The address does not roll over to the next line. Your mileage may vary. Access Warning You do daasheet have the correct permissions to perform this operation. We can make character fonts as we wish. There are many displays out there based on KS or compatible display controller.
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Unlike a character LCD which can only display alphanumeric characters, a graphical LCD can display images, fonts and other structures. In comparison with character LCD, it can display anything on the screen provided by the user. Character LCD only displays the alphanumerical characters. The user can create images, fonts and other structures and display on them. KS is a dot matrix display controller from Samsung with 64 channel output. To generate timing signals for these two controllers, there is a common driver KS It has 8 data lines, 6 control lines and 6 power and display related pins.
Pin descriptions are given below. We use these pins to transfer the data to the display RAM. Power pins 1 and 2 pins are Vdd and Vss pins. Connect these pins to 5V and ground respectively. The pin 18 is the output of a negative voltage generator. By using a potentiometer, we can generate the required operating voltage by feeding the negative voltage to the Vo pin. We can vary Vo to change the contrast of the display.
The 19 and 20 pins are Anode and cathode of backlit LED, limit the current through it by putting a resistor in the line. We can use a pot if you need to vary this too. RST is the reset pin, it is used to reset the entire display content by clearing whole of the display RAM. One of the important consideration while clocking is, always give at least 1 microsecond delay after every instruction or data transfer. This parameter will be defined as Ecycle in the datasheet of the module. For JHD, the Ecycle value is 1us.
KS is a 64 channel common driver which generates timing signals to control the other two KS segment drivers. There is also a negative voltage generator which outputs the negative voltage through Vee pin. In some display modules, this section may not be present. So we will need to generate the negative voltage from outside. In some GLCD displays, the segment and common drivers used will be made by different manufacturer, but they will be compatible with KS controllers.
There are 8 pages in each half which is controlled by each KS controller. One page one row contains 64 columns of 8 rows. Whenever we transfer the data, we first selects the half by CS bits, then page address X and then the Y address.
The byte will be transferred as a 1 bit wide strip and will be stored in display RAM location. We can summarise this process as follows. We will be leaving first two columns, 8th column and last row of the page for spacing. Below image explains how the fonts are created in graphic LCDs.
In order to display this, we need to transfer following bytes to the first page of the display by selecting left controller CS1 in Y address from 0 to 7: 0x00, 0x00, 0x7F, 0x09, 0x09,0x09,0x06,0x KS Instructions There are seven instructions available in KS controller and are given in the below table.
The above table lists different instructions available for KS controller. We will be discussing each of the instructions and implementation in the next part of this article. We have used a 1K resistor to limit the current to the backlit LED. We will discuss the different instructions and firmware implementation in next part of this article.
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KS0108 Graphic LCD Interfacing with PIC18F4550-Part 1