Rs232 level converter

Maybe some other users used this board with no problem, but I do seriously warn you that this board may get you into serious trouble.

It's just an ordinary lab oscilloscope with its internal screenshot function. More specifically, one made by Tektronix. It's fairly easy to remember that for basic serial comms, the numbers to know are 2, 3 and 5. Two and three are data, five is ground.

The problem is always to keep track of which data line is which Fantastic tip!!! It all falls into place. I'm cured! Thanks a bunch!! This makes your microcontroller a DCE modem , as opposed to a DTE terminal , and as such, you should connect this to a computer which is a DTE using a straight-through DE-9 cable, not a null-modem cable.

I believe this is accurate - if it's not, feel free to correct me. Interfacing with many industrial devices via RS requires using flow control. I second that request! A unit that supports ALL the handshaking lines would be fantastic!

Having a module to take care of this automagically would be great. Perhaps a Maxim MAX would also be suitable? It has the advantage of not requiring external capacitors which should allow smaller, more flexible installations Didn't work with the IOIO board initially.

It could receive from the PC but would not transmit. I finally did manage to get it to transmit by putting a 70K ohm resistor in series with pin 4. On the IOIO, tx connects to the rx of the shifter board. I just got mine up and running only it's RX pin for now and it works great with hyper terminal. I soldered on downward facing header pins and it slots right into my breadboard. My plan is to use this in a home automation system which generally interfaces via a serial RS DB9 connection.

I bought around 10 of them. Now I have one broken, I would like to replace U2 but I do not know the part number. Hello I have a maybe stupid question I would like to build a cable with one jack on one side, and this shifter on the other side Ok, so what's the maximum supported voltage? It says that "[it] can run at any voltage", but unless it's made of some sort of otherworldly compounds there should be SOME limit I want to use the board to connect with TTL,the TTL can sends datas to this board,but can't recives datas from the board,is anybody know why?

If you are only getting signals going one way, double check all of your connections between the board and cables. Also, you'll want to check the board with a multimeter. You may have a cold joint somewhere which is degrading signal flow. In Hyper Terminal or any other terminal emulator , you just need to connect to the COM port this appears under on your computer. Check out this tutorial for more detailed information. Beguining with labwiev software, thoughtlessly, i short the transmit and receive lines together with a metal wire to do a test wiout results.

It is possible that the unit is damaged? I have purchased this part. I have gnd and tx connected to the circuit board and the rs connected to the pc. When powered, I am not getting any information through to the pc. Am I missing something? I have been successfully using this converter for a while on 3. Have anyone tried this on a low-voltage board?

I just one to discard this before looking for errors anywhere else. You're not going to run a converter like this on 1. The green LED doesn't light because they have a forward voltage of 2. The 2. I just recieved this item and in testing a loopback I cannot get anything to show in the terminal. The tx led stays lit constantly and if I wiggle or connect and disconnect the the loopback wire the rx led will flicker as I assume it should and I get randem characters in the terminal.

Any help? I've ensured the baud rate etc What am I missing? It sounds like you may either have a loose cable connection or damaged board or something. Send us an email at techsupport sparkfun.

These are generally pretty reliable little boards, so if the loopback test isn't working for you, there could be a problem. Is there a good easy way to change the female db9 header to male.

I am looking for a small profile adapter. You'd have to swap pins 2 and 3 which would involve a bit of trace-cutting. Operating notes. The nF capacitor is used to generate the V supply for transmitting data back to the host.

It is charged from the host computers transmit signal coming into the adapter via the 1N diode. For many applications this is a quick and simple way to interface to an RS port, however it isn't a universal solution, therefore if it works for you all's well and good, if not time for a MAX or a similar. The circuit is so simple you can construct it on some strip board, or even wire it up ' birds nest' fashion.

However, for a professional job I've done a PCB layout for it because it's quite a useful adapter to have around. On the 4-pin connector the signals are:. RS transmit data out 3. To help you the connector has pin numbering on it. It is always better to check each module separately. So we will test our converter to see if its working fine. For testing we will use a Hyperterminal a Windows software that can be quickly used to open COM ports and send and receive textual data.

