The essential thing is to get the power, Vdd (+5V) and Vss (GND) right or you are likely to do some damage. I used a multimeter to trace pins back to the chips to work out their designations. The 'MGCS' display module has a 13 pin connector with 2mm pin spacing, a plug fitting this was hand-wired to a connector with 2.5mm pins suitable for standard Arduino jumper hook-up wires. Imayuki's example suggests a value of 680ohm to 1.5k, I expect this has an effect upon the LCD's contrast and could be replaced with a pot, but I haven't experimented with it as 1.2k gives reasonable results. It could equally well be connected to ground. Schematic showing connections from the MGCS μPD7228 LCD to an Arduino UNOĪccording to the datasheet, having a resistor (R1) from the reset pin to VLC5 just serves to reduce current consumption from the voltage divider supplying the LCD voltage references - if reset is held high no current flows, when low (LCD running) the Arduino acts as a current sink for the voltage divider. I can also envisage writing a module to create bar graphs etc. There is potential for creating any arbitrary 5×7 character, though they'd have to be written to the display as 5x bytes of column data rather than characters. The incomplete pixel field (gaps between character rows and columns) limit the use of the pixel addressing functions for plotting data pixels. The same memory pointer is used for both character and bit mode, so you can end up writing characters displaced from their character columns, ie written across the normal character boundaries - not very useful unless you wanted to create a super smooth scroll effect. Additionally, there is a bit mode where you can either write a byte for each of the 50 columns, or set/reset individual bits in each column. Columns of pixels are numbered from the left-hand address of 49, down to the right-hand address of 0 - hence they decrement addresses when they write from left to right (there is also a right-to-left entry mode if required). In character mode the chip fills those five bytes (well, seven bits of those bytes, the 8th being for a cursor line) from the inbuilt character ROM, and decrements the address pointer by 5. The chip's bit memory is mapped directly to individual pixels, so that each displayed character is displayed from 5 consecutive bytes of ram. The standard chips have a 5 by 7 pixel ASCII and Japanese (Katakana) character set, with a separate 8th underscore row for a cursor. Viewed from the front of the display (with the chips not visible), the master (0x00) is on the left and controls the first 10 characters of both lines, and the slave is on the right and drives the second two rows of ten characters. On the first board the slave was 0x01, on the second board it responded to 0x01 or 0x11. These are set up with hardwired addresses, the master is always 0x00. The controller consists of two μPD7228 chips, one acting as master, the second as slave.
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