STM32WB55CC datasheet(45/165 Pages) STMICROELECTRONICS

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DS11929 Rev 3

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STM32WB55xx

Functional overview

3.18

Liquid crystal display controller (LCD)

All device embed an LCD controller with the following characteristics:

•

Highly flexible frame rate control.

•

Supports Static, 1/2, 1/3, 1/4 and 1/8 duty.

•

Supports Static, 1/2, 1/3 and 1/4 bias.

•

Double buffered memory allows data in LCD_RAM registers to be updated at any time

by the application firmware without affecting the integrity of the data displayed.

–

LCD data RAM of up to 16 x 32-bit registers which contain pixel information

(active/inactive)

•

Software selectable LCD output voltage (contrast) from VLCDmin to VLCDmax.

•

No need for external analog components:

–

A step-up converter is embedded to generate an internal VLCD voltage higher

than VDD (up to 3.6 V if VDD > 2.0 V)

–

Software selection between external and internal VLCD voltage source. In case of

an external source, the internal boost circuit is disabled to reduce power

consumption

–

A resistive network is embedded to generate intermediate VLCD voltages

–

The structure of the resistive network is configurable by software to adapt the

power consumption to match the capacitive charge required by the LCD panel

–

Integrated voltage output buffers for higher LCD driving capability.

•

The contrast can be adjusted using two different methods:

–

When using the internal step-up converter, the software can adjust VLCD between

VLCDmin and VLCDmax

–

Programmable dead time (up to eight phase periods) between frames.

•

Full support of low-power modes: the LCD controller can be displayed in Sleep,

Low-power run, Low-power sleep and Stop modes, or can be fully disabled to reduce

power consumption.

•

Built in phase inversion for reduced power consumption and EMI (electromagnetic

interference).

•

Start of frame interrupt to synchronize the software when updating the LCD data RAM.

•

Blink capability:

–

1, 2, 3, 4, 8 or all pixels can be programmed to blink at a configurable frequency

–

Software adjustable blink frequency to achieve around 0.5 Hz, 1 Hz, 2 Hz or 4 Hz.

Used LCD segment and common pins should be configured as GPIO alternate functions

and unused segment and common pins can be used for general purpose I/O or for another

peripheral alternate function.

Note:

When the LCD relies on the internal step-up converter, the VLCD pin should be connected

to VSS with a capacitor. Its typical value is 1 μF.

3.19

True random number generator (RNG)

All devices embed a true RNG that delivers 32-bit random numbers generated by an

integrated analog circuit.

STM32WB55CC Datasheet(PDF) 45 Page - STMicroelectronics

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