STLED524 datasheet(35/72 Pages) STMICROELECTRONICS

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STLED524

Detailed description

4.7.3

Scroll possibilities

The display content scroll is enabled, if SCRLEN bit in the display visual control register is

set to 1. If this bit is 1 and new value of DISP bits (DISP1 and DISP2) is written through SPI,

scroll operation starts. The type of scroll operation is defined by the content of scroll control

registers.

Blank rows or columns can be inserted between two patterns during the scroll operation.

These blank rows/columns are inserted by the logic of the driver automatically, so they are

not part of patterns. The number of blank rows/columns can be set by the scroll control

visual control register is set to 1.

Table 44 contains all possible types of scroll operations. X → Y expression means that the

display content is X and when the scroll operation is over, it is Y. All possibilities listed below

are valid for all directions. DISP (act) is the value of DISP bits. DISP (new) is the new value

of these bits written through SPI.

There are two interrupts related to the scroll operation. These are EOSCR (end of scroll)

and step. This interrupt is generated at the end of scroll operation (when the new pattern is

visible). The end of step interrupt is generated after each scroll step. It is useful to read the

scroll step register value, when this interrupt is detected. It gives the microcontroller

information about the position of the pattern on the display.

If WAITEN bit in the display visual control register is set, the end of scroll interrupt is delayed

by the wait time given by the value of the scroll control 3 register.

Columns from 20 to 23 can be locked during the scroll operation. These locked columns do

not move during scroll operation. Their content is always stored in pattern 1 register.

DISPSIZE bit, in the display visual control register, has to be set to 1 to lock columns from

20 to 23. If this bit is set to 0, columns from 20 to 23 scroll in the same way as the rest of the

display. If DISPSIZE bit is set to 1, the number of scroll steps is limited to 20 in horizontal

direction (if no blank column is inserted). The number of steps in vertical direction is not

affected.

Table 46. List of all scroll operations

DISP (act)

DISP (new)

BRCEN

→ B

→ P1

→ P2

→ B

→ P1 (rotation)

→ P2

→ B

→ P1

→ P2 (rotation)

→ Brc →B

→ Brc → P1

→ Brc → P2

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