Liquid crystal display controller (LCD) RM0351
782/1830 DocID024597 Rev 5
Bits 9:7 DEAD[2:0]: Dead time duration
These bits are written by software to configure the length of the dead time between frames.
During the dead time the COM and SEG voltage levels are held at 0 V to reduce the contrast
without modifying the frame rate.
000: No dead time
001: 1 phase period dead time
010: 2 phase period dead time
......
111: 7 phase period dead time
Bits 6:4 PON[2:0]: Pulse ON duration
These bits are written by software to define the pulse duration in terms of ck_ps pulses. A short
pulse will lead to lower power consumption, but displays with high internal resistance may
need a longer pulse to achieve satisfactory contrast.
Note that the pulse will never be longer than one half prescaled LCD clock period.
000: 0
001: 1/ck_ps
010: 2/ck_ps
011: 3/ck_ps
100: 4/ck_ps
101: 5/ck_ps
110: 6/ck_ps
111: 7/ck_ps
PON duration example with LCDCLK = 32.768 kHz and PS=0x03:
000: 0 µs
001: 244 µs
010: 488 µs
011: 782 µs
100: 976 µs
101: 1.22 ms
110: 1.46 ms
111: 1.71 ms
Bit 3 UDDIE: Update display done interrupt enable
This bit is set and cleared by software.
0: LCD Update Display Done interrupt disabled
1: LCD Update Display Done interrupt enabled
Bit 2 Reserved, must be kept at reset value
Bit 1 SOFIE: Start of frame interrupt enable
This bit is set and cleared by software.
0: LCD Start of Frame interrupt disabled
1: LCD Start of Frame interrupt enabled
Bit 0 HD: High drive enable
This bit is written by software to enable a low resistance divider. Displays with high internal
resistance may need a longer drive time to achieve satisfactory contrast. This bit is useful in
this case if some additional power consumption can be tolerated.
0: Permanent high drive disabled
1: Permanent high drive enabled. When HD=1, then the PON bits have to be programmed
to 001.
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