Here's a little test board for LCD's that I knocked up the other day, it has three sockets for Hitachi based LCD's (to match the three different styles I have), and provides three different options for contrast control, either PWM (as this board is configured), or a single turn preset, or a multiturn one.
The blue LCD is the 'normal' sized 2x16, the smaller 2x16 is the one we use in one of our products (as it fits in the case), and the third is a 2x8 LCD.
There's been talk recently of PWM contrast control, the two green/yellow ones use a value of 10 for the contrast, and the blue one uses a value of 50 (although that could probably do with increasing a little). The three spurious pads, and R5, are simply to provide a connection to the unused pin Rx4, which on PortA is open-drain so is avoided for the LCD - and R5 is a pull-up for RA4 if you need it for any reason.
The blue LCD is the 'normal' sized 2x16, the smaller 2x16 is the one we use in one of our products (as it fits in the case), and the third is a 2x8 LCD.
There's been talk recently of PWM contrast control, the two green/yellow ones use a value of 10 for the contrast, and the blue one uses a value of 50 (although that could probably do with increasing a little). The three spurious pads, and R5, are simply to provide a connection to the unused pin Rx4, which on PortA is open-drain so is avoided for the LCD - and R5 is a pull-up for RA4 if you need it for any reason.
