- Sat Jul 15, 2006 6:24 am
#15882
Hi,
I utilized a MAX232 (or compatible) for negative voltage generation of a GDM12864M, since I could get neither HT7660 nor LM2660 in my city.
If you won't use hardware flow control in your microcontroller system, you may be able to utilize unused 'another' channel of a MAX232 as follows.
1. Tie T2IN (unused channel) to Vdd with a 10k resistor. That results -9V output from T2OUT.
2. Tie center pin of a 50k VR to V0 (contrast adjust) of the GDM12864M.
3. Tie other two pins of the VR to T2OUT and Vss, respectively.
4. Rotate the VR closest to Vss and turn your system on.
5. Turn the VR oppsosite direction until your preferred contrast.
Note that V0 never go under -8.8V in 5V system, according to the datasheet.
I utilized a MAX232 (or compatible) for negative voltage generation of a GDM12864M, since I could get neither HT7660 nor LM2660 in my city.
If you won't use hardware flow control in your microcontroller system, you may be able to utilize unused 'another' channel of a MAX232 as follows.
1. Tie T2IN (unused channel) to Vdd with a 10k resistor. That results -9V output from T2OUT.
2. Tie center pin of a 50k VR to V0 (contrast adjust) of the GDM12864M.
3. Tie other two pins of the VR to T2OUT and Vss, respectively.
4. Rotate the VR closest to Vss and turn your system on.
5. Turn the VR oppsosite direction until your preferred contrast.
Note that V0 never go under -8.8V in 5V system, according to the datasheet.