TMS570LS1224: Problem with receive interrupt in SCI/LIN when used for SCI

Sourabh Khemka

Part Number: TMS570LS1224
Other Parts Discussed in Thread: TM4C123GH6PM, HALCOGEN

I am setting-up UART between TMS570LS1224 and two TM4C123GH6PM (Cortex-M).

One TM4C123 communicates via the SCI peripheral (SCI1) and am trying to communicate with the other TM4C using SCI2 (SCI/LIN) peripheral of the Hercules Launchpad (LAUNCHXL-2 TMS57012). SCI1 is functioning pretty well but things'r not going well with SCI2.

I have used HALCoGen to generate code for SCI pepripherals to work at 115200 baud rate, 1 stop bit & parity disabled and both SCI1 & SCI2 are configured for the RX INT interrupt.

But data transmitted by TM4C to the SCI2 doesn't cause any receive interrupt and hence am not able to receive using SCI2.

While trying to debug for any problems with the SCI2 peripheral, it was quite surprising to find that when I transmitted data bytes from SCI1 on the same Hercules launchpad to the SCI2 pins, everything functioned very well. I even tried communicating with SCI2 using Putty on my PC (Board was connected to PC using launchpad's USB port which connects with both XDS-110 & SCI2) and was able to communicate by this method too.

So the problem arises only when I use TM4C123GH6PM to send data to SCI2 (everything goes well in case of SCI1). I am using the UARX and UATX pins on J6 to connect SCI2 with TM4C.

Please help me out with this. Do I need to use some extra circuit or module to communicate with SCI2 peripheral ? or the problem lies somewhere else, because the same SCI2 periph. is functioning well when connected to some other transmitter (eg: SCI1 of same launchpad)

This is my first question on this community platform so please tell me if I'm not able to ask the question clearly

over 5 years ago

0 QJ Wang over 5 years ago

TI__Guru**** 197126 points

Hello,

Sourabh Khemka said:
it was quite surprising to find that when I transmitted data bytes from SCI1 on the same Hercules launchpad to the SCI2 pins, everything functioned very well.

Do you use the SCI2 signals (LIN_TXD, and LIN_RXD) on J6 for this test? How do connect SCI1 and SCI2?

How do you connect TM4C SCI signals to TMS570 SCI1/SCI2 signals?

0 Sourabh Khemka over 5 years ago in reply to QJ Wang

Prodigy 60 points

Hello,

Yes, I used SCI2 on J6 for the test and have also tried it using SCI2's LIN_TXD n LIN_RXD on J10.

I have soldered male headers on J6 and have connected it to SCI1 or the TMC using jumper wires

0 QJ Wang over 5 years ago in reply to Sourabh Khemka

TI__Guru**** 197126 points

Hello,

SCI2 is also connected to TM4C129 MCU on board to TX and RX to/from mini USB. When the external TM4C123 device transmit characters to SCI2, is the SCI2 in service with PC through the miniUSB?

From your test,

SCI1 TX --> SCI2 RX ----- works, there is SCI2 RX interrupt

The SCI2 pins on the header should work without any issue.

0 Sourabh Khemka over 5 years ago in reply to QJ Wang

Prodigy 60 points

I tested it for both scenarios,
(a) when external TM4C transmits to SCI2 the miniUSB is connected to PC , and (b) when external TM4C transmites to SCI2 the miniUSB is not connected (in this case board was powered on by supplying 5V using a battery and voltage regulator)

The problem persists even when microUSB is not connected to PC.

Also I tried transmitting to SCI2 by Arduino Mega (ATMega 2560) and it works in this case too, but the point is arduino works on 5V logic but our's is on a 3V logic.

Thanks

0 QJ Wang over 5 years ago in reply to Sourabh Khemka

TI__Guru**** 197126 points

From you tests (SCI1->SCI2, ATMega2560 -> SCI2), it seems to me that the SCI2 works without any issue, and the problem is related to TM4C UART.

0 Sourabh Khemka over 5 years ago in reply to QJ Wang

Prodigy 60 points

The point is, TM4C -> SCI1 works properly and the there is problem only the case TM4C -> SCI2.

Scince, it works with SCI1, I don't feel there's issue with TM4C123.

Are there any special requirements of SCI2 which the TM4C is not able to satisfy ? (SCI2 is also connected to on-board TM4C129, are things going wrong due to this?)

Thanks

0 QJ Wang over 5 years ago in reply to Sourabh Khemka

TI__Guru**** 197126 points

There is not special requirement for SCI2 than for SCI1. To check if the onboard TM4C129 affects your test, you can pull the IRSTN of TM4C129 (pin 10 of header J12) down to GND, then run your test.

0 Sourabh Khemka over 5 years ago in reply to QJ Wang

Prodigy 60 points

Thanks a Lot :)

This has solved the issue.

Is any resistor also required to be used for grounding the IRSTN of TM4C129 ?

Thank You

0 QJ Wang over 5 years ago in reply to Sourabh Khemka

TI__Guru**** 197126 points

It is not required.

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TMS570LS1224: Problem with receive interrupt in SCI/LIN when used for SCI