1 00:00:00,940 --> 00:00:09,130 So in this lesson we're going to write our first S.P. or SS I driver and in this lesson we're just going 2 00:00:09,130 --> 00:00:17,500 to write a very simple interface that can make our microcontroller serve us an SBA master to communicate 3 00:00:17,560 --> 00:00:19,810 with an SBA slave. 4 00:00:19,810 --> 00:00:25,330 So over here we're just going to show the various steps required in order to be able to do that. 5 00:00:25,540 --> 00:00:33,820 So we're going to design a system basically that allows our microcontroller to send alphabet to an SBA 6 00:00:33,820 --> 00:00:34,540 slave. 7 00:00:34,600 --> 00:00:42,770 So in our project we have an imaginary SBA sleeve which we are going to interface with. 8 00:00:42,970 --> 00:00:49,150 And after this example we're going to take a look at a much more practical example. 9 00:00:49,300 --> 00:00:54,700 We're going to take a look at much more practical example and this will be right in the driver to interface 10 00:00:54,700 --> 00:01:03,160 with a graphic liquid crystal display an LCD screen for plotting graphs etc. and we're going to write 11 00:01:03,190 --> 00:01:05,660 the SSA driver for that after this one. 12 00:01:05,710 --> 00:01:11,890 But let's take this very simple example first so that you can see how simple it looks before we start 13 00:01:11,890 --> 00:01:14,030 dealing with the LCD. 14 00:01:14,170 --> 00:01:26,410 Because what happens is different SBA an eye to see slaves have their own memory maps so often at times 15 00:01:26,470 --> 00:01:32,700 when you are interface and to a particular SBI or a to see slave. 16 00:01:32,710 --> 00:01:40,960 You spend most of your time communicating using these specific address address locations required by 17 00:01:40,960 --> 00:01:42,170 that device. 18 00:01:42,190 --> 00:01:49,570 And this this or these address locations differ among slave devices. 19 00:01:49,570 --> 00:01:55,350 That is why in this first example we're not going to write the code for any particular slave. 20 00:01:55,360 --> 00:01:57,180 We have an imaginary slave. 21 00:01:57,290 --> 00:02:05,370 We are just going to demonstrate how to initialize the GPA to initialize the SSA module select the marginal 22 00:02:05,450 --> 00:02:14,140 slave and send the alphabet A to Z to that slave and then we're going to take the LCD as a slave in 23 00:02:14,140 --> 00:02:15,440 the next lesson. 24 00:02:15,460 --> 00:02:17,800 So I've created a project here. 25 00:02:17,830 --> 00:02:25,710 I'm calling this simple SSI and I'm going to come over here to target this tea and 4C. 26 00:02:25,760 --> 00:02:29,260 One two three right and I'll drop down over here. 27 00:02:29,260 --> 00:02:31,300 Source group I'm going to name it up 28 00:02:42,930 --> 00:02:48,580 and I'm going to create a new far right click add new item to c file I call this main 29 00:02:52,820 --> 00:02:58,400 and I'm going to set my debugger here. 30 00:02:58,620 --> 00:03:02,510 This is the distilleries ICD. 31 00:03:02,550 --> 00:03:06,900 I come to cities and then resets around over here. 32 00:03:06,990 --> 00:03:07,400 Okay. 33 00:03:07,410 --> 00:03:07,690 And then. 34 00:03:07,730 --> 00:03:08,510 Okay. 35 00:03:08,590 --> 00:03:14,380 And then I right click here and then include follow on to this file here like this. 36 00:03:14,610 --> 00:03:15,390 Right. 37 00:03:15,420 --> 00:03:25,420 So we start off by opening our main function into main and then open close and then open our infinite 38 00:03:25,420 --> 00:03:30,880 loop while one open and close. 39 00:03:30,880 --> 00:03:31,320 Right. 40 00:03:31,720 --> 00:03:35,220 So we're going to write two functions for our SS I. 41 00:03:35,230 --> 00:03:37,060 Or SBA module. 42 00:03:37,060 --> 00:03:42,170 And we're going to write these functions down here and then we'll call them from the main function. 