PROTOCOLS: UART - I2C - SPI - Serial communications #001

Cyril communication is always handy when you need to send digital data using few connections there are a lot of serial communication protocols but a few are more popular than the other especially when using basic microcontrollers such as the peak or the Arduino today we will see what is a civil communication protocol and we will see three main examples what communication I Square C and spi I will tell you the main characteristics of each one of these show you how they work and why you use one and not the other and also show you a small example using the Arduino we should also see the signals on the oscilloscope in order to get a better view and by that understand more so let's see how the word I square C and SPI work but before make sure you subscribe and activate a notification bell and also thanks to all my patrons for the support so let's get started the sponsor of this video is JAL CPCB thanks to all users feedback they are improving their services every day even this is your first time ordering pcbs is very easy and all you have to do is to upload the Gerber files to genesee PCB dot-com select the settings that you want and you could get five PCBs of any color for only $2 what's up my friends welcome back so what is a serial communication protocol well it's a way of transmitting data in a line one data after the other and in this case we are talking about digital data imagine that you want to send the number 198 which in binary which are just ones and zeros will be 1 1 0 0 0 1 1 0 you could connect a wire for each bit and send the height digital poles for once and the low value for zeros and do that at the same time so in just one moment you can send all the bits at the same time this is called a Perl communication the downside of this kind of communication is that we have to use 8 connections plus the ground reference so a total of 9 cable but this is for 8-bits imagine that you want to send a 16-bit data in that case who will need 17 cables and usually we want fewer connections so instead of sending the data each bit at the same time what we will do is to place the bits in series and then we send each one one after the other using just one cable but you could already see the downside of this type of communication if we send 16 bits in parallel we need only one clock post to send all the data if we send the same data using serial communication we'll need 16 clock pulses to save the same amount of data so this will be 16 times slower so that's the main disadvantage of using serial communication as examples for Silla communication we have the S bus the PPM the JTAG connection word I square C the can SPI MIDI usb RS 233 and more and even the Morse code could be a serial communication okay guys so we have mentioned that clock pulses before depending on this clock co communication could be synchronous or asynchronous and the main difference is that one uses the clock to send the data at a specific speed and time and the asynchronous doesn't have a clock so how do you know where one bit will end and where the next bit will start if you don't have any clock to understand that we start with the most basic a synchronous i/o communication what or universal a synchronous receiver transmitter this type of communication uses only one cable to send the data plus the ground reference the transmitter cable will be named TX and the receiver will be rx the transmitter starts sending bits whenever it wants so how does the receiver know when the incoming data starts where it ends when we have a bit or the other and so on for that what communication will need to play some common configuration between the transmitter and receiver before making the connections you need to make sure that both the X and the Rx will work with the same settings three of these settings are the transmission speed in both per second the data length in bits and how is the start and the stop bit so let's see what are these imagine that you want to send the number before 198 the representation in digital process of this will be this one so with this data we already know that we will send 8 bits so now we know the data length the transmitter and receiver must have the same configuration but if we analyze the word signal we won't see only these 8 bits we will see something like this that's because word needs a start bit and an end bit usually the word signal is always high and the start bit will be represented by a low pause so that makes very easy for the receiver to detect when the data starts each time we detect a low pause we know that we need to start reading the input data and now here comes the third configuration the speed of transmission without knowing the speed the receiver won't be able to know when one bit will end and the other one will start and by that it will ring the wrong value for that we need to set the speed in bouts per second a very common word speed is 9600 dots per second that means that the length of the bit will be 1 divided by 9600 and that equals to 104 microseconds so now all the receiver has to do after detecting the start bit is to count time we count 104 microseconds and then we are at the beginning of the first input bit but we don't usually save the value here because the data is unstable so we will go in the middle of the bit so we count 52 microseconds more and now we save the first bit and then we count 104 microseconds more and save the second bit and so on once the receiver has Oh 8 bits we'll wait for the stop bit which is represented by high posts and then we can send the receive data from the buffer to the rest of the system this exact same setup could be made with different speeds or different amount of bits for the