Feature for automatic transmission of HAM callsign

Firmware/radio/at.c

@@ -37,6 +37,7 @@
 #include "flash_layout.h"
 #include "at.h"
 #include "board.h"
+#include "ham.h"
 
 #ifdef INCLUDE_AES
 #include "AES/aes.h"
@@ -70,6 +71,7 @@ static void at_m(void);
 
 #pragma save
 #pragma nooverlay
+
 void
 at_input(register uint8_t c)
 {
@@ -458,7 +460,58 @@ at_ampersand(void)
         break;
     }
 #endif // INCLUDE_AES
-	default:
+    case 'C':
+        switch (at_cmd[4]) {
+			case 'E':
+				// enables transmission of callsign (default every 10 minutes)
+				enable_callsign = true;
+				printf("Transmission of callsign enabled: %s\n",callsign);
+				break;
+			case 'D':
+				// disables transmission of callsign
+				enable_callsign = false;
+				printf("Transmission of callsign disabled: %s\n",callsign);
+				break;
+			case 'S':
+				// user is entering their callsign
+				// interval (in seconds) between transmission of callsign
+				// get the register number first
+				if(at_cmd[5] == '=')
+				{
+					register uint8_t c;
+					idx = 6;
+					uint8_t cs_idx = 0;
+					for (;;) {
+						c = at_cmd[idx];
+						// if (!isalnum(c))
+						if (!(isalpha(c) || isdigit(c)))
+							break;
+						callsign[cs_idx++] = c;
+						idx++;
+					}
+					printf("Callsign set to %s\n",callsign);
+				}
+				else
+					at_error();
+				break;
+			case 'I':
+				// interval (in seconds) between transmission of callsign
+				// get the register number first
+				if(at_cmd[5] == '=')
+				{
+					idx = 6;
+					at_parse_number();
+					// Max allowed interval is 10 minutes
+					callsign_tx_interval_secs = at_num < MAX_CALLSIGN_INTERVAL_SEC ? at_num : MAX_CALLSIGN_INTERVAL_SEC;
+					printf("Callsign transmission interval %d s\n",callsign_tx_interval_secs);
+				}
+				else
+					at_error();
+				break;
+        }
+        break;
+
+    default:
 		at_error();
 		break;
 	}

Firmware/radio/ham.c

@@ -0,0 +1,51 @@
+// -*- Mode: C; c-basic-offset: 8; -*-
+//
+// Copyright (c) 2025 Alexis Nicole Benini, Ph.D.
+// www.alexisbenini.com
+// All Rights Reserved
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+//  o Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+//  o Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in
+//    the documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+// OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+
+///
+/// @file	ham.c
+///
+/// Functions for transmission of HAM radio callsign
+///
+
+#include "ham.h"
+#include <string.h>
+
+__xdata char callsign[CALLSIGN_MAX_LENGTH];
+__pdata uint16_t callsign_tx_interval_secs;
+__pdata bool enable_callsign;
+
+#pragma nooverlay
+
+void initialize_ham_callsign_tx_params()
+{
+	enable_callsign = false;
+	memcpy(callsign,"NOSIGN",7);
+	callsign_tx_interval_secs = 2; // 600;
+}

Firmware/radio/ham.h

@@ -0,0 +1,53 @@
+// -*- Mode: C; c-basic-offset: 8; -*-
+//
+// Copyright (c) 2025 Alexis Nicole Benini, Ph.D.
+// www.alexisbenini.com
+// All Rights Reserved
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+//  o Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+//  o Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in
+//    the documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+// OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+
+///
+/// @file	ham.h
+///
+/// Function and parameters for transmission of HAM radio callsign
+///
+
+#ifndef _HAM_H_
+#define _HAM_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "cdt.h"
+
+#define MAX_CALLSIGN_INTERVAL_SEC 10*60       // According to FCC rules, the call sign must be transmitted at least every 10 minutes.
+#define CALLSIGN_MAX_LENGTH 8                 // This includes the initial "DE" sequence
+extern __xdata char callsign[CALLSIGN_MAX_LENGTH];   // This assumes that the operator is using a standard callsign length (6).
+                                              // However, some regions might use 7 characters. The length of this array includes also the \0 at the end
+extern __pdata uint16_t callsign_tx_interval_secs;   // This is set to 600 seconds (10 minutes) by default
+extern __pdata bool enable_callsign;                 // Set to false by default (no callsign transmission)
+
+void initialize_ham_callsign_tx_params();
+
+#endif	// _HAM_H_

