diff --git a/libraries/AP_Param/AP_Param.cpp b/libraries/AP_Param/AP_Param.cpp
index a2c471669c..1d1d5e207f 100644
--- a/libraries/AP_Param/AP_Param.cpp
+++ b/libraries/AP_Param/AP_Param.cpp
@@ -68,6 +68,18 @@ const AP_Param::Info *AP_Param::_var_info;
 struct AP_Param::param_override *AP_Param::param_overrides = nullptr;
 uint16_t AP_Param::num_param_overrides = 0;
 
+/*
+  this holds default parameters in the normal NAME=value form for a
+  parameter file. It can be manipulated by apj_tool.py to change the
+  defaults on a binary without recompiling
+ */
+const AP_Param::param_defaults_struct AP_Param::param_defaults_data = {
+    "PARMDEF",
+    { 0x55, 0x37, 0xf4, 0xa0, 0x38, 0x5d, 0x48, 0x5b },
+    AP_PARAM_MAX_EMBEDDED_PARAM,
+    0
+};
+
 // storage object
 StorageAccess AP_Param::_storage(StorageManager::StorageParam);
 
@@ -1287,6 +1299,11 @@ bool AP_Param::load_all(bool check_defaults_file)
  */
 void AP_Param::reload_defaults_file(bool panic_on_error)
 {
+    if (param_defaults_data.length != 0) {
+        load_embedded_param_defaults(panic_on_error);
+        return;
+    }
+    
 #if HAL_OS_POSIX_IO == 1
     /*
       if the HAL specifies a defaults parameter file then override
@@ -1731,9 +1748,6 @@ void AP_Param::set_float(float value, enum ap_var_type var_type)
 }
 
 
-#if HAL_OS_POSIX_IO == 1
-#include <stdio.h>
-
 /*
   parse a parameter file line
  */
@@ -1759,6 +1773,10 @@ bool AP_Param::parse_param_line(char *line, char **vname, float &value)
     return true;
 }
 
+
+#if HAL_OS_POSIX_IO == 1
+#include <stdio.h>
+
 // increments num_defaults for each default found in filename
 bool AP_Param::count_defaults_in_file(const char *filename, uint16_t &num_defaults, bool panic_on_error)
 {
@@ -1886,6 +1904,129 @@ bool AP_Param::load_defaults_file(const char *filename, bool panic_on_error)
 
