diff --git a/tracker/software/Makefile b/tracker/software/Makefile
index 30a4bc69..6a0aa1be 100644
--- a/tracker/software/Makefile
+++ b/tracker/software/Makefile
@@ -257,7 +257,7 @@ CPPWARN = -Wall -Wextra -Wundef
 #
 
 # List all user C define here, like -D_DEBUG=1
-UDEFS = -D_GNU_SOURCE -DARM_MATH_CM4 -DSHELL_CMD_TEST_ENABLED=0
+UDEFS = -D_GNU_SOURCE -DARM_MATH_CM4 -DSHELL_CMD_TEST_ENABLED=1
 
 # Define ASM defines here
 UADEFS =
diff --git a/tracker/software/pkt/devices/si446x.c b/tracker/software/pkt/devices/si446x.c
index 496c7cae..a1cea64e 100644
--- a/tracker/software/pkt/devices/si446x.c
+++ b/tracker/software/pkt/devices/si446x.c
@@ -1059,16 +1059,6 @@ THD_FUNCTION(si_fifo_feeder_afsk, arg)
           c += more;
           chThdSleep(TIME_MS2I(15));
       }
-
-      /*
-       * Shutdown radio if reception has been interrupted. If reception was interrupted rx_frequency is set.
-       * If reception has not been interrupted rx_frequency is set 0.
-       */
-      if(!rx_frequency) {
-          Si446x_shutdown();
-      } else {
-          Si4464_restoreRX();
-      }
     } else {
       /* Transmit start failed. */
 #ifdef PKT_IS_TEST_PROJECT
@@ -1077,6 +1067,15 @@ THD_FUNCTION(si_fifo_feeder_afsk, arg)
           TRACE_ERROR("SI   > Transmit failed");
 #endif
     }
+    /*
+     * Shutdown radio if reception has been interrupted. If reception was interrupted rx_frequency is set.
+     * If reception has not been interrupted rx_frequency is set 0.
+     */
+    if(!rx_frequency) {
+        Si446x_shutdown();
+    } else {
+        Si4464_restoreRX();
+    }
     // Free packet object memory
     ax25_delete(pp);
     chThdExit(MSG_OK);
diff --git a/tracker/software/pkt/devices/si446x.h b/tracker/software/pkt/devices/si446x.h
index 327c5676..6b57d4b3 100644
--- a/tracker/software/pkt/devices/si446x.h
+++ b/tracker/software/pkt/devices/si446x.h
@@ -37,10 +37,23 @@
 #define Si446x_STATE_TX             7
 #define Si446x_STATE_RX             8
 
-// Si4464 Registers
+/*
+ * Commands.
+ */
 
 #define Si446x_READ_CMD_BUFF                      0x44
+#define Si446x_START_TX                           0x31
+#define Si446x_START_RX                           0x32
+#define Si446x_RX_HOP                             0x36
+
+/* Defined response values. */
+
 #define Si446x_COMMAND_CTS                        0xFF
+
+/*
+ * Property group commands.
+ * Format is 0xGGNN (GG = group, NN = number).
+ */
 #define Si446x_GLOBAL_XO_TUNE                   0x0000
 #define Si446x_GLOBAL_CLK_CFG                   0x0001
 #define Si446x_GLOBAL_CONFIG                    0x0003
diff --git a/tracker/software/pkt/pktconf.h b/tracker/software/pkt/pktconf.h
index 39292a47..b79d1e3d 100644
--- a/tracker/software/pkt/pktconf.h
+++ b/tracker/software/pkt/pktconf.h
@@ -115,6 +115,7 @@
 
 /*
  * Diagnostic output definitions.
+ * TODO: Deprecate.
  *
  */
 
@@ -161,11 +162,22 @@ extern "C" {
 /* Module inline functions.                                                  */
 /*===========================================================================*/
 
+/**
+* @brief   Define GPIO port where the NIRQ from the radio is connected.
+* @notes   The NIRQ line is set in the radio to output the CCA condition.
+*
+* @api
+*/
 static inline void pktSetLineModeCCA(void) {
   palSetLineMode(LINE_CCA, PAL_MODE_INPUT_PULLUP);
 }
 
-/* Decoder blinker LED. */
+/**
+ * @brief   For driving an indicator LED for decoder status.
+ * @notes   These functions control the LED on a GPIO line if defined.
+ *
+ * @api
+ */
 static inline void pktSetLineModeDecoderLED(void) {
 #if defined(LINE_DECODER_LED)
   palSetLineMode(LINE_DECODER_LED, PAL_MODE_OUTPUT_PUSHPULL);
@@ -189,7 +201,12 @@ static inline void pktWriteDecoderLED(uint8_t state) {
 #endif
 }
 
