SCI UART shows incorrect data after porting to FLASH programming 28377S

Other Parts Discussed in Thread: TMS320F28377S

Hi,

after having changed my launchpad to run on flash instead of ram, I found a new problem in the UART communication using SCI. I want to send over a test string character by character. This string being "abcdefghijk". However, when I set my receiving end to the same baud rate, I get a sequence of wrong characters. When just sending 1 character at a time, for example 'a' I still get wrong bytes at my receiving end.

When sending 1 string of "abcdefhijk" the receiving end gets "▒xx▒x▒x▒x<▒x▒x▒x▒x<▒▒x▒x▒".  This was received by using putty. (I also tried screen to record using a raspberry pi)

I have checked on the clock frequency and the divider of the baudrate. I want to get 1MBaud, with a clk of 200MHz this means that I should have a divider of 24. I also have tried a baudrate of 115200. Next to that I also tried if there was any difference on running the code from flash or ram, this didn't seem to make a difference at all.

I also tried to see what happens on a linux device which is recording. So I tried to find the baudrate of the signal accoring to a linux command "stty". This reported that there should be a baudrate of 9600. When I tried to record on this baud rate no date was to be found.

my setup:

- Launchpad XL TMS320F28377S

- connection via debug cable

- 200MHz clock

- 24 clock divider

part from main to init the sci

void initSCIA(void) {

	//configure GPIO
	//Pins - see launchpad schematic
	//84 - transmitter port - output
	//85 - receiver - input
	//Principle - see reference manual
	//Registers - see reference manual
	//Options - see specification manual
	 EALLOW;
	 //connection function
	 GpioCtrlRegs.GPCMUX2.bit.GPIO84 = 1;
	 GpioCtrlRegs.GPCMUX2.bit.GPIO85 = 1;
	 GpioCtrlRegs.GPCGMUX2.bit.GPIO84 = 1;
	 GpioCtrlRegs.GPCGMUX2.bit.GPIO85 = 1;
	 //async interface
	 GpioCtrlRegs.GPCQSEL2.bit.GPIO84 = 3;
	 EDIS;

	 //configure SCIA
	 //1 stop bit, no loopback, no parity, 8 bit char, idle-line protocol
	 SciaRegs.SCICCR.all = 0x0007;

	 //unit in software reset, disable RX ERR, SLEEP, TXWAKE, enable TX, RX
	 SciaRegs.SCICTL1.all = 0x0003;

	 SciaRegs.SCICTL2.bit.TXINTENA = 1;
	 SciaRegs.SCICTL2.bit.RXBKINTENA = 1;

	 //216 - 115200 baud - 1M152 bit/second, LSPCLK = 200MHz
	 //24 - 1000000 baud - 10M bit/second, LSPCLK = 200MHz
	 //divider = LSPCLK/(SCIBaudRate) - 1
	 SciaRegs.SCIHBAUD.all = 0x0000;
	 SciaRegs.SCILBAUD.all = 24; //216
	 //SciaRegs.SCILBAUD.all = 216;

   	 SciaRegs.SCICTL1.all = 0x0023;  // Relinquish SCI from Reset

}

Part from scio_io.c

int SCI_write(const char * buf, unsigned count)
{
    uint16_t writeCount = 0;
    uint16_t * bufPtr = (uint16_t *) buf;

    if(count == 0) {
        return (0);
    }

    while(writeCount < count){
        while(!SciaRegs.SCICTL2.bit.TXRDY);
        SciaRegs.SCITXBUF.all = *bufPtr;
        writeCount++;
        bufPtr++;
    }

    return (writeCount);

}

Part from main, used to call sci functions

	char returnString[20];
	char testReadValue = 0x61;
	int i;

	for(i = 0; i<10; i++){
		returnString[i] = i+testReadValue;
	}

while(1){ SCI_write(&returnString[0], 10); //reply with received byte DELAY_US(50000); }