43 00:03:42,190 --> 00:03:49,870 So before we we write the function is let's recap on the various steps we need to take in order to properly 44 00:03:49,870 --> 00:04:00,100 configure the SS I or SBA module so I'll be using the name SS here because TVC often refers to the SBI 45 00:04:00,520 --> 00:04:07,260 as SSI too I'll be saying SSI just keep in mind is still SBA. 46 00:04:07,360 --> 00:04:14,410 So in order to use in a peripheral device as we know because of the clock gate and mechanism we've got 47 00:04:14,410 --> 00:04:18,440 to enable clock access to the power for a device. 48 00:04:18,450 --> 00:04:19,840 So we'd have to do that. 49 00:04:19,930 --> 00:04:27,310 But apart from that we would have to set up our GPL you first and then go on to set up our SBA module. 50 00:04:27,310 --> 00:04:34,090 So we need to enable the clock to GPL open using the RC GC GPA or register. 51 00:04:34,090 --> 00:04:41,380 Then after that we go to the alternate function select register and set the pin as sporting a function 52 00:04:41,620 --> 00:04:47,790 once that is done we go on and set the digital enable pin. 53 00:04:48,070 --> 00:04:58,240 We digitally enable our SBA piece and then we go to the controller register and assign SBI as the alternate 54 00:04:58,240 --> 00:05:00,340 function that we wish to use. 55 00:05:00,700 --> 00:05:05,950 Once that is done then we can go on to start initialize the SBA module itself. 56 00:05:05,950 --> 00:05:17,580 And with that we will start off by enabling clock access to the SS a module using the RC GC SS I register. 57 00:05:17,580 --> 00:05:25,860 And once that is done we've got to set the bits rate using the SSA C P S R which is that pre-schooler 58 00:05:25,870 --> 00:05:33,910 register and also we've gotta set the mode to phase that polarity and we do it as using the SS I see 59 00:05:34,000 --> 00:05:40,240 our 1 C I receive a register which is the SS I control register 0. 60 00:05:40,240 --> 00:05:47,770 Once that is done we're going to set a y SSI module which is all microcontroller to master and we set 61 00:05:47,770 --> 00:05:53,770 it to a master or slave but in this case we want to set it to a master and we do this using the SS AI 62 00:05:53,800 --> 00:05:57,970 control register 1 which is SS I see are 1. 63 00:05:58,360 --> 00:06:06,700 Once this is done we can go ahead and enable the SS AI module through the SS AI control register 1 again 64 00:06:07,140 --> 00:06:16,570 then we will be done with the is setup now to select our sleeve we set the slaves select signal. 65 00:06:16,570 --> 00:06:23,410 So if we have multiple slaves would have to select them by sort of set and the slave select right. 66 00:06:23,500 --> 00:06:28,210 So this just a brief overview I don't expect you to remember since we're going to write a code here 67 00:06:28,710 --> 00:06:38,420 which come down here start a function I call this SSA in it. 68 00:06:38,680 --> 00:06:39,190 I 69 00:06:42,130 --> 00:06:49,330 know it this is a void function open close like a nation. 70 00:06:49,320 --> 00:06:55,460 We start off by allowing clock access to the SSI module and the GPL. 71 00:06:55,460 --> 00:06:59,260 You report that our SSI will be connected to. 72 00:06:59,500 --> 00:07:09,460 So I'm gonna come over here and say RC GC system control is in the system control system control RC 73 00:07:09,490 --> 00:07:14,830 GC SS AI and then we're going to use SSA 1. 74 00:07:14,920 --> 00:07:27,700 So I'm going to pass to over here and 2 is 0 x 2 and in binary you know is 0 1 and this corresponds 75 00:07:27,700 --> 00:07:28,690 to SSA 1 76 00:07:32,210 --> 00:07:37,310 so this will enable clock access to SS I want once that is done we come over here 77 00:07:44,920 --> 00:07:48,640 actually to reduce the typing noise I'm just gonna bring this here. 78 00:07:48,910 --> 00:07:56,570 Come over here and then we're neighbor clock access to keep your port D for the SSA. 79 00:07:56,810 --> 00:08:01,540 Once that is done we're going to enable clock access. 