7
Sound and LCD Contrast Controller (SLCC)
The contrast and on-board Speaker volume are software settable via the on-board Sound and LCD
Contrast Controller (SLCC).
Following is the description of the serial data strings that the SLCC accepts and returns. In the
description, XX or xx represent valid hexadecimal numbers in the range 00 to FF and YYYY or yyyy
represent valid hexadecimal words in the range 0000 to FFFF, and AA or aa represent a valid
hexadecimal address from 00 to 3F. The hexadecimal digits are and must be uppercase only.
Contrast
{CXX} Sets the contrast to the value XX (00 is darkest, FF is brightest).
Volume
{VXX} Sets the volume to the value XX (00 is low, FF is high).
Display
{D} Returns the current settings of the contrast and volume as {CxxVxx}.
EEPROM Write
{WAA,YYYY} Writes the 16 bit hexadecimal word YYYY to memory location AA.
Note:
Location 00 is the contrast setting and 01 is the volume setting so changing these values will
change the contrast and volume on reset. Locations 2 – 5 are not currently used but are reserved for
future use so should not be used in your application.
EEPROM Read
{RAA} Returns the 16 bit hexadecimal word from location AA as {Raa,yyyy}.
Upon receiving the last character (which is '}' ) of a valid string, the SLCC returns the valid string,
including the '{' and '}'. If an invalid string is sent, nothing happens and no string is returned. The SLCC
is case sensitive and will only accept capital letters for data.
The contrast and volume settings are stored in the serial EEPROM, and these values are applied on
power-up. The EEPROM is a non-volatile storage that does not lose its data on power loss or
disconnection.
