HCMS-39X2 Datasheet, PDF (14/22 Pages) Agilent(Hewlett-Packard) – 3.3 V High Performance CMOS 5x7 AlphaNumeric Displays

Control Register Data Loading
Data is loaded into the Control
Register, MSB first, according to
the procedure shown in Table 1
and Figure 5. First, RS is brought
to logic high and then CE is
brought to logic low. Next, each
successive rising CLK edge will
shift in the data on the D_IN pin.
Finally, when 8 bits have been
loaded, the CE line is brought to
logic high. When CLK goes to
logic low, new data is copied into
the selected control word.
Loading data into the Control
Register takes place while the
previous control word configures
the display.
Control Word 0
Loading the Control Register with
D₇ = Logic low selects Control
Word 0 (see Table 2). Bits D₀ -D₃
adjust the display brightness by
pulse width modulating the LED
on time, while Bits D₄ -D₅ adjusts
the display brightness by
changing the peak pixel current.
Bit D₆ selects normal operation
or sleep mode.
Sleep mode (Control Word 0, bit
D₆ = Low) turns off the Internal
Display Oscillator and the LED
pixel drivers. This mode is used
when the IC needs to be powered
up, but does not need to be
active. Current draw in sleep
mode is nearly zero. Data in the
Dot Register and Control Words
are retained during sleep mode.
Control Word 1
Loading the Control Register with
D₇ = logic high selects Control
Word 1. This Control Word
performs two functions: serial/
simultaneous data out mode and
external oscillator prescale select
(see Table 2).
14