Starting firmware on the core¶
On this page you create a firmware project, bring the ESP32 to Online state on the portal, and verify that the network part works. Sensors and heating logic will be added in the following steps.
The approach is built on the iDryer::Link facade. You describe the device with a single iDryer::Config structure, call link.begin() and link.loop() — the core handles all network connection itself.
1. Prepare the tools¶
You will need:
- VS Code with PlatformIO extension;
- USB cable;
- Wi-Fi network
2.4 GHz(ESP32 does not work with5 GHzonly networks).
For information on what controller firmware is and how it gets into the board — see Controller firmware.
2. Create a project¶
In PlatformIO a project is a folder with a fixed structure. Create a project folder (for example my-cabinet) and open it in VS Code. Inside should be these files:
my-cabinet/
├── platformio.ini # build settings (fill in step 4)
├── include/
│ └── secrets.h # Wi-Fi login and password (step 3)
├── lib/
│ └── idryer-core/ # core library (symlink or copy)
└── src/
└── main.cpp # device code: Config + setup() + loop()
All code fragments below go into these specific files — each step indicates which file. Create the include/, lib/ and src/ folders manually if they don't exist.
Place the idryer-core library in lib/ — PlatformIO automatically finds libraries there. The easiest way is to create a symlink to the downloaded library:
This is also required for menu generation (chapter 6) — the hook looks for the generator inside lib/idryer-core/.
3. Create secrets.h¶
Copy the secrets.h.example example from the library to include/secrets.h in your project and specify your network credentials:
Add include/secrets.h to .gitignore so the password doesn't end up in the repository.
4. Configure platformio.ini¶
Fill in platformio.ini in the project root:
[env:cabinet]
platform = espressif32
framework = arduino
board = esp32-c3-devkitm-1
lib_deps =
bblanchon/ArduinoJson @ ^6.21.0
knolleary/PubSubClient
densaugeo/base64 @ ^1.4.0
links2004/WebSockets @ ^2.4.0
https://github.com/jnthas/Improv-WiFi-Library.git
build_flags =
-DIDRYER_API_BASE='"https://portal.idryer.org/api"'
-DMQTT_BROKER='"mqtt.idryer.org"'
-DMQTT_PORT=8883
-DMQTT_USE_TLS=1
Replace board with your board (for example, esp32-s3-devkitc-1). You don't need to specify idryer-core in lib_deps — it's located in lib/ (step 2).
Why all these dependencies
ArduinoJson, PubSubClient, base64, WebSockets and Improv-WiFi-Library are required by the idryer-core library itself (MQTT, WebSocket access over LAN, Wi-Fi provisioning). Without any of them the build will fail with an error like ... .h: No such file. The MQTT_BROKER and MQTT_PORT flags are also required — without them the core won't compile ('MQTT_BROKER' was not declared).
5. Describe the device in Config¶
Next, everything happens in one file — src/main.cpp. Open it and write the code from this and the following steps.
iDryer::Config is the device's passport. The has* flags tell the portal what the device has and determine which telemetry fields are published.
Add to the beginning of src/main.cpp:
#include <iDryer.h>
static const iDryer::Config CFG = {
.deviceType = iDryer::DeviceType::Dryer,
.unitsCount = 1,
// Peripherals:
.hasHeater = true, // controlled heater
.hasFan = true, // fan
.hasAirTemp = true, // air temperature (SHT31)
.hasAirHumidity = true, // air humidity (SHT31)
.hasHeaterTemp = true, // heater temperature (thermistor)
// Auto-publish periods:
.telemetryPeriodMs = 5000,
.statusPeriodMs = 10000,
// Portal identification:
.hardwareVersion = "1.0",
.firmwareVersion = "0.1.0",
.model = "DIY Storage Cabinet",
};
static iDryer::Link s_link(CFG);
has* flags are a contract with the portal
A telemetry field whose corresponding flag is false is not published. For example, without hasAirHumidity = true humidity won't be sent to the cloud, even if you write it in the code. Enable only what physically exists in the device.
For a complete list of components and flags — see System components.
6. Minimal main¶
In the same file after the Config block, add the setup() and loop() functions. For the first launch it's enough to initialize the link and run it in loop():
This is enough for the device to connect to Wi-Fi and reach the portal. We'll add sensors in the Sensors step.
Complete src/main.cpp after this chapter¶
Combine both blocks above into one file — this is the entire src/main.cpp at this stage:
#include <iDryer.h>
static const iDryer::Config CFG = {
.deviceType = iDryer::DeviceType::Dryer,
.unitsCount = 1,
.hasHeater = true,
.hasFan = true,
.hasAirTemp = true,
.hasAirHumidity = true,
.hasHeaterTemp = true,
.telemetryPeriodMs = 5000,
.statusPeriodMs = 10000,
.hardwareVersion = "1.0",
.firmwareVersion = "0.1.0",
.model = "DIY Storage Cabinet",
};
static iDryer::Link s_link(CFG);
void setup() {
Serial.begin(115200);
s_link.begin();
}
void loop() {
s_link.loop();
}
Previous chapters show what to add and the complete src/main.cpp after changes, so you always see the full picture rather than scattered pieces.
7. Flash the firmware¶
8. Open Serial Monitor¶
Expected sequence in the log:
[CLOUD] Connecting to WiFi...
[CLOUD] WiFi connected, IP: 192.168.1.42
[CLOUD] Provisioning device...
[CLOUD] PIN: 1234567 (expires in 600s)
If the device stops at the PIN: ... line — this is normal. Proceed to pairing.
9. Pair the device with the portal¶
- Open portal.idryer.org.
- Go to the Add device section.
- Enter the PIN from Serial Monitor.
After pairing, the device will transition to Online status. The log will show:
Verification¶
At this stage the device should be Online on the portal. There's no sensor data yet — this is expected. If the device doesn't connect:
- verify that the
2.4 GHznetwork and password insecrets.hare correct; - check the ESP32 power supply (voltage drops on startup are a common cause of resets);
- see Power mistakes and Controller mistakes.
What's next¶
The network part is working. Move on to Sensors: we'll connect the SHT31 and thermistor and see their data on the portal.