Modified by ChatGPT for migration to microRecticulum_Firmware, not verified by me... yet, but I am preserving to document this stage.

firmware/fieldtest_beacon/platformio.ini

@@ -15,8 +15,13 @@ monitor_speed = 115200
 ; Pull in microReticulum from your repo tree
 build_flags =
   -I ../../external/microReticulum/src
+  -I ../../external/microReticulum_Firmware
+  -D BOARD_MODEL=BOARD_TBEAM_S_V1
   -D FIELDTEST_BEACON=1
 
 lib_deps =
+  bblanchon/ArduinoJson@~7.4.2
+  hideakitai/MsgPack@~0.4.2
+  rweather/Crypto@^0.4.0
   ; SD stack usually comes with Arduino core
   ; Add your LoRa radio library here (RadioLib, SX126x-Arduino, etc.)

firmware/fieldtest_beacon/src/main.cpp

@@ -6,6 +6,7 @@
 #include <Arduino.h>
 #include <SPI.h>
 #include <SD.h>
+#include "Boards.h"
 
 // Include microReticulum headers from your external tree
 #include "Identity.h"
@@ -24,8 +25,8 @@ static uint32_t g_iter = 0;
 static uint32_t g_next_tx = 0;
 static File g_log;
 
-// TODO: replace with your board’s SD CS pin if not default
-static const int SD_CS_PIN = 10;
+// Source board pin mapping from microReticulum_Firmware board definitions.
+static const int SD_CS_PIN = SD_CS;
 
 // Simple line logger (append-only)
 static void log_line(const String& line) {