 #endif // HAL_OS_POSIX_IO
 
+/*
+  count the number of embedded parameter defaults
+ */
+bool AP_Param::count_embedded_param_defaults(uint16_t &count, bool panic_on_error)
+{
+    const volatile char *ptr = param_defaults_data.data;
+    uint16_t length = param_defaults_data.length;
+    count = 0;
+    
+    while (length) {
+        char line[100];
+        char *pname;
+        float value;
+        uint16_t i;
+        uint16_t n = MIN(length, sizeof(line)-1);
+        for (i=0;i<n;i++) {
+            if (ptr[i] == '\n') {
+                break;
+            }
+        }
+        if (i == n) {
+            // no newline
+            break;
+        }
+        
+        memcpy(line, (void *)ptr, i);
+        line[i] = 0;
+
+        length -= i+1;
+        ptr += i+1;
+        
+        if (line[0] == '#' || line[0] == 0) {
+            continue;
+        }
+
+        if (!parse_param_line(line, &pname, value)) {
+            continue;
+        }
+
+        enum ap_var_type var_type;
+        if (!find(pname, &var_type)) {
+            if (panic_on_error) {
+                ::printf("invalid param %s in defaults file\n", pname);
+                AP_HAL::panic("AP_Param: Invalid param in embedded defaults");
+            } else {
+                continue;
+            }
+        }
+        count++;
+    }
+    return true;
+}
+
+
+/*
+  load a default set of parameters from a embedded parameter region
+ */
+void AP_Param::load_embedded_param_defaults(bool panic_on_error)
+{
+    if (param_overrides != nullptr) {
+        free(param_overrides);
+        param_overrides = nullptr;
+    }
+    
+    num_param_overrides = 0;
+    uint16_t num_defaults = 0;
+    if (!count_embedded_param_defaults(num_defaults, panic_on_error)) {
+        return;
+    }
+
+    param_overrides = new param_override[num_defaults];
+    if (param_overrides == nullptr) {
+        AP_HAL::panic("AP_Param: Failed to allocate overrides");
+        return;
+    }
+    
+    const volatile char *ptr = param_defaults_data.data;
+    uint16_t length = param_defaults_data.length;
+    uint16_t idx = 0;
+    
+    while (length) {
+        char line[100];
+        char *pname;
+        float value;
+        uint16_t i;
+        uint16_t n = MIN(length, sizeof(line)-1);
+        for (i=0;i<n;i++) {
+            if (ptr[i] == '\n') {
+                break;
+            }
+        }
+        if (i == n) {
+            // no newline
+            break;
+        }
+        memcpy(line, (void*)ptr, i);
+        line[i] = 0;
+        
+        length -= i+1;
+        ptr += i+1;
+
+        if (line[0] == '#' || line[0] == 0) {
+            continue;
+        }
+        
+        if (!parse_param_line(line, &pname, value)) {
+            continue;
+        }
+        enum ap_var_type var_type;
+        AP_Param *vp = find(pname, &var_type);
+        if (!vp) {
+            continue;
+        }
+        param_overrides[idx].object_ptr = vp;
+        param_overrides[idx].value = value;
+        idx++;
+        if (!vp->configured_in_storage()) {
+            vp->set_float(value, var_type);
+        }
+    }
+    num_param_overrides = num_defaults;
+}
+
 /* 
    find a default value given a pointer to a default value in flash
  */
diff --git a/libraries/AP_Param/AP_Param.h b/libraries/AP_Param/AP_Param.h
index d6cc45099a..eb6518fbf2 100644
--- a/libraries/AP_Param/AP_Param.h
+++ b/libraries/AP_Param/AP_Param.h
@@ -31,6 +31,13 @@
 
 #define AP_MAX_NAME_SIZE 16
 
+/*
+  maximum size of embedded parameter file
+ */
+#ifndef AP_PARAM_MAX_EMBEDDED_PARAM
+#define AP_PARAM_MAX_EMBEDDED_PARAM 8192
+#endif
+
 /*
   flags for variables in var_info and group tables
  */
@@ -443,6 +450,19 @@ private:
 
     static uint16_t             _frame_type_flags;
 
+    /*
+      structure for built-in defaults file that can be modified using apj_tool.py
+     */
+    struct PACKED param_defaults_struct {
+        char magic_str[8];
+        uint8_t param_magic[8];
+        uint16_t max_length;
+        volatile uint16_t length;
+        volatile char data[AP_PARAM_MAX_EMBEDDED_PARAM];
+    };
+    static const param_defaults_struct param_defaults_data;
+    
+    
     static bool                 check_group_info(const struct GroupInfo *group_info, uint16_t *total_size, 
                                                  uint8_t max_bits, uint8_t prefix_length);
     static bool                 duplicate_key(uint16_t vindex, uint16_t key);
@@ -521,15 +541,22 @@ private:
     // find a default value given a pointer to a default value in flash
     static float get_default_value(const AP_Param *object_ptr, const float *def_value_ptr);
 
+    static bool parse_param_line(char *line, char **vname, float &value);
+    
 #if HAL_OS_POSIX_IO == 1
     /*
       load a parameter defaults file. This happens as part of load_all()
      */
-    static bool parse_param_line(char *line, char **vname, float &value);
     static bool count_defaults_in_file(const char *filename, uint16_t &num_defaults, bool panic_on_error);
     static bool read_param_defaults_file(const char *filename);
     static bool load_defaults_file(const char *filename, bool panic_on_error);
 #endif
+
+    /*
+      load defaults from embedded parameters
+     */
+    static bool count_embedded_param_defaults(uint16_t &count, bool panic_on_error);
+    static void load_embedded_param_defaults(bool panic_on_error);
     
     // send a parameter to all GCS instances
     void send_parameter(const char *name, enum ap_var_type param_header_type, uint8_t idx) const;