TIDA-00527: TIDA-00527

divyanshu bawa

Part Number: TIDA-00527
Other Parts Discussed in Thread: SN65HVD1780

We are using power over RS485 in TIDA00057. We have the the board for the same having SN65HVD1780 IC With diffeerent value of inductor in pcb

We are sending data us from arduino at 115200 baud rate. And receiving at the arduino at same baud rate.

We are facing problem in sometimes the data get lost sometimes it get corrupted,sometime it show well. when we close the serial terminal. Can u help me knowing what can be the reson for the same.

over 5 years ago

0 Hao L over 5 years ago

TI__Mastermind 25705 points

Divyanshu,

What's the communication distance? Is there any ground potential difference between two Arduino? Do you see the communication quality is better by 'closing the serial terminal'? Can you show on the schematic where the terminal is? Can you check the bus waveforms to tell when the problem shows up? One common question about this design is that you need to make sure the signal is DC balanced (1 and 0 bits are roughly equal in the data). Some encoding, like Manchester or 8b/10b is necessary.

Regards,

Hao

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

Its Hardly 1-2 meter. No both the ground are common.

The communication starts when we close the slave terminal.

SN65HVD 1780 .....RE is open , DE is shorted with 5v (Always transmitting)...D as TX from one arduino..A and B to next IC SN65HVD 1780. Taking R from receiver to another arduino. DE as open and RE as ground.

Yes the Signal is DC balanced using Manchester encoding

0 divyanshu bawa over 5 years ago in reply to divyanshu bawa

Expert 1325 points

I am using Manchester.h library from Arduino and try to send data serially and passing though TIDA00527 and receiving from other end using arduino serial.

The problem I am facing is the data I am getting data at recieiver end continuously but the bits I am sending is different in code and what actually I see in serial monitor for transmitter

And getting different in serial monitor for receiver

Please help me on this

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

Waiting for ur reply

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

There..?

0 Hao L over 5 years ago in reply to divyanshu bawa

TI__Mastermind 25705 points

Divyanshu,

Can you be more specific what you meant 'close the slave terminal'? Does it mean the slave terminal (receiver end) is connected to the bus?

Can you do the experiment starting with a clock pattern data? Let's make sure the hardware work as it's supposed to be.

Regards,

Hao

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

Lest Start from the starting i am using arduino to transmit some bits to slave. Below is the code I am trying to solve it using software

#define TX_PIN 1

void setup()
{

man.setupTransmit(TX_PIN, MAN_9600);

}
void loop()
{

man.transmit('0');

}

This is transmitting code from my arduino using Manchester.h library. But i am not able to get how the 0 is sending in form of garbage i am receiving at the terminal how can i decode it..? I am getting this at the termianl

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0 Hao L over 5 years ago in reply to divyanshu bawa

TI__Mastermind 25705 points

Hi,

Can you probe the bus to check if the waveforms make sense? If you cannot, is it possible to try the communication with the regular RS-485 setup first?

Regards,

Hao

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

But for The way the message is encoding in manchester.h library i am not able to get that. at the termianl

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

Do u have Manchester encoding simple code so that i can make it work on arduino or any other uc

0 Hao L over 5 years ago in reply to divyanshu bawa

TI__Mastermind 25705 points

Hi,

I'm sorry I mostly deal with hardware issues. I've never used Manchester codes in Arduino. Can you post this specific question separately? Some engineers in other groups in TI might be able to help you.

Regards,

Hao

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

What would be best way either to go with software thing or by hardware...?

0 Shawn Standfast22 over 5 years ago in reply to divyanshu bawa

Intellectual 400 points

Simple questions - Have you verified that the baud rates are configured the same for both the transmitter and the receiver? What about the baud rate between the receiver and your terminal monitor? Where is the Manchester data decoded? Can your serial monitor terminal decode Manchester or do you need your receiver to decode it first?

Have you checked the power supply rails are stable at your receiver? Check them with an O-Scope since a DMM won't be able to capture fast dips in the rail. Provide plots if you're able to. Remember when using a distributed power system like the PoE - the supplies now have a high output impedance at AC frequencies. This means that proper use of decoupling capacitors and distributed bulk capacitance is important at the receiver side to eliminate HF power supply ripple on the receiver side.

Can you also provide scope plots of the serial data leaving the transmitter and entering the receiver, (X,Y and A,B terminals). Signal integrity issues could be the culprit and scope plots will help diagnose that.

Shawn

0 divyanshu bawa over 5 years ago in reply to Hao L

Expert 1325 points

I am able to get the data without TIDA00527 Using manchester encoding. But i need Your help in debugging the Circuit output. Attached is the waveoutput at Signal TX,A,B For Sn65hvd17806242.Powerover_RS485.zip