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By Ryan Sheldon | ||
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Analog to Digital Conversion: |
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Converting Voltages to Numbers |
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Throughout the internet, you will see many topics on Analog to Digital Conversion. Here, we will explore A/D as it pertains to NCD devices. As our devices evolve, we will enhance this article to match the capabilities of newer devices. Currently, we support 3 kinds of Analog to Digital Converters. 8-Bit, 10-Bit, and 12-Bit. If you are not familiar with what an Analog to Digital Converter is, here I will explain it as it pertains to our devices. A/D conversion is the process of converting a voltage in the range of 0 to 5VDC into a number that can be processed by custom software that you develop. The higher the voltage, the higher the number. For the time being, there are a few limitations to the A/D converters we currently employ in our devices. Therefore, the following rules MUST be observed to prevent damage to the device: IMPORTANT A/D Converter Wiring Rules
NCD ProXR Series Controllers support 8-Bit, 10-Bit, and 12-Bit A/D conversion depending on the model of the controller. The ProXR command set is used to request a A/D value from the controller. This command used also depends on the model of the controller. You must always ask the controller for a A/D value. ProXR controllers do not spontaneously generate data. They are command driven ONLY. 8-Bit Analog to Digital Conversion means a voltage from 0-5 volts will be divided into 256 parts and be returned to the user as a value from 0-255. 8-Bit is the most popular choice, mainly because only a single byte of data is required to return the result. Of the three resolutions supported, this is the lowest resolution, but because only a single byte of data is returned, it is also the fastest to respond. 10-Bit Analog to Digital Conversion means a voltage from 0-5 volts will be divided into 1024 parts and be returned to the user as two values, which are recombined to make a single value from 0 to 1023. These two values are called Least Significant Byte and Most Significant Byte. Since two bytes are returned, this operation is slower than 8-Bit A/D. But 10-Bit is higher resolution, and can provide a more accurate voltage measurement. 12-Bit Analog to Digital Conversion means a voltage from 0-5 volts will be divided into 4096 parts and be returned to the user as two values, which are recombined to make a single value from 0 to 4095. These two values are called Least Significant Byte and Most Significant Byte. Since two bytes are returned, this operation is slower than 8-Bit A/D. But 12-Bit is higher resolution, and can provide a more accurate voltage measurement than 8 or 10-Bit A/D. When asking a controller for a 10-Bit or 12-Bit analog to digital conversion value, two bytes are returned as mentioned above. These two bytes, MSB and LSB (Most and Least Significant Bytes) are recombined to form a single number, which is your final A/D value. Using the formula below, you can EASILY convert any LSB and MSB data into a usable value by applying the following methodology:
That's really all there is to Analog to Digital Conversion. But the applications are limitless. A/D is often used to read light levels and temperature levels. You can easily activate relays when A/D limits are reached. If it gets too dark outside, a light can be triggered. If it gets too cold, a heater can be activated. It can also be used to detect audio levels in a room when connected to a microphone, or even be used to read switches, potentiometers, and analog joysticks. The applications are limitless, and surprisingly easy to integrate. Visit out Analog to Digital page for a complete listing of all boards currently available. |
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