Power management in Tiva c

Hello Moz,

The device power management depends on the CPU executing SysCtlSleep or SysCtlDeepSleep function. This would keep the device in idle condition. There are two ways that you can achieve it

1. Use the SysCtlSleep and/or SysCtlDeepSleep to keep the entire device in idle state, periodically set a timer to generate an ADC conversion which will cause the ADC to convert and then send an interrupt to the CPU causing a system wakeup.

2. The CPU can use the SysCtlPeripheralDisable to disable the ADC when conversion is not required, then on a periodic interrupt, enable the clock to ADC, trigger the ADC, read the data and shut down the clock.

The latter I believe has an errata as well, though it is simpler in implementation if the rest of the system is not to be idled.

Regards

Amit

Hi Amit,

Thanks for your reply. I'm able to read ADC every ms on 1ms timer interrupt as you can see in my code. Kindly could you please send me some code which shows how I can put the ADC in sleep/deep sleep and enable the ADC when want to get the ADC value after 1ms. Thanks

See my code below

//
// Enable the Timer in Sleep Mode.
//
SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_TIMER0);

//
// Disable the Adc in Sleep Mode.
//
SysCtlPeripheralSleepDisable(SYSCTL_PERIPH_ADC0);

This is the way iam reading the ADC every ms of timer timer interrupt

//
// Trigger the ADC conversion.
//
TimerControlTrigger(TIMER0_BASE,
SysCtlClockGet() / 1000, true);

while(!ADCIntStatus(ADC0_BASE, 0, false))
{
}

ADCIntClear(ADC0_BASE, 0);

TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

ADCSequenceDataGet(ADC0_BASE, 0, &ADC0ValueS0[0]);

Regards,

Moz

Hello Moz,

I would modify the code as follows

//
// Enable the Timer in Sleep Mode.
//
SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_TIMER0);

//
// Enable the ADC in Sleep Mode.
//
SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_ADC0);

AMIT>> I would suggest using Periodic Mode of the timer and enable the ADC Interrupt, with ADC Interrupt Handler to do the following

ADCIntClear(ADC0_BASE, 0);

TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

ADCSequenceDataGet(ADC0_BASE, 0, &ADC0ValueS0[0]);

AMIT>> For Sleep operations

//
// Trigger the ADC conversion.
//
TimerControlTrigger(TIMER0_BASE,
SysCtlClockGet() / 1000, true);

while(1)

{

SysCtlSleep();

}

Regards

Amit

Hi Amit,

I'm still struggling to understand how I can put the ADC in sleep mode. See my code below

uint32_t ADCValue;

//*****************************************************************************
//
// ADC0 Interrupt Handler
//
//*****************************************************************************
void
ADCIntHandler(void)
{
TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

ADCIntClear(ADC0_BASE, 0);
}

void
ConfigADC(void)
{

SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);

SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);

ADCReferenceSet(ADC0_BASE, ADC_REF_INT);

GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_3);

ADCSequenceConfigure(ADC0_BASE, 0,

ADC_TRIGGER_TIMER, 0);

ADCSequenceStepConfigure(ADC0_BASE, 0,
0, ADC_CTL_CH0 | ADC_CTL_IE | ADC_CTL_END);

ADCIntRegister(ADC0_BASE, 0, ADCIntHandler);

ADCSequenceEnable(ADC0_BASE, 0);

ADCIntClear(ADC0_BASE, 0);
}

void
ADCRead(void)
{

TimerControlTrigger(TIMER0_BASE,
SysCtlClockGet() / 1000, true);

//
// Wait for conversion to be completed.
//
while(!ADCIntStatus(ADC0_BASE, 0, false))
{}

ADCIntClear(ADC0_BASE, 0);

TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

ADCSequenceDataGet(ADC0_BASE, 0, &ADCValue);

Hello Moz,

Since I do not see the place where ADCRead is called and how the timer is being configured, I will suggest the following.

