LCD Driver IC:
LCD driver IC is the main part of the display imaging system, integrated resistors, regulators, comparators and power transistors and other components, including LCD modules and display subsystems, responsible for driving the display and control the drive current and other functions, divided into two methods of static drive and dynamic drive.
Driver IC Function Features:
Internal self-built 256khzrc oscillator, external 32.768khz crystal or 256khz frequency input, internal 32 × 4bit display. ram can choose 1/2 or 1/3 bias, and 1/2, 1/3 or 1/4. end serial interface duty cycle LCD built-in lcd drive signal source, internal time reference frequency, available command control operation, buzzer drive data mode and command mode instructions, with shutdown instructions to reduce power consumption, r/w address auto-accumulation internal time base generator and wdt. Watchdog timer, 3 data storage modes time base or wdt overflow output, vlcd pin used to adjust the operating voltage.
Driver IC:
(1 ) Ram Static Display: Structured as 32 x 4 bits, storing the displayed data. ram content is directly mapped to the driver content. data in ram can be read, write and read-modify--write commands to access.
(2) System oscillator: The cms1621 system clock is used to generate the clock for the time base/wdt circuit, the LCD driver clock, and the beep frequency. The clock can come from an on-chip, oscillator (256khz), crystal oscillator (32.768khz) or an external 256khz clock set by s/w.
(3 Time Base and Watchdog Timer:The time base generator is composed of an 8-stage incremental counter and is used to design and produce an accurate time base. The watchdog timer (wdt) consists of an 8-stage time base generator and a 2-stage incremental counter. It is used to stop the main controller or other subsystems in abnormal states (unknown or undesired jumps, execution errors, etc.).
(4) The buzzer output is provided in the cms1 621 as a simple buzzer oscillator. The beep oscillator can provide - pairs of beep drive signals bz and bz,which are used to generate a simple beep. The tone4k and tone2k commands can be executed to generate two beep frequencies, the tone4k and tone2k commands set the beep frequency to 4khz and 2khz respectively, and the beep drive signal can be called tone on or tone off to turn on or off.
(5) LCD driver IC cms1621 is a 128(32×4) dot matrix lcd driver, it can drive 1/2 or 1/3 bias, 2, 3 or 4 com end lcd display, this feature makes cms1621 suitable for many kinds of lcd display.
(6) Command Format: cms1621 can be set by s/w. There are two modes of commands for setting cms1621 and transmitting lcd display data, namely command mode and data mode. The setting of cms1621 is called command mode, where id is 100, and consists of system setting command, system frequency selection command, lcd structure command beep frequency selection command and operation command.
(7) Interface cms1621 has 4 lines need to interface. cs initializes the serial interface circuit and connects the communication end in between the main controller. CS is 1, the data and command between the main controller and cms1621 are disabled and initialized.
