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MSP432E401Y: Development Kit,TI LanchPad.

Part Number: MSP432E401Y
Other Parts Discussed in Thread: TEST

Hi team,

Here's an issue from the customer may need your help:

The customer has checked these 2 files:

https://dev.ti.com/tirex/explore/node?node=AOD4LXqFA8XEr21FehvtQA__J4.hfJy__LATEST

https://dev.ti.com/tirex/explore/node?node=AEFKJ9Hm67JXdj9NzpSYFA__J4.hfJy__LATEST&search=432E

And got the related description from the Technical Reference Manual:

Here the issue is: the up-count mode cannot set by themselves when to refill.

Some related information for reference:

a. The down-count mode can be set from 10000 to 0.

b. The code is shown below. Simply change TIMER_CFG_B_PERIODIC to TIMER_CFG_B_PERIODIC _UP for 97 lines and change data for 105 lines to 10000 for easy observation of the blinking frequency of the LED.

/* --COPYRIGHT--,BSD
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 *    notice, this list of conditions and the following disclaimer.
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 *    notice, this list of conditions and the following disclaimer in the
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 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
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 * 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,
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/******************************************************************************
 * MSP432E4 Example project for Configuring a timer in 16-bit periodic mode
 *
 * Description: In this example, the timer is configured to generate an
 * interrupt every 0.1 sec in 16-bit periodic mode. On the interrupt the state
 * of the LED D2
 *
 *                MSP432E401Y
 *             ------------------
 *         /|\|                  |
 *          | |                  |
 *          --|RST               |
 *            |                  |
 *            |               PN0|-->LED
 *            |                  |
 *            |                  |
 *            |                  |
 * Author: Amit Ashara
*******************************************************************************/
/* DriverLib Includes */
#include <ti/devices/msp432e4/driverlib/driverlib.h>

/* Standard Includes */
#include <stdint.h>
#include <stdbool.h>

void TIMER2B_IRQHandler(void)
{
    uint32_t getTimerInterrupt;

    /* Get timer interrupt status  and clear the same */
    getTimerInterrupt = MAP_TimerIntStatus(TIMER2_BASE, true);
    MAP_TimerIntClear(TIMER2_BASE, getTimerInterrupt);

    /* Toggle the LED */
    MAP_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0,
                     ~(MAP_GPIOPinRead(GPIO_PORTN_BASE, GPIO_PIN_0)));
}

int main(void)
{
    uint32_t systemClock;

    /* Configure the system clock for 120 MHz */
    systemClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |
                                          SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480),
                                          120000000);

    /* Enable the clock to the GPIO Port N and wait for it to be ready */
    MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPION);
    while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_GPION)))
    {
    }

    /* Configure the GPIO PN0 as output and put in low state */
    MAP_GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_0);
    MAP_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_0, ~(GPIO_PIN_0));

    /* Enable the Timer-0 in 16-bit periodic mode with interrupt generated
     * every 0.1 sec */
    MAP_SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER2);
    while(!(SysCtlPeripheralReady(SYSCTL_PERIPH_TIMER2)))
    {
    }

    MAP_TimerConfigure(TIMER2_BASE, TIMER_CFG_SPLIT_PAIR | TIMER_CFG_B_PERIODIC_UP);
    MAP_TimerIntEnable(TIMER2_BASE, TIMER_TIMB_TIMEOUT);

    /* Since the 16-bit timer can count only 65536 value, we use the pre
     * scaler of 256 to divide down the count rate by 256. Thus the actual
     * count load is 120e6/256 = 468750. Now when to count at 0.1 sec the
     * load value in the timer would be 468750 * 0.1 = 46875 = 0xB71B. */
    MAP_TimerPrescaleSet(TIMER2_BASE, TIMER_B, 255);
    MAP_TimerLoadSet(TIMER2_BASE, TIMER_B, 10000);

    /* Enable Timer Interrupt */
    MAP_IntEnable(INT_TIMER2B);

    /* Enable the timer count */
    MAP_TimerEnable(TIMER2_BASE, TIMER_B);

    while(1)
    {
    }
}

c. The modified code above can be seen at runtime. When the 97-line parameter is TIMER_CFG_B_PERIODIC, the light blinks very quickly, while when it's TIMER_CFG_B_PERIODIC _UP, no such . This is not a 0-10000 up or down count, it's known as 0-65535.

d. The error in c. will not occur when 104 lines are removed and no division is performed.

Could you please help check this case? Thanks.

Best Regards,

Cherry

  • Hi

    GPTIM support count up/down. The value is set through the GPTMTnPR register. Refer to the user's guide. 

    GPTMTBMR register can configure when to update time-out value

  • Hi Allen,

    They configured like this, but it did not work.

    Regards,

    Cherry

  • Hi cherry,

    I have done a lot of test about TIMER. In count down mode the time interval is the TIMER_TBILR value * the prescaler. When I change the TIMER_TBILR value or the Prescaler, the period will change corresponding. But in count up mode, only when prescaler=0, the time interval changes proportionally with the TIME_TBILR value. When The TIMER_RBPR is not 0, the interval seems like 65535*prescaler + TIMER_TBILR.

    I don't know clearly why it behaves like this. It needs some time to find out.

    Customer can use down mode as a work around. For the final function implemented, there is no difference between up and down modes.

  • Hello Allen,

    Thanks and expect your updates.

    Best Regards,

    Cherry

  • Hi Cherry,

    There is instruction in Technical Reference Manual 18.3. As count down mode prescaler act as true divider. But in count up mode it is as a extension, not a 

    true prescaler. That is the reason why count up /down have different behaviors.