There is one slight drawback to our flashing LED program. Each instruction takes one clock cycle to complete. If we are using a 4MHz crystal, then each instruction will take 1/4MHz, or 1uS to complete. As we are using only 5 instructions, the LED will turn on then off in 5uS. This is far too fast for us to see, and it will appear that the LED is perma
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nently on. What we need to do is cause a delay between turning the LED on and turning the LED off. The principle of the delay is that we count down from a previously set number, and when it reaches zero, we stop counting. The zero value indicates the end of the delay, and we continue on our way through the program. So, the first thing we need to do is to define a constant to use as our counter. We will call this constant COUNT. Next, we need to decide how big a number to start counting from. Well, the largest number we can have is 255, or FFh in hex. Now, as we mentioned in the last tutorial, the equ instruction assigns a word to a register location. This means that whatever number we assign our COUNT, it will equal the contents of a register. If we try and assign the value FFh, we will get an error when we come to compile the program. This is because location FFh is reserved, and so we can`t access it. So, how do we assign an actual number Well, it takes a little bit of lateral thinking. If we assign our COUNT to the address 08h, for example, this will point to a general purpose register location. By default, the unused locations are set to FFh. Therefore, if COUNT points to 08h, it will have the value of FFh when we first switch on. But, We hear you cry, how do we set COUNT to a different number Well, all we do is move` a value to this location first. For example, if we wanted COUNT to have a value of 85h, we can`t say...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
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....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
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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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