Note your PC might be having more than one COM port but commonly only one is available outside the rest are connected internally to modems etc. Make sure that Hyperterminal has the input focus and type something on the keyboard, they should echo on screen. Now disconnect the RX from TX and do the same. This time you should not see any thing on screen. Now your circuit is ready and working correctly. If the characters are not echoing to screen your circuit is not working as expected.

Check your connections and try changing the COM port in Hyperterminal. Facing problem with your embedded, electronics or robotics project? We are here to help! Post a help request. Avinash Gupta is solely focused on free and high quality tutorial to make learning embedded system fun! More Posts - Website.

Follow Me:. Thank u very much for ur wonderful tutorial, I enjoyed myself, may GOD continue to encourage u. My question is this what is MCU I need further explaination on this. It is a single chip computer. An example is AVR series from Atmel.

They are easy to use and this tutorial series is dedicated to them. More info on MCUs is here. Hi, Avinash You have a beautiful and rare values: spread knowledge and patience. Thanks a lot. Hyperterminal by default does not echos the locally typed characters.

So characters are transmitted but not shown on screen. The screen only shows the received characters. First tell me that have you connected the MCU at other end or just using the level converter and performing a loop back test? If this is so then hyperterminal is sending command to the port you are expecting it otherwise may be a internal serial port may be connected to modem is getting the data.

I will have to control all of them with the PC. This is just for test. Finally u have to write ur own code in PC as well. Thats fine no need to get Visual Studio. Do you have any knowledge of using Windows API? You can search the net for tutorial on serial communication in C. If you can mail me a brief requirement of you app then I can give you some suggestion or if the application is small i will develop it for u! I have also used JAVA before too.

My Email address is jkzh gmail. And about the program I need, I think it is quite simple. I will 1 Master and 2 Slave. One slave is going to have a temperature sensor and the other one will control the intensity of a light bolt via PWM. So the PC program will just have to tell the user the current temperature and be able to increase-decrease the intensity of the light.

Please Avinash, give me as much advise as you can. This is the first time I try interfacing something trough serial with a PC. I will go into more in depth once I complete the basics.

I again thank you for your feedback, they are most valuable for improvement of contents. I also request other users to give feedback, just anything they thing. I would be very glad to hear.

Hey Avinash, i can not thank you enough for taking the pain all this information compiled in the simplest manner possible.

It has been of great help to me, and your site is one of the few that is so simple, conscience and yet complete in all respect.

Thanks a lot for your appreciation. I am happy that many peoples are getting help from my website. Avinash, Very intresting. I need a help I want to rotate stepper motor at particular rotations cw and ccw I want to control through computer help what are all I need I am very fresher.

I also wanted pressure sensor if over load it come to original position. But when Tx and Rx are not shorted,hyperterminal shows some random characters which appear only when i move the wires connected to Tx and Rx. Yes the Power Pins are missing as the schematic software automatically connect them properly and hide them. Its your colorful, easily understandable, detailed, accurate, error free tutorials that makes you to proud on me.

I found many tutorials on net but the way you express the things is different from others. It shows your class Warm Regards!

I am facing a strange issue implementing serial communication of the 16fa pic with a pc. I am using the above tutorial and have the following issue: when i use the assembly language everything works fine. I send a string from the pic and received it to the pc. When i use the c language i send the string from the pic and i received stranger characters. Hi Avinash, Thanx for your fabulous tutorials.

I wanted to know if we can use a usb-serial converter to connect the serial port with a laptop. If so then how will the baud rate and other settings modified. I want to interface a AT command compatible phone through RS with my laptop. It is also necessary to define the voltage states for the control signals as these are widely used within RS The data is sent serially on RS, each bit is sent one after the next because there is only one data line in each direction. This mode of data transmission also requires that the receiver knows when the actual data bits are arriving so that it can synchronise itself to the incoming data.

To achieve this a logic 0 is sent as a start bit for the synchronisation. This is followed by the data itself and there are normally seven or eight bits. The receiver obviously has to know how many data bits to expect, and there are often small dual in line switches either on the back of the equipment or inside it to set this information.

After the data itself a parity bit is sent. Again this requires setting because it is optional and it can be even or odd parity. This is used to check the correctness of the received data and it can indicate whether the data has an odd or even number of logic ones. Unlike many systems these days there is no facility for error correction.