-/* Squelch (CCA) indicator. */
+/**
+ * @brief   For driving an indicator LED for PWM CCA asserted.
+ * @notes   These functions control the LED on a GPIO line if defined.
+ *
+ * @api
+ */
 static inline void pktSetLineModeSquelchLED(void) {
 #if defined(LINE_SQUELCH_LED)
   palSetLineMode(LINE_SQUELCH_LED, PAL_MODE_OUTPUT_PUSHPULL);
@@ -213,7 +230,12 @@ static inline void pktUnsetLineModeSquelchLED(void) {
 #endif
 }
 
-/* Overflow in FIFO queue space. */
+/**
+ * @brief   For driving an indicator LED for PWM queue space exhausted.
+ * @notes   These functions control the LED on a GPIO line if defined.
+ *
+ * @api
+ */
 static inline void pktSetLineModeOverflowLED(void) {
 #if defined(LINE_OVERFLOW_LED)
   palSetLineMode(LINE_OVERFLOW_LED, PAL_MODE_OUTPUT_PUSHPULL);
@@ -237,7 +259,12 @@ static inline void pktUnsetLineModeOverflowLED(void) {
 #endif
 }
 
-/* LED for FIFO out at PWM/ICU side. */
+/**
+ * @brief   For driving an indicator LED for PWM buffers exhausted.
+ * @notes   These functions control the LED on a GPIO line if defined.
+ *
+ * @api
+ */
 static inline void pktSetLineModeNoFIFOLED(void) {
 #if defined(LINE_NO_FIFO_LED)
   palSetLineMode(LINE_NO_FIFO_LED, PAL_MODE_OUTPUT_PUSHPULL);
@@ -261,7 +288,12 @@ static inline void pktUnsetLineModeNoFIFOLED(void) {
 #endif
 }
 
-/* PWM mirroring to a GPIO for diagnostics. */
+/**
+ * @brief   For diagnostics only.
+ * @notes   These functions control the mirroring of radio PWM data to a GPIO.
+ *
+ * @notapi
+ */
 static inline void pktSetLineModePWMMirror(void) {
 #if defined(LINE_PWM_MIRROR)
   palSetLineMode(LINE_PWM_MIRROR, PAL_MODE_OUTPUT_PUSHPULL);
@@ -285,46 +317,15 @@ static inline void pktWritePWMMirror(uint8_t state) {
 #endif
 }
 
-/* Radio configuration for SPI connected radio. */
-/*static inline msg_t pktOpenRadio(packet_svc_t *handler) {
-#if USE_SPI_ATTACHED_RADIO == TRUE
-  msg_t msg = pktSubmitRadioTask(handler, TIME_S2I(10), NULL);
-  return msg;
-#else
-  (void)handler;
-  return MSG_OK;
-#endif
-}*/
-
-/*static inline msg_t pktStartRadio(packet_svc_t *handler) {
-#if USE_SPI_ATTACHED_RADIO == TRUE
-  msg_t msg = pktSubmitRadioTask(handler, TIME_MS2I(100), NULL);
-  return msg;
-#else
-  (void)handler;
-  return MSG_OK;
-#endif
-}*/
-
-/*static inline void pktStopRadio(packet_svc_t *handler) {
-#if USE_SPI_ATTACHED_RADIO == TRUE
-  (void)handler;
-#else
-  (void)handler;
-#endif
-}*/
-
-/*static inline msg_t pktCloseRadio(packet_svc_t *handler) {
-#if USE_SPI_ATTACHED_RADIO == TRUE
-  (void)handler;
-  //Si446x_shutdown();
-#else
-  (void)handler;
-#endif
-  return MSG_OK;
-}*/
-
-
+/**
+ * @brief   Sends a command request to a radio.
+ * @post    The command object posted to the radio manager queue.
+ *
+ * @param[in]   handler     pointer to a @p packet handler object
+ * @param[in]   task        pointer to a task object.
+ *
+ * @api
+ */
 static inline msg_t pktSendRadioCommand(packet_svc_t *handler,
                                         radio_task_object_t *task) {
 #if USE_SPI_ATTACHED_RADIO == TRUE
diff --git a/tracker/software/pkt/protocols/rxax25.h b/tracker/software/pkt/protocols/rxax25.h
index b7b5fcf4..48bd1dc2 100644
--- a/tracker/software/pkt/protocols/rxax25.h
+++ b/tracker/software/pkt/protocols/rxax25.h
@@ -94,6 +94,7 @@ typedef uint8_t ax25char_t;
 typedef int16_t ax25size_t;
 
 #ifdef PKT_IS_TEST_PROJECT
+
 /* TODO: Create a chFactory FIFO to manage these objects. */
 struct packet_s {