The PSB pin is hardwired to Vdd, which means that if you attempt to put it into serial mode by taking PSB to ground, you short your powersupply to ground. Gah.
Is it possible to adjust contrast without a pot? Can I run a PWM signal into V0?
QuoteThe PSB pin is hardwired to Vdd, which means that if you attempt to put it into serial mode by taking PSB to ground, you short your powersupply to ground. Gah.Are you sure it is hardwired (connected directly) to Vdd and not 'pulled-up' via a resistor?
QuoteIs it possible to adjust contrast without a pot? Can I run a PWM signal into V0?That may be a problem since most GLCDs require a negative voltage for the contrast pin.I just found this --> http://forum.arduino.cc/index.php?topic=22588.0 which may or may not be of some help.Here's another one --> http://www.bajdi.com/cheap-128x64-graphic-lcd-12864zw/ try a Google search for glcd psb pin.Don
Great minds think alike. Turns out that there was a jumper disguised as a resistor, shorting Vdd to PSB.
i have the same problem with such a display...do you remeber, which resistor caused to problem ?
Please describe what problem you have, and post a photo of the back of the display.
You may need to use a multimeter to check whether PSB is connected to R9. My guess is that PSB is connected to both R9 and R10, that the other side of R9 goes to +5V, and the other side of R10 goes to ground. So the display can be fixed in serial or parallel mode depending on which one is fitted, or can be selected via the PSB pin if neither is fitted. So if you want to use it in serial mode, you will have to unsolder R9.