This article contains actionable advice on WiFi provisioning and was kindly contributed by a valued member of Blynk.Community PeteKnight.
Sometimes new Blynkers get confused about how the dynamic provisioning process works in the Edgent sketch examples, and how to re-provision a device with new WiFi credentials. Some users omit to configure the board type correctly in the sketch, which also causes issues.
Here’s a detailed guide to how the whole process works, and the things to watch out for…
You start by creating a template, preferably in the web console (https://blynk.cloud/)
This gives you the BLYNK_TEMPLATE_ID and BLYNK_DEVICE_NAME that you copy/paste into the Edgent example sketch, replacing the existing lines of code that are commented-out.
To do the Edgent provisioning/re-provisioning process correctly need a physical switch and an LED connected to your board. Some boards have these already, some need to have them added by you. This is covered in detail in the “Defining your physical switch and LED” section below.
In the app, you then use the “+ Add New Device” option to connect to the device and supply the WiFi credentials.
The WiFi credentials (and the current Auth token) can be cleared by pressing and holding the physical button for 10 seconds. New WiFi credentials and a new auth token can be provisioned to an existing device using the “Reconfigure” option in the app.
The Device Name is the name that you provide when you create the template, and the Edgent sketch then adds additional characters that are derived from the Chip ID of the device to give the SSID which is used when the app connects to the device during the provisioning phase.
If the device name + Chip ID exceeds 32 characters then the provisioning process won’t complete successfully, so keep the template name to a reasonable length.
This is the area that is probably most confusing to new users of the Edgent sketch, especially if they are unfamiliar with the #define, #if defined, #elif and #endif commands in C++.
I’ll use the Edgent_ESP8266 sketch as an example, but the same principles apply to the ESP32 sketch as well.
The Edgent_ESP8266.ino file (the first tab in the Arduino IDE) contains the following lines of code:
Notice that all of these board types are commented-out by default.
Your first task should be to un-comment one of these board types, then look in the Settings.h tab so that you understand what the code is doing, and what additional steps you may need to take.
If the board you are using isn’t listed here then leaving all of the board types commented out will cause the sketch to use the “Custom board configuration” from the Settings.h tab, and you need to edit this custom configuration to suit your hardware.
This is what the relevant parts of the standard Settings.h file look like:
The first section starts with #if defined(USE_NODE_MCU_BOARD) || defined(USE_WEMOS_D1_MINI).
In plain English, this means, “If you’ve uncommented either the #define USE_NODE_MCU_BOARD or #define USE_WEMOS_D1_MINI lines of code in the first tab of the sketch, then the following settings will be used for the physical button and LED”.
The NodeMCU board has 2 physical buttons:
Image credits to RandomNerdTutorials
The button on the bottom left is labeled RST and the one on the bottom right is labeled FLASH.
The FLASH button is connected to GPIO0 (the pin labeled D3 on the board). When the button is pressed, GPIO0 is connected to GND (LOW).
All NodeMCUs that I’ve come across also have a built-in LED (located up near the top right of the board) which is connected to GPIO2 (the pin labeled D4). This LED lights up when GPIO2 is pulled LOW, so has what is known as inverse logic.
Some NodeMCUs also have an additional LED (down near the bottom left of the board) which is connected to GPIO16 (The pin labeled D0). This LED also works in “Inverted” mode – it lights up when the pin is pulled LOW.
Going back to the standard settings for the NodeMCU/Wemos D1 Mini board, you should now understand these settings in relation to the board, but I’ve added some comments next to each line to explain them further…
If you’re using the Wemos D1 mini, it is very similar:
Image credits to RandomNerdTutorials but you’ll notice that it only has one button labeled RESET (same as the RST button on the NodeMCU).
It doesn’t have the FLASH button, so you’ll need to add a physical momentary push to make a button in order to be able to clear the stored credentials if ever you need to re-provision the board.
One side of the physical push button will connect to the pin labeled D3 and the other side to GND (because we have this line set to true:
#define BOARD_BUTTON_ACTIVE_LOW true
which means that when the button is pressed the GPIO0 (D3) pin is pulled LOW).
Of course, if you wanted to, you could simply use a jumper wire, bent paperclip, or anything else that’s conductive to short-out pin D3 and GND for 10 seconds if you are feeling lazy.
So, if you don’t un-comment one of the pre-defined board types, the custom board type configuration will be used. That looks like this:
As you can see, this uses GPIO0 (Pin D3) for the physical pushbutton switch, but GPIO4 (pin D2) for the LED. It also has the option to un-comment additional lines of code that allow an RGB or WS2812 RGB LED to be used.
If you didn’t un-comment any board types and allowed the custom board configuration to be used, then with a NodeMCU the built-in LED wouldn’t flash to indicate provisioning or pulse to indicate normal running. But, pin GPIO4 would still be receiving these pulses from the sketch, and if you had a sensor or relay attached to GPIO4 then this could provide unexpected results.
So, the important points are:
Once you’ve added the BLYNK_TEMPLATE_ID and BLYNK_DEVICE_NAME to your sketch, configured the correct board type, and uploaded the sketch to your board you are ready to do the provisioning.
It’s always a good idea to have the board connected to your computer and the serial monitor open so that you can see the debug information that’s being provided in the serial output.
The LED on the board should be flashing quickly.
Open the app and tap the three horizontal bars in the top right-hand corner then tap “+ Add new device”. Choose “Connect to WiFi” and confirm that the device is ready to be provisioned (LED blinking) by tapping “Ready” in the app.
The app will then scan for devices waiting to be provisioned, show you the device details and ask for permission to join the network (select Join), then ask you to select the SSID and enter the WiFi password.
Once you’ve done this the data is sent to the device and stored in its EEPROM, and you can exit the “Add device" when asked (Apply, Done, Exit to App).
The device will then appear on the initial screen of the app, ready to have widgets added to its mobile dashboard.
If the LED on the board isn’t doing anything, then go back and check the “Defining your physical switch and LED” section to ensure that the LED and switch are defined correctly and that you don’t have any peripherals also using the LED or Switch pins.
If the LED is pulsing slowly then the board thinks it’s already provisioned. Follow the instructions in the “Re-provisioning new WiFi credentials” section below.
If the LED is flashing quickly, but the device doesn’t show up in the app when you tap the “Ready” button in the app then check the following:
Re-provisioning new WiFi credentials
If you’re having problems provisioning a device, or you’ve accidentally entered the wrong WiFi credentials, then press and hold the physical button (the one defined in Settings.h for your board type) for 10 seconds. This will clear the stored credentials and the LED will start flashing quickly and allow you to either repeat the provisioning process, or if the device has already been created in the app you can re-provision it.
To re-provision an existing device, tap on the device in the app, then tap the three dots in the top right-hand corner of the app screen. This will bring up the device information/timeline screen.
Tap on the three dots in the top right-hand corner once more, and this will pop up a dialog that allows you to “Reconfigure”, “Erase all device data”, “Delete Device” or “Cancel”.
Choose “Reconfigure” and this will take you back into the provisioning process described in the earlier section.
If the wrong SSID was selected and/or the password was entered before then take care to enter the correct information rather than using the credentials stored in the app.