>> Deutsche Version
The PCF8577 from Philips is programmable via I²C-Bus. One circuit can drive up to 64 LCD segments in duplex drive mode or up to 32 LCD segments in direct drive mode. In direct drive mode you can switch between two memory banks. Up to four PCF8577 in duplex drive mode or up to eight PCF8577 in direct drive mode can be connected together on the I²C-Bus. This circuit can also be used for port expansion as it provides 32 output port pins. A datasheet can be downloaded from the homepage of Philips. There is also a PCF8577A which differs only in the slave address from the PCF8577.
A four digit LC-Display (seven segments display) which can be programmed via a serial RS232
interface is concerned. The LCD segments are controlled by the I²C LCD driver circuit PCF8577.
The I²C-Bus is provided from a microcontroller AT89C2051 via software. Display data is sent
via the serial RS232 interface to the microcontroller. There are four programming modes:
Binary mode: The display segments are determined by four bytes which are transmitted as eight hexadecimal nibbles. Herewith any segment combinations can be displayed.
Hexadecimal mode: Four hexadecimal figures can be displayed, including some special characters like decimal point or minus.
Decimal mode: Four decimal figures can be displayed, including some special characters like decimal point or minus.
Besides there are commands for display test and clear display. Instead of a fourth decimal point the LC-Display has a colon between the both middle digits.
The schematic and the software can be downloaded here:
Project files for hardware and software in ZIP format:
Serially controlled LC-Display V1.1
For the hardware the freeware version of Eagle 3.55 is required. It is available for free from CadSoft.
Schematic and component placement in GIF format:
Schematic of serially controlled LC-Display
Component placement of serially controlled LC-Display
Printed circuit board:
There is a professionally manufactured unpopulated printed circuit board available for this project, named SER_LCD.BRD
More information is available here: Printed circuit boards for WOE projects
If you are interested in a programmed microcontroller, please send an email including the project name.
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Here is a table with datasheets of diverse graphic LCDs, which can be downloaded.
· Information around vacuum fluorescent displays
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