Using Timer4 capture input on BeagleBone

Still waiting for a response!

I took some time to play with both settings of the PORGPOCFG bit. The pin still acts as an output. I verified that when in GPIO mode 7, the pin can be set to an input and receives my PPS signal correctly.

I would really like to be able to use this feature of the CPU, but without any support from TI, I'll have to change my plans.

David

For the PORGPOCFG bit, 0=enable driver, 1= disable driver.

The pinmux should be setup with the mux mode to select the TIMER4 mode (mode 2 on beaglebone) and the input enabled. I also enabled the pullup on my example.

 I attached a quick StarterWare based demo to show this working. All you need to do is ground the timer4 input and the capture register contents will be shown on the serial port..

  Paul

Paul,

Thank you for the helpful answer. I was able to run your code and verify that the TIMER4 pin is an input.

However, I still don't have success using this pin as an input when I configure timer4's clock source to use TCLKIN.

What I see is that using the following code, the TIMER4 pin is driven low by the processor.

The particular line of code that causes this to happen is the setting of CM_DPLL_CLKSEL_TIMER4_CLK) to CM_DPLL_CLKSEL_TIMER4_CLK_CLKSEL_SEL1.

When I set it instead to CM_DPLL_CLKSEL_TIMER4_CLK_CLKSEL_CLK_M_OSC (the default), then the TIMER4 pin behaves as an input.

I do not understand why the reconfiguration of the timer's clock source causes the I/O pin to change its configuration.

I am driving a 10 MHz clock into the TCLKIN pin for the purpose of having an accurate timestamp clock, as my application requires accurate timing to steer a telescope.

Is a 10 MHz clock fast enough for the resyncing circuits to work properly?

/* Do this to initialize the timers. */
void myDMTimerInit(void)
{
    /* set the xdma_event_intr1 TCLKIN pin to mode 2 */
    HWREG(SOC_CONTROL_REGS + CONTROL_CONF_XDMA_EVENT_INTR(1)) =
        (CONTROL_CONF_RXACTIVE |
        (CONTROL_CONF_MUXMODE(2))    /* mode 2 is TCLKIN*/
        );

    /* set both timer 2 and timer 4 to use TClkIn */
    selectTimerClk(CM_DPLL_CLKSEL_TIMER2_CLK, CM_DPLL_CLKSEL_TIMER2_CLK_CLKSEL_SEL1);

    /* ***** The timer4 select below causes the TIMER4 pin to be always output !!! */
    HWREG(SOC_CM_DPLL_REGS + CM_DPLL_CLKSEL_TIMER4_CLK) &= ~(CM_DPLL_CLKSEL_TIMER4_CLK_CLKSEL);
    HWREG(SOC_CM_DPLL_REGS + CM_DPLL_CLKSEL_TIMER4_CLK) |= CM_DPLL_CLKSEL_TIMER4_CLK_CLKSEL_SEL1;

    /* Load the counter with the initial count value */
    DMTimerCounterSet(SOC_DMTIMER_4_REGS, TIMER4_INITIAL_COUNT);

    /* Load the load register with the reload count value */
    DMTimerReloadSet(SOC_DMTIMER_4_REGS, TIMER4_RLD_COUNT);


    /* Reset the TCLR */
    HWREG(SOC_DMTIMER_4_REGS + DMTIMER_TCLR) = 0x0;
    HWREG(SOC_DMTIMER_4_REGS + DMTIMER_TCLR) = (DMTIMER_TCLR_CAPT_MODE_SINGLE << DMTIMER_TCLR_CAPT_MODE_SHIFT)
                                             + (DMTIMER_TCLR_AR_AUTO << DMTIMER_TCLR_AR_SHIFT)
                                             + (DMTIMER_TCLR_TCM_HIGHLOW << DMTIMER_TCLR_TCM_SHIFT);
    // Currently no support in StarterWare for Capture mode so need to "hardcode"

    DMTimerModeConfigure(SOC_DMTIMER_4_REGS, DMTIMER_AUTORLD_NOCMP_ENABLE);

    /* set the TIMER4 pin to use 1PPS input */
    /* Disable the output */
    DMTimerGPOConfigure(SOC_DMTIMER_4_REGS, DMTIMER_GPO_CFG_1); // 0 = output enabled, 1 = output disabled

    /* Setup up pinmux for Timer 4 as input capture. Input enabled, pull-up enabled, muxmode 2*/
    HWREG(SOC_CONTROL_REGS + CONTROL_CONF_GPMC_ADVN_ALE) =
              (2 << CONTROL_CONF_GPMC_ADVN_ALE_CONF_GPMC_ADVN_ALE_MMODE_SHIFT)    |
              (0 << CONTROL_CONF_GPMC_ADVN_ALE_CONF_GPMC_ADVN_ALE_PUDEN_SHIFT)    |
              (1 << CONTROL_CONF_GPMC_ADVN_ALE_CONF_GPMC_ADVN_ALE_PUTYPESEL_SHIFT)|
              (1 << CONTROL_CONF_GPMC_ADVN_ALE_CONF_GPMC_ADVN_ALE_RXACTIVE_SHIFT) |
              (0 << CONTROL_CONF_GPMC_ADVN_ALE_CONF_GPMC_ADVN_ALE_SLEWCTRL_SHIFT);
}

David

Did thsi help resolve the issue?

Paul

Paul,

Hi. I was away from this problem for a few weeks as other tasks came up.

I have taken the code you provided and inserted it into my application. The TIMER4 input now behaves as an input.

I have no idea what I was doing wrong, but that's the nature of this beast, I suppose.

Thanks for the help!

Hello Sir,

Is it possible to show me how to configure HW_EVT_CAPT with an input event (timer pin) for triggering

the ADC? And how to configure the Pinmux  mode for timer function, because the kernel does not have these

mux functions on beaglebone pad (P8.7 , P8.8, P8.9, P8.10) after checking.

Thanks in advance for the help!

Geoff