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-# LightTAM_RFID_Reader
+# LightTAM RFID Reader
+
+This is firmware for an RFID reader for the LightTAM software. The LightTAM repository is [here](https://git.edcs.cz/eduard.dlabal). The LightTAM RFID Reader is built using an STM32F103C8 controller (mainly sold on BluePill boards), a PN532 RFID reader, and an HD44780 LCD display for the I2C bus. MCU is programmed using STM32Cube with CMake and HAL libraries. For editing (or debugging), I recommend using VS Code with STM32Cube extension installed. 
+
+This program utilizes libraries from these repositories:
+- [STM32_HAL_I2C_HD44780](https://github.com/eziya/STM32_HAL_I2C_HD44780)
+- [pn532-lib](https://github.com/soonuse/pn532-lib)
+
+## Hardware Connection
+
+- **PN532 RFID Reader**: Connected via UART or I2C (depending on configuration).
+- **HD44780 LCD Display**: Connected via I2C using a PCF8574 I/O expander.
+- **Three LEDs**: Connected to PB12 (red), PB13 (yellow), and PB14 (green).
+- **Power Supply**: 5V input, regulated to 3.3V for the STM32 and peripherals.
+
+### Wiring
+
+| Device         | STM32 Pin      | Notes                |
+|----------------|---------------|----------------------|
+| PN532 (I2C)    | PB6 (SCL)     | I2C1 SCL             |
+|                | PB7 (SDA)     | I2C1 SDA             |
+| LCD (I2C)      | PB6 (SCL)     | Shared I2C bus       |
+|                | PB7 (SDA)     | Shared I2C bus       |
+| LED Red        | PB12          |                      |
+| LED Yellow     | PB13          |                      |
+| LED Green      | PB14          |                      |
+| Computer (RXD) | A2 | USART2 TX
+Computer (TXD)    | A3         |      USART2 RX                |
+|Debug (RXD)|PA9|USART1 TX
+|Debug (TXD)|PA10|USART1 TX
+
+## Firmware Operation
+
+After startup, the firmware initializes all peripherals: I2C, GPIOs, the LCD display, and the PN532 RFID reader. The main loop performs the following steps:
+
+1. **Idle State**:  
+   - The green LED (PB14) is ON, indicating the system is ready to scan for RFID tags.
+   - The LCD displays a welcome or ready message.
+
+2. **RFID Scanning**:  
+   - The firmware continuously polls the PN532 for the presence of an RFID tag.
+
+3. **Tag Detection**:  
+   - When a tag is detected, the UID is read.
+   - The yellow LED (PB13) briefly turns ON to indicate a tag is being processed.
+   - The LCD displays the UID or relevant information.
+
+4. **Tag Validation**:  
+   - The firmware checks if the tag UID is valid (e.g., against a list or via communication with the host).
+   - If the tag is valid, the green LED (PB14) blinks or stays ON.
+   - If the tag is invalid, the red LED (PB12) turns ON to indicate an error or unauthorized tag.
+
+5. **Status Indication**:  
+   - The LEDs provide immediate feedback:
+     - **Green (PB14)**: System ready or access granted.
+     - **Yellow (PB13)**: Tag detected and being processed.
+     - **Red (PB12)**: Error or access denied.
+
+6. **Communication**:  
+   - The firmware can send the UID or status to a host system via UART or another interface if required.
+
+7. **Return to Idle**:  
+   - After processing, the system returns to the idle state, with the green LED ON and others OFF.
+
+All logic is implemented using STM32Cube HAL libraries. The code is organized under the `Core/` and `Drivers/` directories.