From a7362dc14bca1233eb34b41aefebe9cfb22684ac Mon Sep 17 00:00:00 2001
From: "info@mode42.com" <info@mode42.com>
Date: Fri, 7 Aug 2026 18:09:58 +0000
Subject: Initial push

---
 firmware/s1224/src/common/sense.c | 72 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 firmware/s1224/src/common/sense.c

(limited to 'firmware/s1224/src/common/sense.c')

diff --git a/firmware/s1224/src/common/sense.c b/firmware/s1224/src/common/sense.c
new file mode 100644
index 0000000..376004d
--- /dev/null
+++ b/firmware/s1224/src/common/sense.c
@@ -0,0 +1,72 @@
+/*
+ * Sense for softmodem: carrier from demod stub + optional GP7 heuristic.
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+#include "sense.h"
+#include "board_pins.h"
+#include "config.h"
+#include "afsk_soft.h"
+#include "hardware/gpio.h"
+#include "pico/stdlib.h"
+#include <stdint.h>
+
+static bool g_signal;
+static bool g_packet;
+static bool g_flag;
+static absolute_time_t g_packet_until;
+static absolute_time_t g_window_start;
+static uint16_t g_edges;
+static bool g_last_rxd;
+static bool g_hold_valid;
+
+void sense_init(void)
+{
+    g_signal = false;
+    g_packet = false;
+    g_flag = false;
+    g_hold_valid = false;
+    g_window_start = get_absolute_time();
+    g_edges = 0;
+    g_last_rxd = gpio_get(PIN_MODEM_RXD);
+}
+
+void sense_poll(void)
+{
+    const s1224_config_t *cfg = config_get();
+
+    g_signal = afsk_rx_carrier_active();
+
+    bool rxd = gpio_get(PIN_MODEM_RXD);
+    if (rxd != g_last_rxd) {
+        g_edges++;
+        g_last_rxd = rxd;
+    }
+
+    uint32_t win_ms = cfg->packet_window_ms ? cfg->packet_window_ms : 50;
+    if (absolute_time_diff_us(g_window_start, get_absolute_time()) >=
+        (int64_t)win_ms * 1000) {
+        if (g_edges >= cfg->packet_edge_min) {
+            g_packet_until = make_timeout_time_ms(
+                cfg->packet_hold_ms ? cfg->packet_hold_ms : 500);
+            g_hold_valid = true;
+        }
+        g_edges = 0;
+        g_window_start = get_absolute_time();
+    }
+
+    if (g_hold_valid) {
+        if (time_reached(g_packet_until)) {
+            g_hold_valid = false;
+            g_packet = false;
+            g_flag = false;
+        } else {
+            g_packet = true;
+        }
+    } else {
+        g_packet = false;
+    }
+}
+
+bool sense_signal_active(void) { return g_signal; }
+bool sense_packet_active(void) { return g_packet; }
+bool sense_packet_flag(void) { return g_flag; }
-- 
cgit v1.3.1