8051 Projects and 8051 Microcontroller Projects

ADC is an electronic device which converts analog signals into its corresponding digital signal. This article demonstrates the principle, operation and interfacing  of 8-bit serial ADC0831 with 8051 microcontroller.

ADC0831 is an 8 pin IC with 8-bit serial data output (for more detail about ADC0831 refer to Interfacing ADC0831 with ATmega16). To receive the output from ADC high to low pulse is given at CS (chip select) pin of ADC form controller. ADC requires delay of two clock pulses before starting data conversion. At the second clock cycle, ADC sends a ‘0’ bit to the controller which indicates that the upcoming bits are the data bits.

ADC needs eight clock pulses to send 8-bit digital output. This digital data is received bit by bit and stored in a variable.  The data is converted to its corresponding ASCII value and sent to LCD for display. The connections of LCD with microcontroller are shown in circuit diagram. The analog signals are generated by at a variable resistance (preset) which is connected to input pin of ADC0831.

The commonly used 16x2 LCD can also display custom made characters besides numbers, alphabets & special characters. Any character can be made to appear  on a 5x8 pixel matrix element without knowledge of its ASCII value. The idea explained here demonstrates the principle and operation of a simple LCD custom character display using 8051 microcontroller (AT89C51). When the ASCII code for any character, say ‘A’, is sent to be displayed on LCD module, the module's controller looks up the appropriate 5x8-pixel pattern in ROM (read-only memory) and displays that pattern on the LCD. There are 8 symbol locations where a custom character can be stored as shown in the following right table. These locations will have a particular bitmap layout corresponding to the custom character. To display an arrow sign, the bitmap values are mapped to a base address location, say 64 (ASCII code 0).