# Welcome

This documentation will guide you through the methods available in the Four Letter pHAT python library.

Four Letter pHAT is a Raspberry Pi add-on with four star displays.

- More information - https://shop.pimoroni.com/products/four-letter-phat
- GPIO Pinout - http://pinout.xyz/pinout/four_letter_phat
- Get the code - https://github.com/pimoroni/four-letter-phat
- Get help - http://forums.pimoroni.com/c/support

# At A Glance

> Alphanumeric 14 segment LED backpack display.

> `fourletterphat.``begin`()
> `fourletterphat.``clear`()
> `fourletterphat.``print_float`(value, decimal_digits=2, justify_right=True)
> `fourletterphat.``print_hex`(value, justify_right=True)
> `fourletterphat.``print_number_str`(value, justify_right=True)
> `fourletterphat.``print_str`(value, justify_right=True)
> `fourletterphat.``set_blink`(frequency)
> `fourletterphat.``set_brightness`(brightness)
> `fourletterphat.``set_decimal`(pos, decimal)
> `fourletterphat.``set_digit`(pos, digit, decimal=False)
> `fourletterphat.``set_digit_raw`(pos, bitmask)
> `fourletterphat.``set_led`(led, value)
> `fourletterphat.``show`()
> `fourletterphat.``write_display`()

# Set A Single Digit

`fourletterphat.``set_digit`(pos, digit, decimal=False)

  Set digit at position to provided value.

  Position should be a value of 0 to 3 with 0 being the left most digit on the display. Digit should be any ASCII value 32-127 (printable ASCII).

`fourletterphat.``set_digit_raw`(pos, bitmask)

  Set digit at position to raw bitmask value.

  Position should be a value of 0 to 3 with 0 being the left most digit on the display.

# Set A Decimal Point

`fourletterphat.``set_decimal`(pos, decimal)

  Turn decimal point on or off at provided position.

  Position should be a value 0 to 3 with 0 being the left most digit on the display. Decimal should be True to turn on the decimal point and False to turn it off.

# Print A Float

`fourletterphat.``print_float`(value, decimal_digits=2, justify_right=True)

  Print a numeric value to the display.

  If value is negative it will be printed with a leading minus sign. Decimal digits is the desired number of digits after the decimal point.

# Print Hexadecimal

`fourletterphat.``print_hex`(value, justify_right=True)

  Print a numeric value in hexadecimal.

  Value should be from 0 to FFFF.

# Print A String

`fourletterphat.``print_str`(value, justify_right=True)

  Print a 4 character long string of values to the display.

  Characters in the string should be any ASCII value 32 to 127 (printable ASCII).

# Print A Number String

`fourletterphat.``print_number_str`(value, justify_right=True)

  Print a 4 character long string of numeric values to the display.

  This function is similar to print_str but will interpret periods not as characters but as decimal points associated with the previous character.

# Blink The Display

`fourletterphat.``set_blink`(frequency)

  Blink display at specified frequency.

  Note that frequency must be a value allowed by the HT16K33, specifically one of:
    - HT16K33_BLINK_OFF,
    - HT16K33_BLINK_2HZ,
    - HT16K33_BLINK_1HZ, or
    - HT16K33_BLINK_HALFHZ.

# Set Brightness

`fourletterphat.``set_brightness`(brightness)

  Set brightness of entire display to specified value.

  Supports 16 levels, from 0 to 15.

# Clear The Display

`fourletterphat.``clear`()

  Clear contents of display buffer.

# Update The Display

Once you’ve made your changes, you’ll need to update the display.

`fourletterphat.``show`()

  Display buffer on display.