PCE85133AUG All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2015. All rights reserved.
Product data sheet Rev. 2 — 22 July 2015 11 of 50
NXP Semiconductors
PCE85133AUG
Universal 80 × 4 LCD driver for low multiplex rates
In the case described in Table 10 the RAM has to be written entirely and BP2/S2, BP2/S5,
BP2/S8 etc. have to be connected to segments/elements on the display. This can be
achieved by a combination of writing and rewriting the RAM like follows:
• In the first write to the RAM, bits a7 to a0 are written.
• In the second write, bits b7 to b0 are written, overwriting bits a1 and a0 with bits b7
and b6.
• In the third write, bits c7 to c0 are written, overwriting bits b1 and b0 with bits c7 and
c6.
Depending on the method of writing to the RAM (standard or entire filling by rewriting),
some segments/elements remain unused or can be used, but it has to be considered in
the module layout process as well as in the driver software design.
6.3.3 Writing over the RAM address boundary
In all multiplex drive modes, depending on the setting of the data pointer, it is possible to
fill the RAM over the RAM address boundary. In this case, the additional bits are
discarded.
6.3.4 Output bank selector
The output bank selector (see Table 8) selects one of the four rows per display RAM
address for transfer to the display register. The actual row selected depends on the
selected LCD drive mode in operation and on the instant in the multiplex sequence.
• In 1:4 multiplex mode, all RAM addresses of row 0 are selected, these are followed by
the contents of row 1, 2, and then 3
• In 1:3 multiplex mode, rows 0, 1, and 2 are selected sequentially
• In 1:2 multiplex mode, rows 0 and 1 are selected
• In static mode, row 0 is selected
The PCE85133AUG includes a RAM bank switching feature in the static and 1:2 multiplex
drive modes. In the static drive mode, the bank-select command may request the contents
of row 2 to be selected for display instead of the contents of row 0. In the 1:2 multiplex
mode, the contents of rows 2 and 3 may be selected instead of rows 0 and 1. This gives
the provision for preparing display information in an alternative bank and to be able to
switch to it once it is assembled.
Table 10. Entire RAM filling by rewriting in 1:3 multiplex drive mode
Assumption: BP2/S2, BP2/S5, BP2/S8 etc. are connected to segments/elements on the display.
Display RAM
bits (rows)/
backplane
outputs (BPn)
Display RAM addresses (columns)/segment outputs (Sn)
0 1 2 3 4 5 6 7 8 9 :
0 a7 a4 a1/b7 b4 b1/c7 c4 c1/d7 d4 d1/e7 e4 :
1 a6 a3 a0/b6 b3 b0/c6 c3 c0/d6 d3 d0/e6 e3 :
2 a5 a2 b5 b2 c5 c2 d5 d2 e5 e2 :
3 ----------:
