Display NHD-C12864WO-B1TFH#-M contrast options.
I notice that the Newhaven datasheet shows a resistor network between VR, VOUT, and V0.
The Newhaven display uses the ST7565P controller. According to the datasheet for this controller, there should be operating modes that do not require any connection to VR. I should be able to use the internal regulator and set the contrast using a series of commands to the unit.
Am I missing something? Has the internal contrast control logic been disabled in the Newhaven unit? Is it the only available option to redesign my circuit so as to use an external resistor network to set VR?
The main mechanism for controlling and adjusting the contrast is through the external resistor network as labeled on the wiring diagram.
The internal contrast control can be used to tune the contrast such as the electronic volume command, but this may not yield significant change in the contrast levels when compared to utilizing a potentiometer in the circuit for this particular display.
As you pointed out, the ‘IRS’ pin for selecting the voltage level adjustment is not brought out to the user, however it may still be possible to apply the necessary voltage externally to VR while excluding adding the external resistor network, and it may be beneficial to test this in your design.
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