80 00:08:01,540 --> 00:08:07,750 Let's say our slaves select being is going to be connected to GPL you port F so we're going to enable 81 00:08:07,750 --> 00:08:10,810 clock access to GPL you f as well 82 00:08:18,910 --> 00:08:29,310 once that's done we're going to configure port deep in three and one for the SS I clock and SS I transfer 83 00:08:29,310 --> 00:08:40,430 lines respectively so we start off by doing it at proper we would disable the analog mode by accessing 84 00:08:40,440 --> 00:08:50,710 the M select for these pins and then we're going to digitally enable these same parents once that is 85 00:08:50,720 --> 00:08:54,350 done we're going to enable the alternate function 86 00:08:58,160 --> 00:09:03,700 and once that is done we're going to assign the alternate function to be SS i1 87 00:09:06,480 --> 00:09:09,490 and we'll do it by clearing it first. 88 00:09:09,570 --> 00:09:17,020 So we first color and then we set in the PTL register. 89 00:09:17,310 --> 00:09:18,930 Then we set like this. 90 00:09:20,610 --> 00:09:25,700 OK so once this is done we've got to configure P F to us. 91 00:09:25,700 --> 00:09:27,390 This leaves select a pin. 92 00:09:27,400 --> 00:09:32,880 And this is basically set in the pin as an hour to put the pin so you can post the video and try to 93 00:09:32,880 --> 00:09:37,530 do that yourself since you should be familiar with that. 94 00:09:37,650 --> 00:09:44,310 And like I said or if I've not said it you know how to look locate registers from the data sheet. 95 00:09:44,370 --> 00:09:51,630 So if there is a particular register or a particular assignment that you do not understand you can always 96 00:09:51,630 --> 00:09:53,040 go to the data sheet. 97 00:09:53,100 --> 00:10:00,960 For instance let's say let's say one week later you sort of open this example and you see this line 98 00:10:00,960 --> 00:10:05,130 here and you want to know why this line. 99 00:10:05,130 --> 00:10:07,590 Why do we pass to here. 100 00:10:07,650 --> 00:10:15,660 Or you have to do is expand this to here this hexadecimal to I should put it like this so they you know 101 00:10:15,660 --> 00:10:17,510 it's hexadecimal too. 102 00:10:17,950 --> 00:10:25,260 So expand this into binary form and then you would see the bit that is enabled if you find a bit of 103 00:10:25,260 --> 00:10:31,200 data and there would you simply need to go to the data sheet locate this register and read the meaning 104 00:10:31,200 --> 00:10:31,950 of that bit. 105 00:10:32,310 --> 00:10:42,900 And in this case you realize that by setting bits one in the RCC SS a 1 register we enable SS I module 106 00:10:42,900 --> 00:10:45,150 1 right. 107 00:10:45,190 --> 00:10:50,550 And you can do it for all of the other registers. 108 00:10:53,040 --> 00:10:53,540 OK. 109 00:10:53,540 --> 00:11:02,450 So we did tally enable our sleep select pin and I'm going to set it as outputs by access in the direction 110 00:11:02,450 --> 00:11:09,710 register and I'm going to initialize it by keeping it high over here like this. 111 00:11:09,710 --> 00:11:21,220 Once that is done we can go and do the the SBI parameters configuration such as set in it to either 112 00:11:21,260 --> 00:11:27,410 slave or master sets in the out the pole the polarity to phase 113 00:11:30,040 --> 00:11:31,560 and other things. 114 00:11:31,600 --> 00:11:34,630 So we start we start off by disabling the SBA module 115 00:11:38,940 --> 00:11:47,510 and then we want to say we're using the system clock and we do this by set in passing 0 to the ICC register. 