1 00:00:04,860 --> 00:00:11,520 ‫Welcome to the temperature sensor interface demonstration on the art development board for this demonstration 2 00:00:11,760 --> 00:00:18,210 ‫we're using two four digit seven segment displays on the breadboard where each of the segment of the 3 00:00:18,210 --> 00:00:25,920 ‫7:7 displays are tied together through a 56 ohm resistor and then is fed back into the JMB PMA port 4 00:00:26,280 --> 00:00:28,580 ‫of the Arti development board. 5 00:00:28,590 --> 00:00:34,020 ‫We also have each of the digits selects for all eight digits on the 7:7 display are controlled through 6 00:00:34,110 --> 00:00:43,380 ‫eight different two and thirty four transistors with 470 ohm resistor connected to the base. 7 00:00:43,490 --> 00:00:49,080 ‫And these are controlled through the J.C p.m. on port of the Ardie development board. 8 00:00:49,380 --> 00:00:56,280 ‫And we also have our external temperature sensor that we have on a separate circuit board that is controlled 9 00:00:56,280 --> 00:01:01,500 ‫with we have a power in the ground coming in and we're feeding the output of the temperature sensor 10 00:01:01,830 --> 00:01:04,440 ‫into the 8:0 of the chip kit. 11 00:01:04,440 --> 00:01:07,830 ‫Slash Arduino port on the arm on board. 12 00:01:07,830 --> 00:01:13,830 ‫We also have reusing switches zero to determine whether recalculate or temperature and Fahrenheit or 13 00:01:13,970 --> 00:01:20,030 ‫Celsius and our switch 3 which enables or disables the temperature collection. 14 00:01:20,220 --> 00:01:27,750 ‫So in order to show you switch three to set to enable right now we have it enabled if I pull high will 15 00:01:27,750 --> 00:01:28,620 ‫disable it. 16 00:01:28,670 --> 00:01:31,240 ‫You'll see we have all zeros across the board and two eights. 17 00:01:31,320 --> 00:01:37,380 ‫That's because with the micro BLAYSE processor we have running in there our default values for the output 18 00:01:37,380 --> 00:01:45,810 ‫ports that we're writing to our sign and our degree symbol whether it's C or F they go to all ones. 19 00:01:45,810 --> 00:01:48,410 ‫So they all they show up here. 20 00:01:48,450 --> 00:01:50,520 ‫They go all of those excuse me they go to all zeros. 21 00:01:50,670 --> 00:01:53,760 ‫So we're going to be pulling on those and we're in display in eight. 22 00:01:53,790 --> 00:02:00,690 ‫So if I pull it back down will display the temperature which currently the sensor is reading a temperature 23 00:02:00,690 --> 00:02:05,550 ‫of fifty six point seven fifty six point five nine degrees Fahrenheit. 24 00:02:05,760 --> 00:02:09,930 ‫And if I switch my switch down it'll turn to Celsius. 25 00:02:09,930 --> 00:02:12,010 ‫Now you notice there's a little bit of a delay. 26 00:02:12,030 --> 00:02:17,580 ‫That's because in the software we have a delay after we take that reading we wait a half second and 27 00:02:17,580 --> 00:02:22,200 ‫then we take another temperature reading and then update the temperature display because temperatures 28 00:02:22,230 --> 00:02:26,340 ‫typically do not change fast enough within a half a second. 29 00:02:26,340 --> 00:02:31,500 ‫They don't change that fast so every half second is plenty enough you could probably make it slower 30 00:02:31,920 --> 00:02:37,050 ‫but in order to show you how this actually works so I'm going to switch to Fahrenheit again. 31 00:02:37,080 --> 00:02:40,090 ‫So you know this is a little bit of a delay that's because we just took a reading. 32 00:02:40,440 --> 00:02:44,870 ‫And when updates now at fifty seven point seventy five degrees Fahrenheit. 33 00:02:45,090 --> 00:02:51,090 ‫Now in order to verify this is actually working one you could have a thermometer and get a reading of 34 00:02:51,090 --> 00:02:56,670 ‫the temperature in your house the thermometer in my house says it's approximately 58 degrees. 35 00:02:56,670 --> 00:03:02,190 ‫So we're within one degree and that's exactly what the data sheet says on this part is that it's accurate 36 00:03:02,190 --> 00:03:04,070 ‫within two degrees. 37 00:03:04,080 --> 00:03:11,160 ‫So if you take and put your finger over the sensor and see we're at 59 degrees and once we get the reading 38 00:03:11,160 --> 00:03:12,430 ‫you should see it jump up. 39 00:03:12,450 --> 00:03:16,640 ‫That's because my hand is warmer than the sensor itself. 40 00:03:16,770 --> 00:03:22,300 ‫And so it jumped it up went from 58 to almost 67 10 degrees in one second. 41 00:03:22,500 --> 00:03:29,010 ‫And from here on out it's going to slowly creep up until eventually through thermodynamics the temperature 42 00:03:29,010 --> 00:03:31,430 ‫sensor reaches the temperature of my hand. 43 00:03:31,500 --> 00:03:35,160 ‫So I get to sit here and hold it and keep warming it up but I'm going to let it go. 44 00:03:35,400 --> 00:03:41,400 ‫And you'll see here in a moment that the temperature will start or continue to drop so are 66 and it's 45 00:03:41,400 --> 00:03:42,530 ‫going to continue to drop. 46 00:03:42,570 --> 00:03:48,300 ‫And what you will notice sometimes there may be an erroneous reading if you will. 47 00:03:48,360 --> 00:03:52,550 ‫So it'll be at 64 It may jump down to 54 and then come right back up. 48 00:03:52,620 --> 00:03:57,800 ‫That is because we don't have I don't have any filtering or any sort of averaging. 49 00:03:57,810 --> 00:04:03,310 ‫I take one sample we take one sample and then we go ahead and make a calculation off of it in order 50 00:04:03,310 --> 00:04:04,470 ‫to make this more robust. 51 00:04:04,470 --> 00:04:09,540 ‫If you're doing like a critical design you would most likely want to do something where you take three 52 00:04:09,540 --> 00:04:13,580 ‫or four samples and get the average of them and use that value as opposed to taking one. 53 00:04:13,650 --> 00:04:19,830 ‫But this is just to show you that you can use external analog temperature sensors to actually display 54 00:04:19,830 --> 00:04:25,890 ‫a digital temperature and that is the temperature interface demonstration running on the already built 55 00:04:25,980 --> 00:04:26,370 ‫inboard.