1. Replace

//
// Wait for conversion to be completed.
//
while(!ADCIntStatus(ADC0_BASE, 0, false))
{}

ADCIntClear(ADC0_BASE, 0);

TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

with

SysCtlSleep();

2. Add the following as followes (and same for timer)

SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);

SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_ADC0);

In general, when making changes for Sleep/Deep Sleep, we would require the scope of the entire project, so that it makes it simpler understanding program flow, rather than code snippets (which would mean our suggestions may not be fully functional)

Regards

Amit

Hi Amit,

I'm taking ADC samples every 1ms over 1ms interrupt. I want to put ADC in sleep mode such that when it reads the ADC sample after 1ms, it should go into sleep and should wake up after 1ms to read ADC sample and go back to sleep again. I'm pasting my code below. Kindly could you please modify my code to fulfill the above requirement. Thanks 

Moz

void
TimerIntHandler(void)
{
TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);
}

void
ConfigTimer(void)
{

SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER0);

SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_TIMER0);

TimerConfigure(TIMER0_BASE, TIMER_CFG_PERIODIC);

TimerLoadSet(TIMER0_BASE, TIMER_A, SysCtlClockGet() / 1000);

IntMasterEnable();

TimerIntEnable(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

IntEnable(INT_TIMER0A);

TimerEnable(TIMER0_BASE, TIMER_A);

}

void
ADCIntHandler(void)
{
TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

ADCIntClear(ADC0_BASE, 0);
}

uint32_t ADCValue;

void
ConfigADC(void)
{

SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);

SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE);

ADCReferenceSet(ADC0_BASE, ADC_REF_INT);

GPIOPinTypeADC(GPIO_PORTE_BASE, GPIO_PIN_3);

ADCSequenceConfigure(ADC0_BASE, 0,

ADC_TRIGGER_TIMER, 0);

ADCSequenceStepConfigure(ADC0_BASE, 0,
0, ADC_CTL_CH0 | ADC_CTL_IE | ADC_CTL_END);

ADCIntRegister(ADC0_BASE, 0, ADCIntHandler);

ADCSequenceEnable(ADC0_BASE, 0);

ADCIntClear(ADC0_BASE, 0);
}

void
ADCRead(void)
{
TimerControlTrigger(TIMER0_BASE, SysCtlClockGet() / 1000, true);

while(!ADCIntStatus(ADC0_BASE, 0, false))
{
}

ADCIntClear(ADC0_BASE, 0);

TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

ADCSequenceDataGet(ADC0_BASE, 0, &ADCValue);

}

int main()

{

SysCtlClockSet(SYSCTL_SYSDIV_2_5 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);

ConfigTimer();

ConfigADC();

SysCtlPeripheralClockGating(true);

SysCtlLDOSleepSet(SYSCTL_LDO_1_15V);

SysCtlSleepPowerSet(SYSCTL_SRAM_STANDBY);

while(1)

{

// Read ADC every 1ms
ADCRead();

}

}

Hello Moz,

Thanks for the code

Suggestion-1 Replace

while(!ADCIntStatus(ADC0_BASE, 0, false))
{
}

ADCIntClear(ADC0_BASE, 0);

with

SysCtlSleep

Suggestion-2: remove the following as that is being done in the Timer Interrupt Handler

TimerIntClear(TIMER0_BASE, TIMER_TIMA_TIMEOUT);

Suggestion-3: Move this to the ADC Interrupt Handler

ADCSequenceDataGet(ADC0_BASE, 0, &ADCValue);

Suggestion-4: Add this to the ADC Initialization as well

SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_ADC0);

Hello Amit,

I was looking this old post because I want to get 1KHz of sampling frequency of ADC and I wanto to ask you some clarifitications about it.

1) Why it's no necessary to use

while(!ADCIntStatus(ADC0_BASE, 3, false))

{ } ADCIntClear(ADC0_BASE, 3); ??

2) Why the instruction ADCSequenceDataGet() has to be in ADCO Interrupt Handler insteaod of in the while(1)?

3) To get 1KHz of frequency, if ui32freq=SysCtlGet()=50MHz, I have to put n=5000 in

TimerLoadSet(TIMER0_BASE, TIMER_A, ui32freq / n);, right?

4) Is it wrong put SysCtlSleep() after the data acquisition, in this way: 

 ConfigTimer();

while(1)

{  TimerControlTrigger(TIMER0_BASE, SysCtlClockGet() / 1000, true);

ADCProcessorTrigger(ADC0_BASE, 3);

 while(!ADCIntStatus(ADC0_BASE, 3, false))

{ }

ADCIntClear(ADC0_BASE, 3);*/

ADCSequenceDataGet(ADC0_BASE,3,&ADC0Value);

ADC_Val[i]=ADC0Value;

SysCtlSleep();

i++;

}

I am using Tiva C Launch Pad TM4C123G. ConfigTimer() is the same used by Moz.

Thank you for any help you can provide.

But  to get 1KHz of sampling frequency, I need to use only the timer interrupt, it's not necessary to put ADC in sleep mode, right?

Thanks Amit for replying,

I have got a small query. I have generated an interrupt bt is there any function which I need to call so that device can come out of sleep mode?