diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index feb0e0b..5d7fa59 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -41,9 +41,7 @@ jobs:
     - name: Find firmware binaries
       id: build_run
       run: |
-        RUN_ID=$(gh api \
-          "repos/${{ github.repository }}/actions/workflows/build.yml/runs?head_sha=${{ github.sha }}&per_page=1" \
-          --jq '.workflow_runs[0].id')
+        RUN_ID=$(gh api "repos/${{ github.repository }}/actions/workflows/build.yml/runs?head_sha=${{ github.sha }}&per_page=1" --jq '.workflow_runs[0].id')
         echo "id=$RUN_ID" >> $GITHUB_OUTPUT
       env:
         GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -55,7 +53,7 @@ jobs:
         run-id: ${{ steps.build_run.outputs.id }}
         name: firmware-binary
         path: docs/build
-    - name: Create shortcuts
+    - name: Create shortcuts for firmware binaries
       working-directory: docs/build
       run: |
         for FQBN in esp32.esp32.*; do
diff --git a/docs/usage.md b/docs/usage.md
index d64ced0..1b8b13f 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -4,9 +4,9 @@ To fly Flix quadcopter, you need to upload the firmware to the ESP32 board, and
 
 ## Uploading the firmware
 
-You can either use the **prebuilt binaries** or **build the firmware** from sources — this will let you modify the firmware and add new features.
+You can either use the **prebuilt binaries** or **build the firmware** from sources — this will let you modify the firmware and add new features.
 
-## Prebuilt binaries (the easiest way)
+### Prebuilt binaries (the easiest way)
 
 1. Download the latest firmware file using the following links:
 
@@ -22,14 +22,15 @@ You can either use the **prebuilt binaries** or **build the firmware** from sour
    <!-- markdownlint-enable MD044 -->
 
 2. Flash your ESP32 board using [ESP32 Web Flasher](https://www.espboards.dev/tools/program/):
+
+   <img src="img/web-flasher.png" width="400">
+
    * Connect the board to your computer, press *Connect to ESP*, choose the serial port.
    * Go to the *Flash* tab.
-   * Choose the downloaded firmware file, set *Flash address* to *0*.
+   * Choose the downloaded firmware file, set *Flash address* to *0* (important).
    * Click *Program* button and wait until the process is finished.
 
-<img src="img/web-flasher.png" width="400">
-
-## Building from sources (flexible)
+### Building from sources (flexible)
 
 You can build and upload the firmware using either **Arduino IDE** (easier for beginners) or **command line**.
 
@@ -41,7 +42,7 @@ git clone https://github.com/okalachev/flix.git && cd flix
 
 Beginners can [download the sources as a ZIP archive](https://github.com/okalachev/flix/archive/refs/heads/master.zip).
 
-### Arduino IDE (Windows, Linux, macOS)
+#### Arduino IDE (Windows, Linux, macOS)
 
 <img src="img/arduino-ide.png" width="400" alt="Flix firmware open in Arduino IDE">
 
@@ -56,7 +57,7 @@ Beginners can [download the sources as a ZIP archive](https://github.com/okalach
 7. Set *Tools* ⇒ *Core Debug Level* to *Error* to see the errors in the serial console. Set *Tools* ⇒ *USB CDC on Boot* to *Enabled* for ESP32-S3/ESP32-C3 boards.
 8. [Build and upload](https://docs.arduino.cc/software/ide-v2/tutorials/getting-started/ide-v2-uploading-a-sketch) the firmware using Arduino IDE.
 
-### Command line (Windows, Linux, macOS)
+#### Command line (Windows, Linux, macOS)
 
 1. [Install Arduino CLI](https://arduino.github.io/arduino-cli/installation/).
 
@@ -141,7 +142,7 @@ You can also work with parameters using `p` command in the console. Parameter na
 ### Configure the IMU
 
 1. Configure the following parameters for the IMU:
-   * `IMU_MODEL` — IMU model (1 for MPU-9250/MPU-6500¹, 2 for ICM-20948, 3 for MPU-6050, 4 for ICM-40609-D).
+   * `IMU_MODEL` — IMU model (1 for MPU-9250/MPU-6500, 2 for ICM-20948, 3 for MPU-6050, 4 for ICM-40609-D).
    * `IMU_BUS` — communication bus (0 for SPI, 1 for I²C).
    * `IMU_PIN_SCK`, `IMU_PIN_MISO`, `IMU_PIN_MOSI`, `IMU_PIN_CS` — SPI pin numbers.
    * `IMU_PIN_SCL`, `IMU_PIN_SDA` — I²C pin numbers.
@@ -149,8 +150,6 @@ You can also work with parameters using `p` command in the console. Parameter na
 2. Reboot the drone.
 3. Check the IMU is working using `imu` command in the console (should print `status: OK`).
 
-¹ — not to be confused with MPU-6050.
-
 ### Define IMU orientation
 
 The IMU orientation (relative to the drone's axes) is defined using the parameters: `IMU_ROT_ROLL`, `IMU_ROT_PITCH`, and `IMU_ROT_YAW`.
@@ -181,7 +180,7 @@ If using non-default motor pins, set the pin numbers using the parameters: `MOTO
 
 #### Brushless motors
 
-In case of using brushless motors with ESCs:
+If using brushless motors with ESCs:
 
 1. Set the appropriate PWM using the parameters: `MOT_PWM_STOP`, `MOT_PWM_MIN`, and `MOT_PWM_MAX` (1000, 1000, and 2000 is typical).
 2. Decrease the PWM frequency using the `MOT_PWM_FREQ` parameter (400 is typical).
diff --git a/flix/motors.ino b/flix/motors.ino
index 959a951..6b808b1 100644
--- a/flix/motors.ino
+++ b/flix/motors.ino
@@ -7,7 +7,7 @@
 
 float motors[4]; // normalized motor thrusts in range [0..1]
 
-int motorPins[4] = {-1, -1, -1, -1}; // default pin numbers
+int motorPins[4] = {12, 13, 14, 15}; // default pin numbers
 int pwmFrequency = 78000;
 int pwmResolution = 10;
 int pwmStop = 0;
diff --git a/gazebo/flix.h b/gazebo/flix.h
index 37d12c8..99f6e89 100644
--- a/gazebo/flix.h
+++ b/gazebo/flix.h
@@ -24,7 +24,6 @@ LowPassFilter<Vector> gyroBiasFilter(0);
 int imuModel = 1, imuBus = 0;
 int imuSckPin = 0, imuMisoPin = 0, imuMosiPin = 0, imuCsPin = -1, imuIntPin = -1;
 int imuSdaPin = 0, imuSclPin = 0;
-int rgbPin = -1, rgbNum = 1;
 
 // declarations
 void step();