HM17CM256
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When using partial display function, the display duty can be selected among 1/17, 1/26, 1/32, 1/38,
1/47, 1/66, 1/77 by setting the LCD duty set command.
The display states such as LCD driving bias ratio, LCD Driving voltage, electric volume setting
value, boosting coefficient should be optimized to the selected LCD and display duty.
(29) DISCHARGE CIRCUIT
The discharge circuit of voltage(V
LCD
, V
1
~V
4
) stabilization capacitor is built in the HM17CM256.
To discharge the capacitors, set the DIS register to “1” or set the RES terminal to “0”. When built-
in power supply circuit is used, built-in power supply circuit should be disabled before discharging of
the capacitor is executed. When external power supply(V
LCD
, V
1
~V
4
, V
OUT
) is used, external power
supply should be turned off before discharging of the capacitor is executed. Do not turn on the
internal power supply and external power supply (V
LCD
, V
1
~V
4
, V
OUT
) during discharging is executed.
(30) RESET CIRCUIT
HM17CM256 is initialized as following description when RES terminal is set to “L”.
INITIAL SETTING CONDITION (default setting)
1. display RAM
:unknown
2. X address
:00
H
set
3. Y address
:00
H
set
4. display start line
:1 line value 0
H
5. display ON/OFF
:display OFF
6. positive/negative
:positive
7. display duty ratio
:1/82
8. n line inversion
:n inversion disable
9. COM shift direction
:COM
0
→
COM
79
, COMI
0
, COMI
1
10. increment mode
:increment OFF
11. REF mode
:positive
12. data SWAP mode
:OFF
13. electric volume
:(0, 0, 0, 0, 0, 0, 0)
14. power circuit
:OFF
15. display mode :gradation display mode
16. bias ratio
:1/10 bias
17. gradation palette 0
:(0, 0, 0, 0, 0)
18. gradation palette 1
:(0, 0, 1, 0, 1)
19. gradation palette 2
:(0, 1, 0, 1, 0)
20. gradation palette 3
:(0, 1, 1, 1, 0)
21. gradation palette 4
:(1, 0, 0, 0, 1)
22. gradation palette 5
:(1, 0, 1, 0, 1)
23. gradation palette 6
:(1, 1, 0, 1, 0)
24. gradation palette 7
:(1, 1, 1, 1, 1)
25. gradation mode
:variable mode
26. GLSB
:"0"
27. RAM data length
:8 bit mode
28. discharge register
:"0"
Usually RES terminal is connected reset terminal of CPU, so that the chip can be initialized
simultaneously with CPU. HM17CM256 should be initialized when the power is on.