116 00:11:47,510 --> 00:11:52,100 And once that is done we're going to add a pre-schooler off to. 117 00:11:52,230 --> 00:11:54,840 So we access the pre-schooler register to do this 118 00:12:00,470 --> 00:12:09,980 and once this is done we're going to set the clock to eight mega herds SBA mode and 8 bits of data. 119 00:12:10,990 --> 00:12:12,760 And we do this by access and the 120 00:12:15,550 --> 00:12:19,900 control register 0 and that's what we have. 121 00:12:20,430 --> 00:12:24,390 And once we've done this we can enable the SSI module 122 00:12:31,320 --> 00:12:31,760 right. 123 00:12:32,390 --> 00:12:36,170 So this over here initialize is the SSI. 124 00:12:36,170 --> 00:12:40,080 This the initialization sequence for the SSA. 125 00:12:40,370 --> 00:12:41,530 So. 126 00:12:41,690 --> 00:12:47,690 So let's say we want to write to the SSI we're going to create a function here they'll show us how to 127 00:12:47,690 --> 00:12:49,490 write to the SSA module. 128 00:12:50,000 --> 00:12:53,280 So it's also going to be a void going to save for it. 129 00:12:53,420 --> 00:12:54,770 This would be SS I 130 00:12:57,700 --> 00:12:59,850 right. 131 00:13:00,280 --> 00:13:02,210 And it's going to take us argument. 132 00:13:02,230 --> 00:13:04,000 What we want to write 133 00:13:07,070 --> 00:13:10,350 open close so too right. 134 00:13:10,360 --> 00:13:19,290 We need to set the slave assets law first and then we wait until the fight for it's not empty and then 135 00:13:19,290 --> 00:13:23,110 we transmit the debate. 136 00:13:23,210 --> 00:13:32,850 OK so first and slave I said is GPL you f and then we said data register would disable our slave I said 137 00:13:32,850 --> 00:13:39,970 to be we disable our slaves elect been by passing through X it's your fault over here. 138 00:13:40,500 --> 00:13:46,590 Once they done we'll wait until the fight for is not full and we do this by accessing the SSI status 139 00:13:46,590 --> 00:13:47,700 register. 140 00:13:47,790 --> 00:13:49,140 I'm just going to say while 141 00:13:53,550 --> 00:14:02,540 SSI 1 status register and 2 while this is equal to zero 142 00:14:12,890 --> 00:14:15,470 we just wait here. 143 00:14:15,470 --> 00:14:23,850 And once we've made sure the FIFO is not food we can transfer our data into the SSI data register. 144 00:14:23,870 --> 00:14:34,330 So say SS I won the R because the argument passed to the function which is data and once that is done 145 00:14:37,110 --> 00:14:39,910 we can keep the slaves select line. 146 00:14:39,920 --> 00:14:40,200 Hi 147 00:14:43,340 --> 00:14:46,940 but before we do that we've got to wait for the transmit to be complete. 148 00:14:46,940 --> 00:14:52,490 We have to make sure that transmission is completed so we can use another while loop here. 149 00:14:52,510 --> 00:14:53,360 So I'll say a while 150 00:15:00,430 --> 00:15:13,030 SS i1 studies register and this time zero x once you so you can go to the data datasheet and see what 151 00:15:13,030 --> 00:15:15,760 this means by checking the SS. 152 00:15:15,760 --> 00:15:22,470 I stayed to register and expand in this to it to its binary form. 153 00:15:22,480 --> 00:15:26,290 If you do that you would see which bit it corresponds to. 154 00:15:26,710 --> 00:15:29,620 Okay so once this is done we simply say 155 00:15:32,270 --> 00:15:33,760 keep the F 156 00:15:36,370 --> 00:15:46,410 data register pass 0 x 0 4 over here and stay here. 157 00:15:46,480 --> 00:15:46,910 Right. 158 00:15:47,290 --> 00:15:52,860 So this is how simple it is to write to the SSA module. 159 00:15:52,930 --> 00:15:56,580 But the problem is when we start interfacing with other slaves. 160 00:15:56,620 --> 00:15:59,180 The slaves would have various requirement. 161 00:15:59,530 --> 00:16:06,010 You would have to send a number of commands you have to be able to differentiate between right in data 162 00:16:06,040 --> 00:16:11,680 to the slave versus right in command configuration command to the slave. 163 00:16:11,680 --> 00:16:16,920 Something like something like an accelerometer or a gyroscope. 164 00:16:16,960 --> 00:16:19,330 You may need to configure its first. 