PROCEDURE EEPROM_WriteEnable()
    SET command = 0x06 (WREN command)

    PULL CS line LOW
    SEND command over SPI
    PULL CS line HIGH
END PROCEDURE

PROCEDURE EEPROM_WriteByte(address, data_byte)
    IF address > 0x3FF THEN
        RETURN (address out of range)
    END IF

    CREATE command_array with 3 elements:
        command_array[0] = 0x02 (WRITE instruction)
        command_array[1] = upper 3 bits of address (A10-A8)
        command_array[2] = lower 8 bits of address (A7-A0)

    CALL EEPROM_WriteEnable() to enable writing
    PULL CS line LOW
    SEND command_array (3 bytes) over SPI
    SEND data_byte over SPI
    PULL CS line HIGH

    CALL EEPROM_WaitWriteComplete() to wait for completion
END PROCEDURE

PROCEDURE EEPROM_ReadByte(address) RETURNS byte
    IF address > 0x3FF THEN
        RETURN 0xFF (address out of range)
    END IF

    CREATE command_array with 3 elements:
        command_array[0] = 0x03 (READ instruction)
        command_array[1] = upper 3 bits of address (A10-A8)
        command_array[2] = lower 8 bits of address (A7-A0)

    INITIALIZE data_byte = 0

    PULL CS line LOW
    SEND command_array (3 bytes) over SPI
    READ data_byte from SPI
    PULL CS line HIGH

    RETURN data_byte
END PROCEDURE

DECLARE keypad_map as array:
    ['1', '2', '3',
     '4', '5', '6', 
     '7', '8', '9',
     '*', '0', '#']

FUNCTION read_keypad() RETURNS character
    FOR each row from 0 to ROWS-1:
        // Activate current row, deactivate others
        FOR each setup_row from 0 to ROWS-1:
            IF setup_row equals current row THEN
                SET row pin to ACTIVE_LEVEL
            ELSE
                SET row pin to INACTIVE_LEVEL
            END IF
        END FOR
        
        // Check each column for button press
        FOR each col from 0 to COLS-1:
            IF column pin reads LOW (button pressed) THEN
                CALCULATE key_index = row * COLS + col
                RETURN keypad_map[key_index]
            END IF
        END FOR
    END FOR
    
    RETURN null character (no key pressed)
END FUNCTION

PROCEDURE ST7565_WriteCommand(command_byte)
    SET DC pin to LOW (command mode)
    SET CS pin to LOW (select device)
    SEND command_byte over SPI
    SET CS pin to HIGH (deselect device)
END PROCEDURE

PROCEDURE ST7565_WriteData(data_byte)
    SET DC pin to HIGH (data mode)
    SET CS pin to LOW (select device)
    SEND data_byte over SPI
    SET CS pin to HIGH (deselect device)
END PROCEDURE

PROCEDURE ST7565_Init()
    CALL ST7565_Reset() to toggle RST pin
    WAIT 50 milliseconds after reset
    
    // Send initialization commands
    SEND command 0xAE (Display OFF)
    SEND command 0xA2 (Set bias to 1/9)
    SEND command 0xA0 (ADC normal direction)
    SEND command 0xC8 (COM output reverse direction)
    SEND command 0x22 (Set resistor ratio)
    SEND command 0x2F (Power control: all circuits ON)
    SEND command 0x40 (Set start line to 0)
    SEND command 0xAF (Display ON)
    
    // Optional contrast setting
    SEND command (0x20 OR 0x06) to set resistor ratio for contrast
END PROCEDURE

PROCEDURE read_temperature_and_humidity(i2c_handle, temperature_pointer, humidity_pointer)
    DECLARE command_byte = 0xFD
    DECLARE sensor_address = 0x45
    
    // Send measurement command
    CALL i2c_write(i2c_handle, sensor_address shifted left by 1, command_byte, 1 byte, 100ms timeout)
    WAIT 30 milliseconds for measurement completion
    
    // Read measurement data (6 bytes total)
    DECLARE receive_buffer[6]
    CALL i2c_read(i2c_handle, sensor_address shifted left by 1, receive_buffer, 6 bytes, 100ms timeout)
    
    // Parse temperature data
    CALCULATE temperature_raw = receive_buffer[0] * 256 + receive_buffer[1]
    SET temperature_checksum = receive_buffer[2]
    
    // Parse humidity data  
    CALCULATE humidity_raw = receive_buffer[3] * 256 + receive_buffer[4]
    SET humidity_checksum = receive_buffer[5]
    
    // Handle checksum error case
    IF temperature_checksum equals 0 AND humidity_checksum equals 0 THEN
        SET humidity_pointer value to 0.0
    END IF
    
    // Convert raw values to actual temperature and humidity
    CALCULATE temperature_celsius = -45 + (175 * (temperature_raw / 65535.0))
    CALCULATE humidity_percent = -6 + (125 * (humidity_raw / 65535.0))
    
    // Clamp humidity to valid range [0, 100]
    IF humidity_percent > 100.0 THEN
        SET humidity_percent = 100.0
    END IF
    IF humidity_percent < 0.0 THEN
        SET humidity_percent = 0.0
    END IF
    
    // Store results
    SET temperature_pointer value to temperature_celsius
    SET humidity_pointer value to humidity_percent
END PROCEDURE