PCA9620 Datasheet, PDF (42/71 Pages) NXP Semiconductors – Universal LCD driver for low multiplex rates

NXP Semiconductors
PCA9620
Universal LCD driver for low multiplex rates
The data pointer is automatically incremented in accordance with the chosen LCD
multiplex drive mode configuration. That is, after each byte is stored, the contents of the
data pointer are incremented
• by eight (static drive mode)
• by four (1:2 multiplex drive mode)
• by two (1:4 multiplex drive mode)
• by one or two (1:6 multiplex drive mode), see Figure 37 on page 45
• by one (1:8 multiplex drive mode)
If the data pointer reaches the end of the RAM row it is automatically wrapped around to
address 0. This means that it can be continuously written to or read from the display RAM.
The data pointer should always be set to an address where the remaining RAM is divisible
by eight because odd bits will be discarded (see Figure 32). This behavior is actually only
shown in static drive mode because of the fact that the 60 RAM cells can’t be divided by
eight without remainder.
If an I²C-bus data access is terminated early then the state of the data pointer is unknown.
The data pointer must then be re-written prior to further RAM accesses.
7.9.1.1 RAM filling in static drive mode
In the static drive mode the eight transmitted data bits are placed in eight successive
display RAM columns in row 0 (see Figure 31).
columns
display RAM columns/segment outputs (S)
rows
012 34 56 7
display RAM rows/
backplane outputs
0
b7
b6
b5
b4 b3
b2 b1
b0
(BP)
55 56 57 58 59
b7 b6 b5 b4 b3 b2 b1 b0
MSB
LSB
transmitted data byte
Fig 31. Display RAM filling order in static drive mode
013aaa263
In order to fill the whole RAM row, 8 bytes must be sent to the PCA9620, but the last 4 bits
from the last byte are discarded, and the data pointer is wrapped around to column 0 to
start a possible RAM content update (see Figure 32).
PCA9620
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 1 — 9 December 2010
© NXP B.V. 2010. All rights reserved.
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