Merge pull request #18 from DavidAntliff/parasitic-power

Add support for parasitic power

.gitmodules

@@ -1,7 +1,6 @@
 [submodule "components/esp32-owb"]
     path = components/esp32-owb
-	url = https://github.com/DavidAntliff/esp32-owb
+    url = ../esp32-owb
 [submodule "components/esp32-ds18b20"]
     path = components/esp32-ds18b20
-    url = https://github.com/DavidAntliff/esp32-ds18b20
+    url = ../esp32-ds18b20
-

CMakeLists.txt

@@ -3,7 +3,7 @@
 cmake_minimum_required(VERSION 3.5)
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
-project(esp32-ds18b20-example)
+project(esp32-ds18b20-example LANGUAGES C)
 
 if (NOT IDF_VERSION_MAJOR)
   set(IDF_VERSION_MAJOR 3)

README.md

@@ -6,11 +6,13 @@
 
 ## Introduction
 
-This is an example application for the Maxim Integrated DS18B20 Programmable Resolution 1-Wire Digital Thermometer device.
+This is an example application for the Maxim Integrated DS18B20 Programmable Resolution 1-Wire Digital Thermometer 
+device.
 
 It supports a single or multiple devices on the same 1-Wire bus.
 
-It is written and tested for v3.3 of the [ESP-IDF](https://github.com/espressif/esp-idf) environment, using the xtensa-esp32-elf toolchain (gcc version 5.2.0, crosstool-ng-1.22.0-80-g6c4433a).
+It is written and tested for v3.3 and v4.1-beta1 of the [ESP-IDF](https://github.com/espressif/esp-idf) environment,
+using the xtensa-esp32-elf toolchain (gcc version 5.2.0, crosstool-ng-1.22.0-80-g6c4433a).
 
 Ensure that submodules are cloned:
 
@@ -23,7 +25,8 @@ Build the application with:
     $ idf.py build
     $ idf.py -p (PORT) flash monitor
 
-The program should detect your connected devices and periodically obtain temperature readings from them, displaying them on the console.
+The program should detect your connected devices and periodically obtain temperature readings from them, displaying them
+on the console.
 
 ## Dependencies
 
@@ -34,17 +37,27 @@ This application makes use of the following components (included as submodules):
 
 ## Hardware
 
-To run this example, connect one or more DS18B20 devices to a single GPIO on the ESP32. Use the recommended pull-up resistor of 4.7 KOhms, connected to the 3.3V supply.
+To run this example, connect one or more DS18B20 devices to a single GPIO on the ESP32. Use the recommended pull-up 
+resistor of 4.7 KOhms, connected to the 3.3V supply.
 
 `idf.py menuconfig` can be used to set the 1-Wire GPIO.
 
-If you have several devices and see occasional CRC errors, consider using a 2.2 kOhm pull-up resistor instead. Also consider adding decoupling capacitors between the sensor supply voltage and ground, as close to each sensor as possible.
+If you have several devices and see occasional CRC errors, consider using a 2.2 kOhm pull-up resistor instead. Also 
+consider adding decoupling capacitors between the sensor supply voltage and ground, as close to each sensor as possible.
+
+If you wish to enable a second GPIO to control an external strong pull-up circuit for parasitic power mode, ensure 
+`CONFIG_ENABLE_STRONG_PULLUP=y` and `CONFIG_STRONG_PULLUP_GPIO` is set appropriately.
+ 
+See documentation for [esp32-ds18b20](https://www.github.com/DavidAntliff/esp32-ds18b20-example#parasitic-power-mode)
+for further information about parasitic power mode, including strong pull-up configuration.
+
 
 ## Features
 
 This example provides:
 
- * External power supply mode.
+ * External power supply detection.
+ * Parasitic power supply detection.
  * Static (stack-based) or dynamic (malloc-based) memory model examples.
  * No global variables.
  * Device search.

components/esp32-ds18b20

@@ -1 +1 @@
-Subproject commit d76b70c0a795adbbd1b9d1b3e2789b455cfd945d
+Subproject commit e763961d445263cdfc93d0fe516f917ba95a43e1

components/esp32-owb

@@ -1 +1 @@
-Subproject commit af25dd31dbb1e80364b99fad29815badfab0ceda
+Subproject commit 316296a398e44976a5abdd7d70f8c21ad2cec09d

main/Kconfig.projbuild

@@ -2,13 +2,45 @@ menu "esp32-ds18b20-example Configuration"
 
 config ONE_WIRE_GPIO
     int "OneWire GPIO number"
-	range 0 34
+	range 0 33
-	default 5
+	default 4
 	help
 		GPIO number (IOxx) to access One Wire Bus.
 
