Serial Communication RS2. Basics max. Embedded. Serial Communication RS2. Basics. In the previous post, we discussed about the basics of serial communication. In this post, we will learn about the RS 2. Introduction. It is possible to chain Arduinos together in such a way as to get communication between the two. Having ArduinoArduino communication can be useful for. Since the program uses basic serial communication it should work with all versions of the Arduino and other microprocessors. If the Arduino serial monitor is working. I recently found an interesting use of the many Arduino boards that I have. You can use your Arduino board as a bridge to connect serial devices to the computer. Serial communication works on 1s and 0s. Also known as binary, the Arduino sends these 1s and 0s bits one by one, or Serially. These bits are sent in the form of. A New Software Serial Library for Arduino. News NewSoftSerial is in the core Starting with Arduino 1. December, 2011, NewSoftSerial has replaced the old. This is the protocol you will be using the most when involving microcontrollers like AVR. As we proceed ahead in this post, we will deal with the concept of level conversion and towards the end, we have something interesting and practical for you the loopback test Contents. RS 2. 32 Basics. RS 2. Recommended Standard 2. Electronic Industries Association EIA for connecting serial devices. In other words, RS 2. RS 2. 32 is the interface that your computer uses to talk to and exchange data with your modem and other serial devices. The serial ports on most computers use a subset of the RS 2. C standard. RS 2. DB9 port commonly known as serial port, however earlier it was used over the DB2. We will have a look at both of them here. RS 2. 32 over DB 9. The pin configuration of DB 9 port is as follows. Yes, it looks exactly like in fact it is the serial port you would find in older computers. RS2. 32 DB9 Connector. A little more complicated is the ability to control a second I2Cdevice. The MPU6050 always acts as a slave to the Arduino with the SDA and SCL pins connected to the. Introduction Arduino and Matlab Let Them Talk Using Serial CommunicationDB9 Connector Pins. The pin description for the RS 2. DTR data terminal ready When terminal is turned on, it sends out signal DTR to indicate that it is ready for communication. DSR data set ready When DCE is turned on and has gone through the self test, it assert DSR to indicate that it is ready to communicate. RTS request to send When the DTE device has byte to transmit, it assert RTS to signal the modem that it has a byte of data to transmit. V307.png' alt='Serial Communication Arduino' title='Serial Communication Arduino' />Addressing a OneWire device. Each 1Wire device contains a unique 64bit ROM address, consisting of an 8bit family code, a 48bit serial number, and an 8bit CRC. Download Teensyduino, Version 1. Teensyduino is a software addon for the Arduino software. CSiG.png' alt='Serial Communication Arduino' title='Serial Communication Arduino' />CTS clear to send When the modem has room for storing the data it is to receive, it sends out signal CTS to DTE to indicate that it can receive the data now. DCD data carrier detect The modem asserts signal DCD to inform the DTE that a valid carrier has been detected and that contact between it and the other modem is established. RI ring indicator An output from the modem and an input to a PC indicates that the telephone is ringing. It goes on and off in synchronous with the ringing sound. Rx. D Received data The Rx. D pin is the Data Receive pin. This is the pin where the receiver receives data. Tx. D Transmitted data The Tx. D pin is the Data Transmit pin. This is the pin through which data is transmitted to the receiver. RS 2. 32 over DB 2. The pin configuration of DB 2. Yes, it looks exactly like the parallel printer port that you would find in older computersIt is however worth noting that the DB 2. RS 2. 32 or parallely. The pinouts are different in each case. The pinout for RS 2. DB 2. 5 is shown below thanks Thomas and Aaron for clarification. RS2. 32 DB2. 5 Connector. DB2. 5 Connector Pins. As we can see, most of the pins are similar to that of a DB9 port. If you notice, we see that in DB2. Tx. D and Rx. D pairs of pins. Now what does this meanIn simple words, it means that serial communication through the DB 2. Thomas. NOTE Another important thing to note is that the simplest way to in which a microcontroller can communicate to a PC is through Rx. D, Tx. D, and Ground Pins. And this is what we will be doing here and hence forth in upcoming posts. The other pins are not of much use to us, for now. Now this was something about RS 2. Our next topic is level conversion. Btw, have you heard of TTLSounds familiar, but what is TTL Lets read on Logic Level Families. By Logic Level one means the range of voltage over which a high bit 1 and a low bit 0 is accepted in a particular IC, gate, etc. Various logic levels have been standardized, out of which the most popular ones are 1. TTLTTL stands for Transistor Transistor Logic. These days TTL is the most widely used logic. TTL is mostly used in ICs and gates, like 7. A major drawback of the TTL logic is that most of the devices working on the TTL Logic consume a lot of current, even individual gates may draw up to 3 4 m. A. In TTL Logic, a HIGH or 1 is 5 volts, whereas a LOW or 0 is 0 volts. But since attaining exact 5 volts and 0 volt is practically not possible every time, various IC manufactures define TTL logic level range differently, but the usual accepted range for a HIGH is within 3. Beatport Tech House 2012'>Beatport Tech House 2012. LOW is 0 0. 