PCF8545 datasheet(16/68 Pages) NXP

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NXP Semiconductors

PCF8545

Universal LCD driver for multiplex rates up to 1:8

7.1.8 Command: load-data-pointer

The load-data-pointer command defines the start address of the display RAM. The

data pointer is auto incremented after each RAM write. The size of the display RAM is

dependent on the current multiplex drive mode setting, see Table 18.

Bit

Symbol

Value

Description

7 to 6

fixed value

Multiplex drive mode 1:8

5 to 0

DP[5:0]

00 0000[1] to

10 0111

6-bit binary value of 0 to 39

Multiplex drive mode 1:6

5 to 0

DP[5:0]

00 0000[1] to

10 1001

6-bit binary value of 0 to 41

Multiplex drive mode 1:4

5 to 0

DP[5:0]

00 0000[1] to

10 1011

6-bit binary value of 0 to 43

Table 18. Load-data-pointer - load data pointer command bit description

[1]

Default value.

Remark: Data pointer values outside of the valid range are ignored and no RAM content

is transferred until a valid data pointer value is set.

Filling of the display RAM is described in Section 7.9.

7.1.9 Command: write-RAM-data

This command initiates the transfer of data to the display RAM. Data is written into

the address defined by the load-data-pointer command. RAM filling is described in

Section 7.9.

Bit

Symbol

Value

Description

7 to 0

D[7:0]

0000 0000 to

1111 1111

writing data byte-wise to RAM

Table 19. Write-RAM-data - write RAM data command bit description[1]

[1]

For this command to be effective bit RS[1:0] of the control byte has to be set logic 01, see Table 24page 36.

7.2 Start-up and shut-down

7.2.1 Reset and Power-On Reset (POR)

After a reset and at power-on the PCF8545 resets to starting conditions as follows:

1. The display is disabled.

2. All backplane outputs are set to VSS.

3. All segment outputs are set to VSS.

4. Selected drive mode is: 1:8 with 1⁄4 bias.

5. The data pointers are cleared (set logic 0).

6. RAM data is not initialized. Its content can be considered to be random.

PCF8545

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 2 — 4 October 2021

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