same data usually the start and stop bits are always like this so that's how the word communication works another version of the word communication is the rs-232 that is used by all computers the arduino for example uses the word communication to upload the codes or send the data to the serial monitor this right here is a wired chip and you also see that it has a DTR pin and sometimes you will see a CTS pin these pins are used to notify that the data terminal is ready and that the receiver is clear to receive so in this way we won't have flow problems I connect the Arduino and here have the word signal on the oscilloscope and right now I'm sending the number before 198 as you can see we have exactly the representation before the start beat the data and the stop beat and the rest of the time the signal is high usually devices will have body TX and the rx pins so they could boot send and receive data with the same protocol okay guys next we need to take a look at the first synchronous serial communication and this is the ice-crazy or the inter integrated circuit this protocol was developed by Philips and in this case we need two connections plus the ground reference one wire will send the data and this will have the name of SDA and the second wire is the clock because this is a synchronous communication and it will have the name of SCL once again we need to specify the amount of bits that we will send and also to note the cut frequency for both the transmitter and receiver usually I square C could work with speed up to 400 kilobits per second and it will send data of 15 or 16 bits in this case at the same time that we send the data we also create a clock post with the same frequency as the bit of the data so the receiver will know exactly when one bit will end and the next one will start so this can go faster since we don't need to count the time as in the word communication also using I square C the transmitter will send all kind of data but only certain receiver will be able to save the values we do that with the use of the slave address each receiver will have a different slave address so the transmitter will first send the address which for example could be 68 then it will send the data so only the receiver with the 68 slave address will store the data into its buffer so the word communication is a one-to-one communication but the I square C could be used with multiple receivers for example this ampule 6050 module uses head classic communication I connect my oscilloscope to the data and Clark pins and now we can see the signal on the oscilloscope as you can see we have a square signal as a clock and then we have the same data each time we send a new value we also enable the clock signal and also send the slave address before sending the new data okay guys so that was ice crazy finally let's take a look at another synchronous serial communication SPI or Cir peripheral interface in this case we still have the clock connection but we also need three more wires mossie which is the master output slave input Mesa which is master input slave output and the chip select wire plus the ground reference so using a total of five connections we could send the data once again we have a master transmitter and the slate that could receive the data the most wire will send the data to the slaves but the master device could also receive data from the slaves using the miso wires in this case we don't use a slave address as for the I square C instead of that we have the chip select to start a new transmission the Master will put a chip select pin to low and then we send the clock and the data signals so if you want more slave devices connected you will need a chip select connection for each one the advantages of this type of communication is that it's full duplex in a full duplex mode both devices can transmit the signal at the same time so we could both send and receive we can do that with I square C because that is a simplest communication also at the same time the speed of transmission for the SPI is way higher than the I square C or what communication and at the same time the power consumption is also lower we can set the amount of bits that we want to send in the code but unfortunately this communication can send the data for long ranges as we can do with the rs-232 or the can bus also these communications have no acknowledged pins so the master could send the data even if you don't have a slave connected and the data won't be receive by any device in case of the word communication we could have the DTR or CTR pins to do that now this other f24 radio module uses SPI communication I connect it to the Arduino and I hook up the oscilloscope we can see four signals for clock MOSI miso and chip select as you can see when we want to the data chief selectees low then we have the clock signal and the master or the slave we'll send the data so that was SPI now you should know more or less how art I Square C&S pay communications work leave a comment below if you want to see other protocols such as the JTAG the kent communication USB and so on i've made this video with these three because these are the most common used with everyday microcontrollers as you could see the arduino has all these types of communication on the same board so i hope that you learn something new if so give a like to this video and if you are not subscribed consider subscribing for more videos also remember to activate the notification bell so thanks again and see you later guys [Music]

Channel: Electronoobs

Views: 761,563

Keywords: serial, uart, spi, i2c, Arduino, how, signals, RS232, CAN, JTAG, explain, theory, DIY, protocol, better, comparison

Id: IyGwvGzrqp8

Length: 11min 58sec (718 seconds)

Published: Sun Aug 11 2019