165 00:16:19,330 --> 00:16:25,780 Maybe you have to configure it to read that data in 8 bits 12 bits or 16 bits and in order to do this 166 00:16:26,140 --> 00:16:35,670 you've got to write commands to the gyroscope so right in the command would have to go through a different 167 00:16:35,670 --> 00:16:43,610 sequence which will be different from reading actual data and perhaps the gyroscope is not actually 168 00:16:43,610 --> 00:16:48,270 a good example because here you're right in command and ingredient data. 169 00:16:48,310 --> 00:16:56,180 Let's say the LCD which we shall see we would have to write command to the LCD screen as well as write 170 00:16:56,210 --> 00:16:57,830 data to it. 171 00:16:57,920 --> 00:17:07,620 So we would have to write command such as we would have to write a command to clear the screen write 172 00:17:07,650 --> 00:17:17,630 a command to configure the LCD such as say the LCD configuration we've got to write the LCD physical 173 00:17:17,630 --> 00:17:24,080 parameters as a command to the LCD for the initialization sequence and the where we have to do this 174 00:17:24,410 --> 00:17:27,940 will be somewhat different from right in raw data. 175 00:17:28,340 --> 00:17:34,900 For instance there is something known as the IRS and the US line we've got to set the R S line low. 176 00:17:34,940 --> 00:17:42,800 We're right in command instead of C S lay high but this is just a simple example with regards to LCD 177 00:17:43,130 --> 00:17:47,140 or graphic LCD especially the one we're going to deal with with other sleeves. 178 00:17:47,240 --> 00:17:48,840 It's a bit more nuanced. 179 00:17:48,930 --> 00:17:57,110 They've got a particular sequence for sort of interacting with them but this very clean example shows 180 00:17:57,560 --> 00:18:03,350 how to initialize the SSA module and how to write to it right. 181 00:18:03,380 --> 00:18:05,180 So I'm going to bring the prototype here 182 00:18:23,680 --> 00:18:29,140 so when we are ready to test this file we have to do is initialize 183 00:18:38,000 --> 00:18:47,570 and then let's say we said we are going to make it look like it's right in alphabet so I'm going to 184 00:18:47,570 --> 00:18:51,250 say on sine character 185 00:18:55,810 --> 00:19:01,080 all right over here and in here I'm going to use 186 00:19:04,010 --> 00:19:07,090 going to have a loop here c for 187 00:19:09,790 --> 00:19:22,020 i a coarse character a and I is less than character C less than or equal to should we include see to 188 00:19:22,020 --> 00:19:23,600 it. 189 00:19:23,760 --> 00:19:24,540 Plus plus 190 00:19:30,060 --> 00:19:37,750 C as I can call SSI right. 191 00:19:38,020 --> 00:19:38,490 All right 192 00:19:42,130 --> 00:19:42,500 right. 193 00:19:42,530 --> 00:19:51,680 So this is all that will be required if we have an SS a device or S.P. I slaved device that receives 194 00:19:53,240 --> 00:19:55,440 that we've connected to our board accordingly. 195 00:19:55,520 --> 00:20:02,840 This is what will be written and if the slave defied device can easily decode the data it would just 196 00:20:02,840 --> 00:20:09,830 receive ABC and display it but like I said we're not going to try that because we don't have I don't 197 00:20:09,830 --> 00:20:11,080 have that slave device. 198 00:20:11,090 --> 00:20:15,390 This is just to show you the initialization in the right sequence. 199 00:20:15,410 --> 00:20:16,570 So that's all there is to it. 200 00:20:16,730 --> 00:20:26,200 For this lesson we can make sure there are no errors at least by compiling it. 201 00:20:27,130 --> 00:20:27,430 OK. 202 00:20:27,430 --> 00:20:30,440 There are no errors so that's all there is for this lesson. 203 00:20:30,450 --> 00:20:36,010 And I'll see you in the next lesson as we write that drive for the liquid crystal display. 204 00:20:36,010 --> 00:20:36,720 I'll see you later.