TSS721A: The TSS721A was not communicating with my Micro controller

Hello Sakthi,

I am not sure about which evaluation board you're talking. The document you have pointed to contains the full schematic of the described design, while as one can see, in the portion you have pasted in, the resistors at the optocouplers are labeled as nc. If this is really the case with the HW you have in hands, then of course the optocoupler interface will not work.

I am attaching an old application report for the TSS721A device, which certainly can help you understanding the details of this part and its application. I hope this helps.

Best regards

PeterTSS721 Application Report_20140408.pdf

In that Schematic That Resistor R8,R10 i placed  the 10KOhm Resistance but it was not Communicated with the Controller.

Hi Sakthi,

for the U5 optocoupler R8, R10 and R11 need to be populated. I am not sure about the values. You need to check with the datasheet of the optocoupler for the correct values. I any case I would recommend to measure the signals with an oscilloscope to make sure they look as they should for proper communication.

If you send me some scope shots, I can probably tell you more.

Best regards

Peter

Sakthi,

could you tell us the values of R16,R17 and C45. They are necessary for the functionality.

till Now I did not place any components in NC places please help me to select the Correct value for the components in those places.

I want to Develop a Mbus(Meter Bus) Devices For that I need this TSS721A ic I am already Having Mbus Master Device with me with that master I try to Communicate the Micro Controller Through this transceiver Ic, on that it does not Communicate.

So I develope the base testing board as like the above-mentioned schematic, I didn't place any components in that NC places.

Kindly help me to Calculate the components value in that NC places.

I use

R16-->100R

C45-->0.1uf

R17-->30K

U5,U6--> ps2561al-1-a

R8,R14-->100R

R10,R11-->0R I

try with these values but its does not communication. I try With & without of R18 also. But the transceiver not communicating with my controller.

I tried with that value also its was not communicating,
know tried without opto-coupler also but its was not communicating.
i tried that code with normal usb to tll logic also that time basic usart code working perfectly.
but while i use these transceiver ic it was not communicating with terminal window.
Please help me.

Now it was communicating with Controller but gives junk value i attached here

Here i use opto coupler

R10,R11,R8,R14 with 1Kohm

C40 10uf

Please help me to Solve these Error.

Hi Sakthi,

could you please check the UART Frequency. Please use an Oscilloscope to check the signal line, if there are spikes , to lose the communication.

Here i attached the serial terminal window,

Mbus Master to TTL

In below i send some value through Mbus master to other end using TSS721A. it Receive in other end perfectly through RXI line from Opto Coupler

TTL to Mbus Msater.

In below i send some value through TTL to other end using TSS721A. IT Transmit in other end  through TXI line from Opto Coupler, But it getting Echo in the Transmission side itself. IS this is any issue or its the nature of this IC?

If this is an issue please help me to solve.

Hi Sakthi,

sehen sie das Signal nach dem Optokoppler mit einem Oscilloskope? Empfängt der Master irgend etwas?

Hi Sakthi,

sorry I have asked in the wrong language.

Do you see any signal at the RXI Pin after the Optocoupler? Could you measure the signal with an oscilloscope?

Is the Master seeing any signal at his TX line?

I don't have Digital Oscilloscope With So i cant able to Share the Screen Shots & i am unable to check the frequency also. 

In Data Sheet of TSS721A  (http://www.ti.com/lit/ds/symlink/tss721a.pdf)  at pageno.4 they give that this ic will give Echo like that i think so.

Is there any way to solve that through hardware (or) We need to Handle that thinks in Frimeware only.

Hi Sakthi,

although we understand, that you're trying to solve the problem with minimum investment, still electrical engineering is always related to HW, sometimes including Firmware and Software too.

Not having appropriate tools and thus lacking respective information from your side, I am afraid the support from our side, helping you to debug the problems is very limited. It is essential to make sure your HW operates properly, before it makes sense trying to solve the problem by FW. Even at the stage where HW would be functional, debugging FW without being able to check the signals on your HW makes debugging extremely difficult or potentially in some cases even impossible.

As soon as you're able to provide the requested information, we will be happy to support you, until then I am afraid we will suspend the support at this point.

Best regards

Peter