MSP430FR4xx UART works in Debug mode but not in release mode

Rohan,

The issue could be in your initialization code for the UART peripheral that could be allowing it to work when being stepped through in debug mode but not when allowed to run on its own. Please provide the following information to help solve this problem:

- Initialization code
- Images of where the error occurs, etc.

Regards,
Michael Arriete

Most probably this is happening because you are sending the data before the MSP430 clock stabilizes. When you are in debugging mode, the clock is already stabilized before you run the program. So UART works correctly. But in release mode, when you do a hardware reset, it sends the data before the clock is stable. So you do not get correct data. If this is the case, it should work if you add a delay of 10 milli-seconds or more before sending the data for the first time. Try this, I hope it should work.

Regards,

Vaibhav

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Hello Michael,

I am using two simple initialization routines. One for the two pins (RXD and TXD) to configure them as the peripheral and not GPIOs.

Second for configuring the UART registers. Following is the code for initialization.

CODE:

int main(void) {

//Stop the watchdog timer
WDTCTL = WDTPW | WDTHOLD;

// Disable the GPIO power-on default high-impedance mode to activate
// previously configured port settings
PM5CTL0 &= ~LOCKLPM5;

//Configure the I/O pins on the ports.

port_config();

//Setup the UART registers

uart_set();

char *s = "My first UART string\n";

sendStringOnUART(s);

return 0;
}

Functions definitions are as follows:

void sendStringOnUART(char *stringToSend)
{
int i=0;
int string_length = 0;

string_length = strlen(stringToSend);
for(i=0;i<string_length;i++)
{
       UCA0TXBUF = stringToSend[i];
       while((UCA0STATW & 0x0001) == 1){
        }
}
}

void uart_set(){

UCA0CTLW0 = 0x0001;

UCA0CTLW0 = 0x00B1;

UCA0CTLW1 = 0x0000;
UCA0BRW = 0x0008;
UCA0MCTLW = 0xD600;
UCA0CTLW0 = 0x00B0;

}

void port_config(){

P1SEL0 = 0x01;
}

There is no specific error that occurs. Only that the string can be seen on the terminal while using the debug mode, but garbage values are displayed when run in release mode, i.e. without connecting the board to the PC or running with Code composer studio.

Appreciate your help on this.

Thanks,

Rohan L

If you are not connecting the board to the PC, to what and how do you connect the communication? How and what voltage do you supply to the board?

Leo,
Following are the two cases where I am getting the difference.

1. I Build the code using Code Composer studio, no errors, and then I go to the debug mode. At this time the board is connected to the PC using a USB cable, and the TXD and RXD pins (and GND of course) on the board are connected to the PC using a UART to USB converter (On a different USB port). I run the code in debug mode and I see the string on the PC terminal (I am using Tera-Term for this) perfectly, without any garbage values.

2. I download the code on the microcontroller and disconnect the board from the PC(USB cable), however I keep the TXD and RXD pins connected to the PC through a UART to USB converter. I connect the board to a power supply through the USB cable. Now both the power on reset and hardware reset using the switch give me garbage values on the Terminal.

Note: In both the cases the baud rate calculated valued are same in the code, and the same baud rate is on the PC.
Also, I checked the output from the board pins in both cases using a logic analyzer. In first case the Logic analyzer detected the string, but in second case it gave erroneous output. Therefore, there is no fault in Terminal emulator or UART to USB converter.

Please let me know your inputs on this. I have posted my entire code above.

Thanks,
Rohan L

Rohan,

Did you try adding a delay before sending the string for the first time as I suggested in my reply above?

After your step 1. you can stop debug CCS, disconnect the LP from your PC and connect and external power supply. You don’t need to re-flash the program as you describe in your step 2. This will run exactly the same program as during CCS debug.

Verify if the ground levels are all the same and not carrying any noise. If possible supply your LP from a battery.

Hi Vaibhav,

Yes, I did try doing that. But that did not work. I got the same garbage values on the Terminal.

Thanks,
Rohan L

Vaibhav,
Thank you for your suggestion. I will try giving a delay after UART initialization and see the results.

-Rohan

Vaibhav,
Thanks for your solution. It is working fine after adding the delay of 200 msec. It is now working will in release mode as well without giving out any garbage values.

Thanks all to other suggestions as well.

Thanks,
Rohan

You are welcome Rohan! It's good to know that your problem is solved.

Regards,
Vaibhav

Leo,
Thank you for the inputs.
That gives a different perspective for board bring up, and will solve my problem in a more technical manner.

-Rohan