 		Some GPIOs are used for other purposes (flash connections, etc.) and cannot be used.
 
-		GPIOs 35-39 are input-only so cannot be used to drive the One Wire Bus.
+		GPIOs 34-39 are input-only so cannot be used to drive the One Wire Bus.
+
+config ENABLE_STRONG_PULLUP_GPIO
+    bool "Enable strong pull-up controlled by GPIO (MOSFET)"
+    default n
+    help
+        An external circuit can be used to provide a strong pull-up to the One Wire Bus.
+        This is useful when the bus has parasitic-powered devices and extra current is
+        required to power them, such as during temperature ADC conversions.
+
+        An example of such a circuit for the ESP32 is a P-channel MOSFET (such as the BS250)
+        connected Source-to-Drain between a current-limiting resistor (e.g. 270ohm for 12mA
+        max at 3.3V), itself connected to VCC, and the One Wire Bus data line. The Gate is
+        connected to the GPIO specified here.
+
+config STRONG_PULLUP_GPIO
+    int "Strong pull-up GPIO number"
+    range 0 33
+    default 5
+    help
+		GPIO number (IOxx) to control the strong pull-up on the One Wire Bus, perhaps
+		via a P-channel MOSFET between VCC and the One Wire Bus data line.
+
+		This GPIO will be set as an output and driven high during temperature conversion.
+		This would enable the MOSFET providing current to the devices.
+
+		At all other times it will be driven low, switching off the MOSFET and allowing
+		the One Wire Bus to operate normally.
+
+		Some GPIOs are used for other purposes (flash connections, etc.) and cannot be used.
+
+		GPIOs 34-39 are input-only so cannot be used to drive the One Wire Bus.
+    depends on ENABLE_STRONG_PULLUP_GPIO
 
 endmenu

main/app_main.c

@@ -22,8 +22,6 @@
  * SOFTWARE.
  */
 
-#include <inttypes.h>
-
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "esp_system.h"
@@ -38,7 +36,7 @@
 #define DS18B20_RESOLUTION   (DS18B20_RESOLUTION_12_BIT)
 #define SAMPLE_PERIOD        (1000)   // milliseconds
 
-void app_main()
+_Noreturn void app_main()
 {
     // Override global log level
     esp_log_level_set("*", ESP_LOG_INFO);
@@ -150,6 +148,23 @@ void app_main()
 //        vTaskDelay(1000 / portTICK_PERIOD_MS);
 //    }
 
+    // Check for parasitic-powered devices
+    bool parasitic_power = false;
+    ds18b20_check_for_parasite_power(owb, &parasitic_power);
+    if (parasitic_power) {
+        printf("Parasitic-powered devices detected");
+    }
+
+    // In parasitic-power mode, devices cannot indicate when conversions are complete,
+    // so waiting for a temperature conversion must be done by waiting a prescribed duration
+    owb_use_parasitic_power(owb, parasitic_power);
+
+#ifdef CONFIG_ENABLE_STRONG_PULLUP_GPIO
+    // An external pull-up circuit is used to supply extra current to OneWireBus devices
+    // during temperature conversions.
+    owb_use_strong_pullup_gpio(owb, CONFIG_STRONG_PULLUP_GPIO);
+#endif
+
     // Read temperatures more efficiently by starting conversions on all devices at the same time
     int errors_count[MAX_DEVICES] = {0};
     int sample_count = 0;

sdkconfig.defaults

@@ -0,0 +1,4 @@
+#
+# Log output
+#
+CONFIG_LOG_DEFAULT_LEVEL=4