pcf85162 NXP Semiconductors, pcf85162 Datasheet - Page 14

• Manufacturer Part Number: pcf85162
• Description: Universal Lcd Driver For Low Multiplex Rates
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF85162_1
Product data sheet
7.10 Display RAM
The display RAM is a static 32 × 4-bit RAM which stores LCD data. A logic 1 in the RAM
bit-map indicates the on-state of the corresponding LCD element; similarly, a logic 0
indicates the off-state. There is a one-to-one correspondence between the RAM
addresses and the segment outputs, and between the individual bits of a RAM word and
the backplane outputs. The display RAM bit map
correspond with the backplane outputs BP0 to BP3, and the columns 0 to 31 which
correspond with the segment outputs S0 to S31. In multiplexed LCD applications the
segment data of the first, second, third, and fourth row of the display RAM are
time-multiplexed with BP0, BP1, BP2, and BP3 respectively.
When display data is transmitted to the PCF85162, the display bytes received are stored
in the display RAM in accordance with the selected LCD drive mode. The data is stored as
it arrives and does not wait for an acknowledge cycle as with the commands. Depending
on the current multiplex drive mode, data is stored singularly, in pairs, triples, or
quadruples. To illustrate the filling order, an example of a 7-segment display showing all
drive modes is given in
other LCD types.
Fig 9.
•
In the static drive mode the same signal is carried by all four backplane outputs and
they can be connected in parallel for very high drive requirements.
display RAM rows/
backplane outputs
The display RAM bit map shows the direct relationship between the display RAM addresses and
the segment outputs and between the bits in a RAM word and the backplane outputs.
Display RAM bit map
rows
(BP)
0
1
2
3
Rev. 01 — 7 January 2010
Figure
0
1
10; the RAM filling organization depicted applies equally to
2
3
display RAM addresses/segment outputs (S)
4
Universal LCD driver for low multiplex rates
Figure 9
columns
shows the rows 0 to 3 which
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PCF85162
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© NXP B.V. 2010. All rights reserved.
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