Firmware/radio/main.c

@@ -41,6 +41,7 @@
 #include "tdm.h"
 #include "timer.h"
 #include "freq_hopping.h"
+#include "ham.h"
 
 #ifdef INCLUDE_AES
 #include "AES/aes.h"
@@ -129,6 +130,9 @@ main(void)
 	// do radio initialisation
 	radio_init();
 
+	// ham radio callsign initialization
+	initialize_ham_callsign_tx_params();
+
 	// turn on the receiver
 	if (!radio_receiver_on()) {
 		panic("failed to enable receiver");

Firmware/radio/tdm.c

@@ -42,6 +42,7 @@
 #include "freq_hopping.h"
 #include "crc.h"
 #include "serial.h"
+#include "ham.h"
 
 #ifdef INCLUDE_AES
 #include "AES/aes.h"
@@ -139,6 +140,7 @@ static __bit send_statistics;
 /// set when we should send a MAVLink report pkt
 extern uint8_t seen_mavlink;
 
+
 struct tdm_trailer {
 	uint16_t window:13;
 	uint16_t command:1;
@@ -156,6 +158,7 @@ static __pdata char remote_at_cmd[AT_CMD_MAXLEN + 1];
 
 #define PACKET_OVERHEAD (sizeof(trailer)+16)
 
+
 /// display RSSI output
 ///
 void
@@ -495,6 +498,7 @@ handle_at_command(__pdata uint8_t len)
 // a stack carary to detect a stack overflow
 __at(0xFF) uint8_t __idata _canary;
 
+
 /// main loop for time division multiplexing transparent serial
 ///
 void
@@ -516,9 +520,13 @@ tdm_serial_loop(void)
   __pdata uint16_t last_t = timer2_tick();
   __pdata uint16_t last_link_update = last_t;
 
+  __pdata uint16_t half_seconds = 0;
+  __pdata bool tx_callsign = false;
 
   _canary = 42;
 
+  uint8_t counter = 0;
+
   for (;;) {
     if (_canary != 42) {
       panic("stack blown\n");
@@ -627,7 +635,7 @@ tdm_serial_loop(void)
       }
       continue;
     }
-    
+
     // see how many 16usec ticks have passed and update
     // the tdm state machine. We re-fetch tnow as a bad
     // packet could have cost us a lot of time.
@@ -640,8 +648,15 @@ tdm_serial_loop(void)
     if (tnow - last_link_update > 32768) {
       link_update();
       last_link_update = tnow;
+      half_seconds++;
     }
 
+    // enable transmission of callsign
+    if(enable_callsign && half_seconds/2 > callsign_tx_interval_secs)
+    {
+		tx_callsign = true;
+		half_seconds = 0;
+    }
 
     if (lbt_rssi != 0) {
       // implement listen before talk
@@ -738,26 +753,37 @@ tdm_serial_loop(void)
     pins_user_check();
 #endif
 
-    // ask the packet system for the next packet to send
-    if (send_at_command && 
-            max_xmit >= strlen(remote_at_cmd)) {
-      // send a remote AT command
-      len = strlen(remote_at_cmd);
-      memcpy(pbuf, remote_at_cmd, len);
-      trailer.command = 1;
-      send_at_command = false;
-    } else {
-      // get a packet from the serial port
-      len = packet_get_next(max_xmit, pbuf);
-
-      if (len > 0) {
-         trailer.command = packet_is_injected();
-      } else {
-         trailer.command = 0;
-      }
+    if(tx_callsign)
+    {
+        len = 7;
+    	// printf("time to send: %s\n",callsign);
+        memcpy(pbuf,callsign, 7);
+        trailer.command = 1;
+        tx_callsign = false;
+    }
+    else
+    {
+        // ask the packet system for the next packet to send
+        if (send_at_command &&
+                max_xmit >= strlen(remote_at_cmd)) {
+          // send a remote AT command
+          len = strlen(remote_at_cmd);
+          memcpy(pbuf, remote_at_cmd, len);
+          trailer.command = 1;
+          send_at_command = false;
+        } else {
+          // get a packet from the serial port
+    	  len = packet_get_next(max_xmit, pbuf);
+
+    	  if (len > 0) {
+    		 trailer.command = packet_is_injected();
+    	  } else {
+    		 trailer.command = 0;
+    	  }
 #ifdef INCLUDE_AES
-      trailer.crc = crc16(len, pbuf);
+          trailer.crc = crc16(len, pbuf);
 #endif
+        }
     }
 
     if (len > max_data_packet_length) {