CY8C56LP datasheet(55/120 Pages) CYPRESS

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PRELIMINARY

PSoC® 5LP: CY8C56LP Family

Datasheet

Document Number: 001-84935 Rev. **

Page 55 of 120

8.7 LCD Direct Drive

The PSoC Liquid Crystal Display (LCD) driver system is a highly

configurable peripheral designed to allow PSoC to directly drive

a broad range of LCD glass. All voltages are generated on chip,

eliminating the need for external components. With a high

multiplex ratio of up to 1/16, the CY8C56LP family LCD driver

system can drive a maximum of 736 segments. The PSoC LCD

driver module was also designed with the conservative power

budget of portable devices in mind, enabling different LCD drive

modes and power down modes to conserve power.

PSoC Creator provides an LCD segment drive component. The

component wizard provides easy and flexible configuration of

LCD resources. You can specify pins for segments and

commons along with other options. The software configures the

device to meet the required specifications. This is possible

because of the programmability inherent to PSoC devices.

Key features of the PSoC LCD segment system are:

LCD panel direct driving

Type A (standard) and Type B (low power) waveform support

Wide operating voltage range support (2 V to 5 V) for LCD

panels

Static, 1/2, 1/3, 1/4, 1/5 bias voltage levels

Internal bias voltage generation through internal resistor ladder

Up to 62 total common and segment outputs

Up to 1/16 multiplex for a maximum of 16 backplane/common

outputs

Up to 62 front plane/segment outputs for direct drive

Drives up to 736 total segments (16 backplane x 46 front plane)

Up to 64 levels of software controlled contrast

Ability to move display data from memory buffer to LCD driver

through DMA (without CPU intervention)

Adjustable LCD refresh rate from 10 Hz to 150 Hz

Ability to invert LCD display for negative image

Three LCD driver drive modes, allowing power optimization

Figure 8-11. LCD System

8.7.1 LCD Segment Pin Driver

Each GPIO pin contains an LCD driver circuit. The LCD driver

buffers the appropriate output of the LCD DAC to directly drive

the glass of the LCD. A register setting determines whether the

pin is a common or segment. The pin’s LCD driver then selects

one of the six bias voltages to drive the I/O pin, as appropriate

for the display data.

8.7.2 Display Data Flow

The LCD segment driver system reads display data and

generates the proper output voltages to the LCD glass to

produce the desired image. Display data resides in a memory

buffer in the system SRAM. Each time you need to change the

common and segment driver voltages, the next set of pixel data

moves from the memory buffer into the Port Data Registers via

DMA.

8.7.3 UDB and LCD Segment Control

A UDB is configured to generate the global LCD control signals

and clocking. This set of signals is routed to each LCD pin driver

through a set of dedicated LCD global routing channels. In

addition to generating the global LCD control signals, the UDB

also produces a DMA request to initiate the transfer of the next

frame of LCD data.

8.7.4 LCD DAC

The LCD DAC generates the contrast control and bias voltage

for the LCD system. The LCD DAC produces up to five LCD drive

voltages plus ground, based on the selected bias ratio. The bias

voltages are driven out to GPIO pins on a dedicated LCD bias

bus, as required.

8.8 CapSense

The CapSense system provides a versatile and efficient means

for measuring capacitance in applications such as touch sense

buttons, sliders, proximity detection, etc. The CapSense system

uses a configuration of system resources, including a few

hardware functions primarily targeted for CapSense. Specific

resource usage is detailed in the CapSense component in PSoC

Creator.

A capacitive sensing method using a delta-sigma modulator

(CSD) is used. It provides capacitance sensing using a switched

capacitor technique with a delta-sigma modulator to convert the

sensing current to a digital code.

8.9 Temp Sensor

Die temperature is used to establish programming parameters

for writing flash. Die temperature is measured using a dedicated

sensor based on a forward biased transistor. The temperature

sensor has its own auxiliary ADC.

LCD Driver

Block

UDB

DMA

Display

RAM

LCD

DAC

Global

Clock

PHUB

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