Electrical – UART Communication with PuTTY

I am struggling to understand how to work with UART interface between microcontrollers. I don't know if this happens because I can't understand how it works or because I manipulate it in a wrong way. In any case,I try to be hands on ,trying to understand how it works quickly and get the taste of it but so far I am unsuccessful.I have read several tutorials about the "theory" but I am having difficulties being hands-on.

Here is what I am trying to do: I have a MCU (CC1310 on a launchpad) with a UART port. I try to see if I can make this MCU talk to my PC first by sending some data. Later I need to make this MCU talk with another MCU.

First, I have to mention that this launchpad has a XDS 1100 Debugger linked to the computer via USB.There are some jumpers on the board with RX TX so I suppose this allows the XDS110 to act as FTDI converter USB to UART directly via a USB port (I also have a special cable from Prolific to probe signals without going through the debugger).

In Code Composer Studio, I have imported and built a project named uart_echo for the CC1310. I found this example in Ti Resources Explorer. I managed to build the project (as I didn't change anything and this code was written by Texas Instruments) and load it into the chip by using the debugging button.

The code in this file is the following:

    /*
 * Copyright (c) 2015-2016, Texas Instruments Incorporated
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * *  Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * *  Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * *  Neither the name of Texas Instruments Incorporated nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 *  ======== uartecho.c ========
 */

/* XDCtools Header files */
#include <xdc/std.h>
#include <xdc/runtime/System.h>

/* BIOS Header files */
#include <ti/sysbios/BIOS.h>
#include <ti/sysbios/knl/Task.h>

/* TI-RTOS Header files */
#include <ti/drivers/PIN.h>
#include <ti/drivers/UART.h>

/* Example/Board Header files */
#include "Board.h"

#include <stdint.h>

#define TASKSTACKSIZE     768

Task_Struct task0Struct;
Char task0Stack[TASKSTACKSIZE];

/* Global memory storage for a PIN_Config table */
static PIN_State ledPinState;

/*
 * Application LED pin configuration table:
 *   - All LEDs board LEDs are off.
 */
PIN_Config ledPinTable[] = {
    Board_LED1 | PIN_GPIO_OUTPUT_EN | PIN_GPIO_LOW | PIN_PUSHPULL | PIN_DRVSTR_MAX,
    Board_LED2 | PIN_GPIO_OUTPUT_EN | PIN_GPIO_LOW | PIN_PUSHPULL | PIN_DRVSTR_MAX,
    PIN_TERMINATE
};

/*
 *  ======== echoFxn ========
 *  Task for this function is created statically. See the project's .cfg file.
 */
Void echoFxn(UArg arg0, UArg arg1)
{
    char input;
    UART_Handle uart;
    UART_Params uartParams;
    const char echoPrompt[] = "\fEchoing characters:\r\n";

    /* Create a UART with data processing off. */
    UART_Params_init(&uartParams);
    uartParams.writeDataMode = UART_DATA_BINARY;
    uartParams.readDataMode = UART_DATA_BINARY;
    uartParams.readReturnMode = UART_RETURN_FULL;
    uartParams.readEcho = UART_ECHO_OFF;
    uartParams.baudRate = 9600;
    uart = UART_open(Board_UART0, &uartParams);

    if (uart == NULL) {
        System_abort("Error opening the UART");
    }

    UART_write(uart, echoPrompt, sizeof(echoPrompt));

    /* Loop forever echoing */
    while (1) {
        UART_read(uart, &input, 1);
        UART_write(uart, &input, 1);
    }
}

/*
 *  ======== main ========
 */
int main(void)
{
    PIN_Handle ledPinHandle;
    Task_Params taskParams;

    /* Call board init functions */
    Board_initGeneral();
    Board_initUART();

    /* Construct BIOS objects */
    Task_Params_init(&taskParams);
    taskParams.stackSize = TASKSTACKSIZE;
    taskParams.stack = &task0Stack;
    Task_construct(&task0Struct, (Task_FuncPtr)echoFxn, &taskParams, NULL);

    /* Open LED pins */
    ledPinHandle = PIN_open(&ledPinState, ledPinTable);
    if(!ledPinHandle) {
        System_abort("Error initializing board LED pins\n");
    }

    PIN_setOutputValue(ledPinHandle, Board_LED1, 1);

    /* This example has logging and many other debug capabilities enabled */
    System_printf("This example does not attempt to minimize code or data "
                  "footprint\n");
    System_flush();

    System_printf("Starting the UART Echo example\nSystem provider is set to "
                  "SysMin. Halt the target to view any SysMin contents in "
                  "ROV.\n");
    /* SysMin will only print to the console when you call flush or exit */
    System_flush();

    /* Start BIOS */
    BIOS_start();

    return (0);
}

Then I used PuTTY. I looked at my COM port in Windows and found out :

Class Application / USER UART : COM 10
Class Auxiliary Data: COM 9

I opened PuTTY and selected Serial communication, COM 10 / COM 9 and input 9600 in the baud rate.

It opened the PuTTY console but there was nothing inside. I could not even type anything.

What I am doing wrong ?