Monthly Archives: October 2010


Serial LCD Module using PIC16F88

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A varieties of serial LCDs from different manufacturers are available in the market. But if you are good at PIC programming you can make one by yourself. The most popular and low cost LCDs for embedded projects are HD44780 based character LCD modules. They are parallel LCDs because they recieve display data from microcontrollers in parallel format. Their interface require at least 6 I/O pins of a microcontroller. By including an additional microcontroller to your HD44780 LCD module you can convert it to a serial LCD. The idea is very simple. The extra controller will receive the display data from

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Experimental board for ATTiny2313

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This is an experimental board for ATTiny2313 microcontroller that provides a 10-pin connector for in-circuit serial programming, and other header pins to access I/O pins. The AT2313 microcontroller runs on an external 10Mhz crystal. The board has a push button reset switch for resetting the microcontroller. The onboard regulator provides a +5V DC to the microcontroller. The board is also featured with a DB9 connector to communicate with a PC through RS232 port. The TTL to RS232 level translation is achieved through a MAX232 chip. The circuit for this board is very simple to build, and the PCB layout is

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A simple idea of making a digitally controlled variable power supply.

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A variable power supply is a very useful tool for designing and testing electronics circuit. There are varieties of adjustable regulator IC’s available to generate a variable DC power supply. They normally use a two-resistor feedback network at the output to control the output voltage. If one of the resistor is replaced by a potentiometer, the output voltage can be easily adjusted as required. LM350 is one of such adjustable regulators that is capable of supplying in excess of 3A over a 1.2V to 33V output range, and is very easy to use. It requires only 2 external resistors to

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A simple parallel port programmer for ATMEL’s 20 pin microcontrollers

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We hardly look for a programmer like this now a days because parallel ports are gone in modern desktop computers and laptops. However, if you still have got your old computer somewhere at a corner of your house, this programmer circuit might be useful to you. This programmer supports AT89C1051, AT89C2051, and AT89C4051 microcontrollers from ATMEL and uses an LPT (Line Print Terminal) port to communicate with the host computer. The programming software is free to download for non-commercial or personal use. You can download both DOS and Windows versions of the programming software. Circuit diagram of the programmer (Source:

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ADC channels in PIC16F688

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The PIC16F688 microcontroller has a built-in 10-bit ADC with eight input channels. The eight channels are available at RA0, RA1, RA2, RA4, RC0, RC1, RC2, and RC3. They have alternate labels, AN0-AN7, for this function, and are multiplexed into a single sample and Hold circuit. The output of the sample and hold is connected to the input of the A/D converter. The A/D conversion is successive approximation based and the 10-bit result is stored  into the ADC result registers ADRESH (A/D Result Higher byte) and ADRESL (A/D Result Lower byte). Each of these registers is 8-bit. Pin diagram of the PIC16F688 microcontroller

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