From 64417f3ab782ec4d25674f44b798d804ada85521 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20Hamal=20Dvo=C5=99=C3=A1k?= <mordae@anilinux.org>
Date: Wed, 24 Jan 2024 23:51:36 +0100
Subject: [PATCH] Avoid randomness in LO and bias for better SNR
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Signed-off-by: Jan Hamal Dvořák <mordae@anilinux.org>
---
src/main.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/src/main.c b/src/main.c
index 16caaf8..303d9e7 100644
--- a/src/main.c
+++ b/src/main.c
@@ -77,7 +77,6 @@ static void bias_init(int in_pin, int out_pin)
gpio_disable_pulls(in_pin);
gpio_disable_pulls(out_pin);
- pio_gpio_init(pio1, in_pin);
pio_gpio_init(pio1, out_pin);
gpio_set_input_hysteresis_enabled(in_pin, false);
@@ -105,7 +104,7 @@ static void bias_init(int in_pin, int out_pin)
sm_config_set_out_pins(&pc, out_pin, 1);
sm_config_set_set_pins(&pc, out_pin, 1);
sm_config_set_wrap(&pc, 0, 0);
- sm_config_set_clkdiv_int_frac(&pc, 1, 127);
+ sm_config_set_clkdiv_int_frac(&pc, 1, 0);
pio_sm_init(pio1, 0, 0, &pc);
pio_sm_set_consecutive_pindirs(pio1, 0, out_pin, 1, GPIO_OUT);
@@ -116,7 +115,6 @@ static void bias_init(int in_pin, int out_pin)
static void watch_init(int in_pin)
{
gpio_disable_pulls(in_pin);
- pio_gpio_init(pio1, in_pin);
gpio_set_input_hysteresis_enabled(in_pin, false);
@@ -270,13 +268,11 @@ static float lo_freq_init(float req_freq)
unsigned bcos = 0;
for (int j = 0; j < 32; j++) {
- int nudge = rand() % step - step / 2;
-
- bcos |= (acos + nudge) >> 31;
+ bcos |= acos >> 31;
bcos <<= 1;
acos += step;
- bsin |= (asin + nudge) >> 31;
+ bsin |= asin >> 31;
bsin <<= 1;
asin += step;
}