8 volts. LVTTLLVTTL stands for Low Voltage Transistor Transistor Logic. LVTTL is increasingly becoming popular these days, because of the nominal HIGH voltages, and hence lesser power consumption. By lowering the power supply from 5v to 3. There are several transistors and gates, which work on LVTTL logic. Atmels Atmega microcontrollers are designed to work on both, LVTTL and TTL, depending upon the VCC supplied to the IC. In LVTTL Logic, a LOW is defined for voltages 0. V 1. 2. V, and High for voltages 2. V 3. 3. V, making 1. V2. 2. V undefined. RS 2. 32. RS2. 32 is also one of the most popular logic. Though now quite old, it is still in use. In RS 2. 32 logic, a HIGH 1 is represented within 3. V 2. 5 V, whereas a LOW 0 is in between 3. V 2. 5 V, making 3. V to 3. V undefined. Weird isnt it But thats how it is defined Apart from these, there are many other logic families like ECL, RTL, CMOS, LVCMOS, etc. At present, we are not much concerned about them. You can refer to this article to know more about them. Level Conversion TTLRS2. So what is logic level conversionTo interconnect any two logic level families, their respective HIGHs and LOWs must be same else they wouldnt work. For example, when we want to interconnect two devices, one of which works over TTL and the other over RS2. HIGH of TTL which is 3. HIGH of RS2. 32 which is 3v 2. LOW of TTL 0v0. RS2. So you see, here lies the problem If we do not convert the logic levels in this case then the LOW signal of TTL would be interpreted as a HIGH in RS2. The Solution. One solution is to use additional pull up resistors, or to use Zener diodes. A better solution is the use of ICs that directly converts logic levels. Luckily logic level conversion is quite simple these days with the use of ICs like MAX2. CP2. 01. 2 We would talk about all these solutions one by one. Zener Diodes. Zener diodes are widely used to regulate voltage between two points. When Zener diode is used in reverse bias in series with a suitable resistor, and a voltage breakdown voltage is applied across the terminals of the Zener resistor pair, then a voltage V Zener Voltage appears across the terminals of the Zener diode, while the rest of the voltage appears across the terminals of the resistor. The simple circuit below shows how to use Zener diodes to convert logic levels from TTL to LVTTL Note that this circuit is only applicable for high to low logic level conversions Bidirectional Logic level converters are easily available in the market. Some of the websites selling them are Adafruit, Freetronics, Sparkfun, Embedded Market etc. IC MAX2. 32. MAX2. ICs were invented by Maxim. These IC packages are used to convert TTLCMOS logics to RS2. All we need are some passive components, and we are done Below is the circuit diagram of the MAX2. IC. Level Conversion using MAX2. MAX2. 32 is used to convert TTL to RS2. But these days, USB is the most used protocol Everything runs on USB be it printer, scanner, displays or anything But how to convert USB to UART One way is USB  TTL  UART. The other way is to use USB UART bridges which directly convert USB UART. They are widely and easily available these days. Here are some of the websites Robokits, e. Arduino to ESP8. 26. By Serial Communication. Following on from the FTDI ESP8. FTDI serial adaptor you can use an Arduino. Here is how to set up the Arduino to talk to the ESP8. I an using a 5. V Arduino Nano which of course is 5. V. The Esp. 82. 66 is a 3. I am using a voltage divider to bring the Arduinos 5. V down to 3. 3v. If you are using a 3. Arduino then you do not need the voltage divider. The wiring is very similar to the FTDI. Arduino pin 3 to voltage divider and then to ESP8. RXArduino pin 2 to ESP8. TXArduino GND to ESP8. GNDPull CHPD HIGH with a 1. K resistor to 3. V to vcc. You only need the voltage divider on the Arduino TX pin. The 5. V Arduino will read 3. HIGH so you can connect the ESP8. TX pin directly to the Arduino RX pin. Start Program Cmd Windows. Make sure the ESP8. If it does not it may keep resetting and may not broadcast a signal. Arduinos cannot supply enough current and you should use a separate power supply. While experimenting I use a bread board power supply. I am using a simple serial in, serial out sketch. Basic serial communication with ESP8. Uses serial monitor for communication with ESP8. Pins Arduino pin 2 RX to ESP8. TX Arduino pin 3 to voltage divider then to ESP8. RX Connect GND from the Arduiono to GND on the ESP8. Pull ESP8. 26. 6 CHPD HIGH When a command is entered in to the serial monitor on the computer the Arduino will relay it to the ESP8. Software. Serial. Software. Serial ESPserial2,3 RX TX. Serial. begin9. 60. Serial. Start the software serial for communication with the ESP8. ESPserial. begin9. Serial. println. Serial. Remember to to set Both NL CR in the serial monitor. Serial. printlnReady. Serial. println. ESP8. ESPserial. Serial. ESPserial. ESP8. 26. Serial. ESPserial. Serial. Once everything is setup, open the serial monitor and cycle the power on the ESP8. You can now interrogate the ESP8. For more on talking to the ESP8. FTDI ESP8. 26. 6.