This is not new Idea of interfacing LCD using two wires, but it can help in many situations when there is not enough of microcontroller pins. This example is based onHitachi 44780 Alphanumerical LCD. This circuit I provide is only to represent an idea but I think it should work also if soldered. We know, that to make LCD working you need at least
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6 (in 4 bit mode) wires to control. But what if you need as many pins as possible from your avr and still want to see results on LCD. Then you need to use serial LCD or make one. In this example you just need to convert serial data coming to LCD using shift register. I suggest using 74HC164. You need only two wires to push data to shift register and then give them to LCD using a‚ Ea‚ strobe signal. Atmegaa‚ s PC1 pin clocks shift register and PC0 is data line. Before you write to shift register clean it by sending a‚ 0a‚ in eight clock cycles. You can erase register with additional wire controlling register reset, but there would be 3 lines used. After register is cleared, send eight bits to register. First bit sent is always 1, as it is used to strobe LCD, second bit is Register Select, and then one bit is not used and then follows 4 bits as data and las bit is always 0 in order to make strobe E work correctly. You should see that in eight clock cycle last bit in shift register enables LCD with a‚ 1a‚ value in last bit. Then by sending 1 ³ to data line you enable LCD E pin. Resistor and Diode acts there as AND element. If only register Q7 signal is active, but data low, then LCD E pin is low. If data line is high but 74HC164 register Q7 pin is low, then diode pulls low this signal and LCD pin will be low. Only when both PC0 and shift register Q7 are high, ten LCD pin E is strobed. We aim to transmit more information by...
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The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
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The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
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This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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