![]() I'm not sure if I have missed something, or not understanding the circuit correctly, maybe both! I have attempted to use a TLC7524CN DAC, and LM358, but after reading the datasheet and searching the web, I have had no luck. Always.I am looking to use a binary switch to control a voltage on A0, then convert this to an integer to access an EEPROM address. That's why we don't just have 16 or 32 bit converters. If the converter has more bits, the worst case conversion time gets longer. So a 10-bit converter will take 10 steps in the worst case. In fact, in the worst case the number of steps required will be the number of bits in the resolution of the converter. This will gradually converge on the target value. The key is to change the guess each time by decreasing powers or 2. That's just over the target: down for the next guess of 410 (2.00 v). Up a bit more for the next guess: 412 (2.01 v). Now it's too big so the next guess has to be lower: 416 which is 2.03 v. So the next guess will be larger: 448 which is 2.19 v. The next guess will be 384 which converts to 1.88 v which is still less than the 2 v target. That converts to 1.25 v which is less than the 2 v input. A straightforward approach is to use a binary search technique: make the next guess 256. That means that the next guess needs to be lower. That converts to 2.5 v which is greater than the input (2 v). Let's use 2 volts from above as the input signal with the 10-bit converter. Let's say we start at the mid-point of the conversion range. What's successive approximation? It's a way to incrementally find an answer by trying a guess, seeing how it works out, then adjusting the guess to get closer to the desired outcome. These are similar to the digital multiplexers we've seen in previous parts of this series, but work with analog signals rather than digital ones. The '328 has a 10-bit ADC, so it's resolution is 5 v / 1024 = 0.00488 v.Īlthough the '328 has a single ADC, it has an analog multiplexer providing 6 inputs, one of which can be read at a time. the less change each increase of 1 in the result indicates (0.195 v for an 8-bit ADC, 0.0000763 v for a 16-bit ADC). The more bits in the ADC result, the finer it's resolution, i.e. If it's a 16-bit ADC the result would be 26,214. converts to an 8 bit number) the result would be 102. ![]() ![]() For example, assume that we're measuring a signal between 0 and 5 v. If we measure that voltage we can get a sense of what the strength of the light is. As the strength of the light falling on the photocell changes, so does its resistance, and so does the voltage at the point between it and the other resistor. It's a light sensitive resistor that you use in series between Vcc and ground with another resistor. Measuring light using a photocell is a great example of this. The more bits we convert to, the better the approximation to the actual analog signal. If the analog signal is below half Vcc (2.5 volts for a 5 volt MCU) we could convert it to a low (aka 0), otherwise we could convert it to a high (aka 1). As a simplest case example, we could have a 1-bit analog to digital converter. This quantification involves converting the analog signal into a number with some number of bits. Digital electronics (which includes MCUs) can't directly work with analog voltages, so they need to quantify such voltages into digital values. That means that instead of the binary high and low logic levels, voltages vary smoothly. MCUs are typically used to interface with the real world, and that world is analog. ![]()
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