diff --git a/main/ds18b20.c b/main/ds18b20.c
index f202652..14d54e6 100644
--- a/main/ds18b20.c
+++ b/main/ds18b20.c
@@ -63,6 +63,7 @@ DS18B20_Info * ds18b20_malloc(void)
 	if (ds18b20_info != NULL)
 	{
 		memset(ds18b20_info, 0, sizeof(*ds18b20_info));
+		ESP_LOGD(TAG, "malloc %p", ds18b20_info);
 	}
 	else
 	{
@@ -76,7 +77,8 @@ void ds18b20_free(DS18B20_Info ** ds18b20_info)
 {
 	if (ds18b20_info != NULL && (*ds18b20_info != NULL))
 	{
-		free(ds18b20_info);
+		ESP_LOGD(TAG, "free %p", *ds18b20_info);
+		free(*ds18b20_info);
 		*ds18b20_info = NULL;
 	}
 }
diff --git a/main/ds18b20_main.c b/main/ds18b20_main.c
index 911853b..b7d5573 100644
--- a/main/ds18b20_main.c
+++ b/main/ds18b20_main.c
@@ -4,7 +4,15 @@
 #include "freertos/task.h"
 #include "esp_system.h"
 
-#include "ds18b20.h"
+//#define USE_STATIC 1
+
+#ifdef USE_STATIC
+#  include "owb_static.h"
+#  include "ds18b20_static.h"
+#else
+#  include "owb.h"
+#  include "ds18b20.h"
+#endif
 
 
 #define GPIO_DS18B20_0 (GPIO_NUM_4)
@@ -13,7 +21,13 @@
 void app_main()
 {
 	// Create a 1-Wire bus
-	OneWireBus * owb = owb_malloc();
+#ifdef USE_STATIC
+	OneWireBus_Static owb_static;        // static allocation
+	OneWireBus * owb = &owb_static;
+#else
+	OneWireBus * owb = owb_malloc();     // heap allocation
+#endif
+
 	owb_init(owb, GPIO_DS18B20_0);
     owb_use_crc(owb, true);              // enable CRC check for ROM code
 
@@ -22,7 +36,14 @@ void app_main()
     uint64_t rom_code = owb_read_rom(owb);
 	printf("1-Wire ROM code 0x%08" PRIx64 "\n", rom_code);
 
-	DS18B20_Info * ds18b20_info = ds18b20_malloc();
+	// Create a DS18B20 device on the 1-Wire bus
+#ifdef USE_STATIC
+	DS18B20_Info_Static ds18b20_info_static;       // static allocation
+	DS18B20_Info * ds18b20_info = &ds18b20_info_static;
+#else
+	DS18B20_Info * ds18b20_info = ds18b20_malloc();  // heap allocation
+#endif
+
 	ds18b20_init(ds18b20_info, owb, rom_code);     // associate with bus and device
 	//ds18b20_init_solo(ds18b20_info, owb);          // only one device on bus
 	ds18b20_use_crc(ds18b20_info, true);           // enable CRC check for temperature readings
@@ -39,7 +60,7 @@ void app_main()
         vTaskDelay(1000 / portTICK_PERIOD_MS);
     }
 
-    //ds18b20_free(&ds18b20_info);
+    ds18b20_free(&ds18b20_info);
     	owb_free(&owb);
 
     printf("Restarting now.\n");
diff --git a/main/ds18b20_static.h b/main/ds18b20_static.h
new file mode 100644
index 0000000..3501098
--- /dev/null
+++ b/main/ds18b20_static.h
@@ -0,0 +1,29 @@
+// Expose structure for stack-based (static) allocation.
+
+#ifndef DS18B20_STATIC_H
+#define DS18B20_STATIC_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "ds18b20.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct _DS18B20_Info
+{
+	bool init;
+	bool use_crc;
+	OneWireBus * bus;
+	uint64_t rom_code;
+};
+
+typedef struct _DS18B20_Info DS18B20_Info_Static;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // DS18B20_STATIC_H
diff --git a/main/owb.c b/main/owb.c
index c035e02..1fba20b 100644
--- a/main/owb.c
+++ b/main/owb.c
@@ -8,6 +8,7 @@
 #include "driver/gpio.h"
 
 #include "owb.h"
+#include "owb_static.h"
 
 #define TAG "owb"
 
@@ -31,13 +32,13 @@ static const struct _OneWireBus_Timing _StandardTiming = {
 	410 * 4,  // J
 };
 
-struct _OneWireBus
-{
-	bool init;
-	int gpio;
-	const struct _OneWireBus_Timing * timing;
-	bool use_crc;
-};
+//struct _OneWireBus
+//{
+//	bool init;
+//	int gpio;
+//	const struct _OneWireBus_Timing * timing;
+//	bool use_crc;
+//};
 
 static void _tick_delay(int ticks)
 {
@@ -204,7 +205,7 @@ static uint8_t * _read_block(const OneWireBus * bus, uint8_t * buffer, unsigned
  * @param[in] len Number of bytes to write.
  * @return Pointer to write buffer.
  */
-static uint8_t * _write_block(const OneWireBus * bus, const uint8_t * buffer, unsigned int len)
+static const uint8_t * _write_block(const OneWireBus * bus, const uint8_t * buffer, unsigned int len)
 {
 	for (int i = 0; i < len; ++i)
 	{
@@ -253,6 +254,7 @@ OneWireBus * owb_malloc()
 	if (bus != NULL)
 	{
 		memset(bus, 0, sizeof(*bus));
+		ESP_LOGD(TAG, "malloc %p", bus);
 	}
 	else
 	{
@@ -265,7 +267,8 @@ void owb_free(OneWireBus ** bus)
 {
 	if (bus != NULL && (*bus != NULL))
 	{
-		free(bus);
+		ESP_LOGD(TAG, "free %p", *bus);
+		free(*bus);
 		*bus = NULL;
 	}
 }
@@ -367,7 +370,7 @@ uint8_t * owb_read_bytes(const OneWireBus * bus, uint8_t * buffer, unsigned int
 	return _read_block(bus, buffer, len);
 }
 
-uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len)
+const uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len)
 {
 	return _write_block(bus, buffer, len);
 }
diff --git a/main/owb.h b/main/owb.h
index 3ff69bc..f28693a 100644
--- a/main/owb.h
+++ b/main/owb.h
@@ -91,7 +91,7 @@ uint8_t owb_read_byte(const OneWireBus * bus);
   * @param[in] len Number of bytes to write.
   * @return Pointer to write buffer.
   */
-uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len);
+const uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len);
 
 /**
  * @brief Write a ROM code to the 1-Wire bus ensuring LSB is sent first.
@@ -113,4 +113,4 @@ void owb_write_rom_code(const OneWireBus * bus, uint64_t rom_code);
 }
 #endif
 
-#endif  // DS18B20_H
+#endif  // ONE_WIRE_BUS_H
diff --git a/main/owb_static.h b/main/owb_static.h
new file mode 100644
index 0000000..17a8b2e
--- /dev/null
+++ b/main/owb_static.h
@@ -0,0 +1,28 @@
+// Expose structure for stack-based (static) allocation.
+
+#ifndef ONE_WIRE_BUS_STATIC_H
+#define ONE_WIRE_BUS_STATIC_H
+
+#include <stdbool.h>
+
+#include "owb.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct _OneWireBus
+{
+	bool init;
+	int gpio;
+	const struct _OneWireBus_Timing * timing;
+	bool use_crc;
+};
+
+typedef struct _OneWireBus OneWireBus_Static;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // ONE_WIRE_BUS_STATIC_H