WEBVTT 00:00.150 --> 00:06.930 As you already know, when you start or restart an out in a program, all the data stored in the valuables 00:07.110 --> 00:08.470 is completely gone. 00:08.850 --> 00:13.560 Every time you start from scratch, it could be useful to store a value. 00:13.560 --> 00:17.570 For example, the setting which replaces the default one. 00:18.060 --> 00:22.950 Let's say you are printing the temperature from the sensor and you offer two options. 00:23.220 --> 00:30.540 Either you can display the temperature in degrees Celsius or in degrees Fahrenheit and you can change 00:30.540 --> 00:32.940 between them by pressing on the push button. 00:33.390 --> 00:40.020 Well, if you can't save the sitting every time we start or restart the program, you will get the same 00:40.020 --> 00:40.950 default setting. 00:41.310 --> 00:47.880 However, if you are able to save it for later, when you restart the program, you can just read what 00:47.880 --> 00:51.020 was the previous setting and apply it directly. 00:51.390 --> 00:54.150 The April memory, solve that issue. 00:54.630 --> 00:59.840 During the execution of the program, you can save different values to the memory. 01:00.330 --> 01:07.620 Those values are stored just like values would be stored on your hard drive for your computer when you 01:07.620 --> 01:09.010 restart your computer. 01:09.330 --> 01:13.050 The run is gone, but not the data on your hard drive. 01:13.770 --> 01:19.980 So when you restart the program, you can read the data previously stored in the EPROM and use it to 01:19.980 --> 01:21.190 do whatever you want. 01:21.720 --> 01:24.520 So the principle is quite easy to understand. 01:25.060 --> 01:31.240 Now, before we actually use EPROM for the first time, there are some limitations you have to know 01:31.260 --> 01:32.500 to correctly use it. 01:33.090 --> 01:37.050 First, not all Arduino boards have a memory. 01:37.470 --> 01:44.040 It's available on Nonno and Maiya, for example, but not on Arduino zero. 01:44.970 --> 01:51.330 Then the storage is super limited on untrainable such as window and nano. 01:51.630 --> 01:59.220 You can only store one thousand twenty four values, each one being about between zero and two hundred 01:59.520 --> 02:00.260 fifty five. 02:00.690 --> 02:04.140 So that's a very small memory on average. 02:04.150 --> 02:07.890 Amiga, it's full time, bigger, but still very small. 02:08.670 --> 02:15.780 And one important thing to always remember on a given address of the EPROM, you only have about one 02:15.780 --> 02:18.060 hundred thousand writing cycles. 02:18.630 --> 02:26.940 You can read Evalu as many times as you want, but when you write to Epuron after 100000 writing operations 02:26.940 --> 02:34.180 on a given address, this address will be kind of weird off and it won't work anymore. 02:34.980 --> 02:38.850 So from all those points, we can make some conclusions. 02:39.510 --> 02:44.480 EPROM with only be useful to store very small values and not too often. 02:44.970 --> 02:51.780 The best example is a default setting you want to override with the previous sitting from the last execution 02:51.780 --> 02:53.000 of your Arduino program. 02:53.640 --> 03:00.990 Don't expect to store things like photos or videos or even text larger than, let's say, two pages. 03:01.440 --> 03:08.850 And then due to the limitation of the writing cycles, never, ever write in your EPROM at full speed 03:09.060 --> 03:15.960 in the void look function of your program or in any other infinite loop that goes very fast, you would 03:15.960 --> 03:21.170 quickly reach the one hundred thousand limit and then the address can't be used anymore. 03:21.750 --> 03:28.680 So test your program before if you are not sure and if you correctly test your program before writing 03:29.010 --> 03:31.980 it from memory, well, you will not have any problem.