??? 07/31/08 04:32 Read: times |
#157151 - Additional specs. Can you do it? Responding to: ???'s previous message |
All good comments: The outputs will run small relays, so probably an AND gate would suffice to bring the power up to be able to hold a relay open (or closed as the case may be with the coil wattage of a relay at issue).
Ok.. we were understadut the Chip we originally referenced had 16 inputs , in the case that it doesn't and the easiest to get for the least money are 12, then us 12,its ok. This is the first pass, we plan more for later projects and this was just to get us started. (we really need a shell program that we can modify ourselves in the future. Its too much for us to reinvent something you guys probably use everyday. ). INPUTS: We don't know what the chip we originally asked about could do for inputs, our old knowledge seems to say 0-5v input is safe and easier to work with. But you can tell us what they can go up to. We can always , as said , divide it down to what we need. (or up if needed). Bits of resolution can be small since its only 2 significant digits we are worried about. 3 bits is plenty and since always positive you don't need an extra bit for plus/minus. (If sensor input is high "enough" impedance, doesn't that mean you don't need buffering? Low impedance creates alot of problems with each stage looking back into the last stage in this case the sensor , as we understand it. ) Just say input voltage range is 0-5 since we can fix it to that in any case. The sensors will be various but one example is a temperature sensor. Ok use any sort you want.. bubble sort is just one example to get us started. After we work that out and make it work with our equipment then we'll be ready to pursue other logic schemes that are more robust and flexible. One commentor said that spikes could ocur which would be almost impossible with a temp sensor, but one could always use a low pass filter on the input if worried about that. Thanks for your comments. Now , can you do it? ========================================================== Having 16 outputs that should be either 0V or 5V is easy. It is just a digital output from a chip supplied from 5V. Possibly buffered by a buffer chip or transistors if you need more power. But the need for buffering can't be known, unless you tell what the outputs are expected to be used for. That affects their need for short-circuit-protection, or protection for over- or undervolages, ... Having 16 analog inputs is something else. Most microcontrollers have 1, 2, 4 or maybe 8 analog inputs. Some may even have 12, but the availability of a microcontroller with 16 ADC inputs is quite low. To my knowledge, Silabs are the only ones. But it isn't enough to specify that you need 16 ADC, you also need to specify number of bits of resolution, and the voltage range they should measure. Is it between 0 and 5V, as your example seem to imply? Not only do you need to specify the input voltage range, but also what type of sensors you will connect, so it can be known if they are extremely high-impedive (requiring analog buffering) or if there may be a need for other adaptations. This bsort is the "how" for the this first pass. Another thing. I don't know how many times you write about bubble sort. Are you 100% sure that you need/want bubble sort? A customer normally only specify what should be done, not how, unless the "how" is important. How do you know that you need a bubble sort, and not insertion sort, quicksort, radix sort, heapsort, ...? |