQ_QUEUE_LEN);
rx_lo_init(INIT_FREQ);
rx_lo_init(INIT_FREQ, true);
while (true) {
if (check_command() > 0) {