Data transmission through uart in tms320f28335 experimenters kit

RANJANA ORAM

Other Parts Discussed in Thread: TMS320F28335, CONTROLSUITE, MAX232

Hi, i am using TMS320F28335 Experimenter Kit for data transmission through uart. I have used an example code which is available in the control suite. I am running Sci_Echoback example code in CCS 6.0.1 , I have to transmit the data to arduino uno, I am successfully transmitting the data which is crosschecked using an external software. But I am unable to receive the same data in arduino. Using a mixed domain oscilloscope I have seen the waveform of the tx pin in delfino and it gives pulses whose max is 5.3 volts and min is -5.3 volts. I believe that any controller board cannot give negative voltage. It's digital low should be 0 volts. I think my board is not functioning properly or it is damaged. Can anyone please tell how to check whether the board is working properly? And is the tx pin of delfino board suppose to give a pulses like it was explained earlier ?

over 9 years ago

0 Gautam Iyer over 9 years ago

Guru 192875 points

Hi Ranjana,

Can you tell us, which pins on the experimenter kit are you measuring?

Regards,
Gautam

0 RANJANA ORAM over 9 years ago in reply to Gautam Iyer

Prodigy 50 points

I am measuring the "tx" pin on the delfino board with respect to ground using a mdo(mixed domain oscilloscop). Is there any other way?? Please let me know..

0 Gautam Iyer over 9 years ago in reply to RANJANA ORAM

Guru 192875 points

You mean these pins:

0 RANJANA ORAM over 9 years ago in reply to Gautam Iyer

Prodigy 50 points

Yes the very same ones..

0 Gautam Iyer over 9 years ago in reply to RANJANA ORAM

Guru 192875 points

Have you connected these pins directly to UNO? If yes, try connecting the SCIA GPIO pins instead of the above pins.

0 Brett Larimore over 9 years ago in reply to Gautam Iyer

TI__Guru 57255 points

Hi Ranjana,

First off, I would recommend that you take a look at the schematics for the F28335 cCARD and the Docking Station/Experimenter's Kit baseboard (DIMM100 variety). You can find both of these within controlSUITE.

J3's TX and RX pins are routed into the controlCARD. There they connect to a RS232 transceiver and then to GPIO28/GPIO29 (assuming SW1 is connected). The transceiver will translate the SCI signals into RS232 ones, which is why you are seeing +/- 5V on J3's pins.

I am not too familiar with the Arduino UNO system, but I'd recommend trying to see what kind of voltage levels it expects to connect to.
- If RS232, I'd connect it to J4.
- If it expects 0-3.3V, I'd connect directly to GPIO28 and GPIO29 on the Docking Station. You'd then need to set SW1 (on the cCARD) into the OFF position to remove contention.

(in a systems sense: using RS232 is preferred if the distance between systems is large enough - it adds robustness)

Thank you,
Brett

0 Gautam Iyer over 9 years ago in reply to Brett Larimore

Guru 192875 points

Yes Brett, you're absolutely right. TX & RX pins on docking station are RS-232 level. She'll require an external RS-232 to TTL converter like MAX232 to communicate with UNO
OR
She can directly interface SCIA pins to UNO but she needs to take care of the RX signal as it would be 5V and a voltage divider is required in its path to scale down to 3.3V

Regards,
Gautam

0 RANJANA ORAM over 9 years ago in reply to Gautam Iyer

Prodigy 50 points

Hi, i have connected the GPIO29 pin to the arduino uno. In arduino voltage from 3.3v to 5v is considered as digital high, so i didn't require a TTL converter. Now i am successfully able to retrieve the data in arduino. Thanks a lot Brett and Gautam...

Regards,
Ranjana

0 Gautam Iyer over 9 years ago in reply to RANJANA ORAM

Guru 192875 points

Fantastic Ranjana!

Goodluck & Regards,
Gautam

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Data transmission through uart in tms320f28335 experimenters kit