UM0239 datasheet(24/44 Pages) STMICROELECTRONICS

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Getting started

UM0239

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4.6

Reading/Writing Control Register parameters

Figure 11 summarizes the Control Register reading/writing procedures with the PLM Demo

Board.

Figure 11.

Control register writing/reading procedures

On the Control Register window, click Write CTRL Register to transmit the 24- or 48-bit

Control Register string to the ST7540 PLM Demo Board.

Click Read CTRL Register to read the contents of the Control Register string. This displays

the Read Control Register dialog box shown in Figure 12.

Figure 12.

Read CTRL Register dialog box

If no communication issues occur, the Read Control Register string (which is similar to the

Write Control Register string) displays the content of the ST7540 Control Register. Note that

24 or 48 bits are read, depending on parameters Extended Control Register (Bit 21) and

Header Recognition (Bit 18).

Click the Read button in the Read Control Register dialog box to perform a new reading of

Control Register string values. Click the Update Ctrl Panel button to update the Control

Control Register dialog box.

ST7540 CR WRITING/READING PROCEDURES

WRITING

READING

Extended register Enable?

(CR Bit 21 equal to 1)?

yes

Write 24 bits

no extended

functions

available

Write 48 bits

extended

functions

available

Last 24 bits are significant

(not all “0” or all “1”)

yes

Get only

first 24 bits

Get all 48

bits

Read always 48 bits from ST7540

ST7540 READ CR WINDOW

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