CC2640R2F: Switching between LDO and DC-DC modes at runtime

Hi Vsevolod,

Have you looked at the DriverLib API for power control? There is APIs available to shift source from software:

dev.ti.com/.../group__pwrctrl__api.html

Hi Max,

Thank you for the answer! Yes I seen this.

Do we have any examples how and when to use it?

Is there any restrictions? Can I use the function in an interrupt context?

Hi,

You should be free to use it from both Task and ISR context as far as I know. However, I fail to see how this would improve the customer situation? The GLDO and DC/DC is internally connected to each other, switching to the GLDO would not eliminate the connection to the inductor. This means that the risk of interference via the inductor remains, even in GLDO mode.

I would suggest they test out, using for example a LaunchPad, how they see it being impacted by the presence of the expected field in both use-cases. If they find it to be a problem, I would assume they would have to actually run in GLDO mode only, excluding the inductur from the design. 

Max,

The customer and I sugggest that in GLDO mode the DCDC_SW pin have HiZ mode and there will be no current flow through the inductor.

Hi V,

That could be, but I would not rule out some other dependency. This is why I suggest you actually try it out with for example an LaunchPad to verify the behavior before applying it to the actual product.  

Hi Max,

We tried to implement the switching to LDO using the code:

#include <power_switcher.h>
#include <driverlib/pwr_ctrl.h>
#include <ti/drivers/PIN.h>
#include <ti/drivers/pin/PINCC26XX.h>
#include "board.h"

volatile int pin_value = 0;
static PIN_State PowerSwitchPinState;
static PIN_Handle PowerSwitchPinHandle;
const PIN_Config PowerSwitchTable[] = {
    CC2640R2_LAUNCHXL_HALL_SENSOR | PIN_INPUT_EN | PIN_NOPULL | PIN_IRQ_BOTHEDGES | PIN_HYSTERESIS,
    PIN_TERMINATE
};

static void PowerSwitchPinIntHandler(PIN_Handle handle, PIN_Id pinId) {
   if(handle == PowerSwitchPinHandle) {
       power_switcher_check();
   }
}


void power_switcher_init() {
    PowerSwitchPinHandle = PIN_open( &PowerSwitchPinState,PowerSwitchTable);
    if(PowerSwitchPinHandle == NULL) {
        return;
    }

    PIN_registerIntCb(PowerSwitchPinHandle,&PowerSwitchPinIntHandler);
    PIN_setInterrupt(PowerSwitchPinHandle, CC2640R2_LAUNCHXL_HALL_SENSOR | PIN_IRQ_BOTHEDGES);

}

#pragma FUNCTION_OPTIONS(power_switcher_check, "--opt_level=0")
void power_switcher_check() {
    pin_value = PIN_getInputValue(CC2640R2_LAUNCHXL_HALL_SENSOR);
    if(PIN_getInputValue(CC2640R2_LAUNCHXL_HALL_SENSOR)) {
            PowerCtrlSourceSet(PWRCTRL_PWRSRC_DCDC);
    } else {
            PowerCtrlSourceSet(PWRCTRL_PWRSRC_GLDO);
    }
}

We see that GPIO Irq callback is processed when a magnet is close to board. But invoking PowerCtrlSourceSet have absolutely no effect.

Also we tried to call PowerCtrlSourceSet(PWRCTRL_PWRSRC_GLDO); in SimplePeripheral_init and this also have no effect.

We still observe oscillations on DCDC_SW pin after invoking PowerCtrlSourceSet(PWRCTRL_PWRSRC_GLDO) func.

Max, please advise how to disable the DCDC for a some time?

Max,

Thank you!

We add PowerCC26XX_tirtos.c to the project and add flag checking in prior to SysCtrl_DCDC_VoltageConditionalControl(); we achieved the switching to LDO.