TIMER1->INTENSET cause a ble connection drop problem.

[shadow]

Hi,

I want to use timer1 or 2 interrupt ISR to generate complicated PWM signal. but the timer->intenset setting cause ble connection drop problem.

Please refer to my code below.

NRF_TIMER2->MODE      = TIMER_MODE_MODE_Timer;
NRF_TIMER2->BITMODE   = TIMER_BITMODE_BITMODE_16Bit << TIMER_BITMODE_BITMODE_Pos;
NRF_TIMER2->PRESCALER = 9;

// Clears the timer, sets it to 0.
NRF_TIMER2->TASKS_CLEAR = 1;

// Load the initial values to TIMER2 CC registers.
NRF_TIMER2->CC[0] = 10000;

// Interrupt setup.
*NRF_TIMER2->INTENSET = (TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos);*


// Enable interrupt on Timer 2.
//NVIC_EnableIRQ(NRF_TIMER2);

// Start the timer.
NRF_TIMER2->TASKS_START = 1;	

if I comment out the TIMER2->INTENSET, then no problem.

Please let me know why...

Best regards, Joy Kang.

[Susheel Nuguru]

If you have not set the priority of this IRQ then it is by default running at highest priority which BLE softdevice will not accept. This is because only SD is allowed to used the highest priority interrupts. Set priority of your timer to APP_PRIORITY_LOW or APP_PRIORITY_HIGH. The timing of your PWM signal will be affected with BLE activity as your interrupt execution might be delayed and it depends totally on the BLE activity.

[shadow]

Connection drop problem was caused by Unstable LFCLK. After adjust LFCLK(32768), connection drop problem is disappeared But the TIMER2 capture interrupt is missed some time, so It is impossible to make guaranteed 250us ISR for PWM. Is there anyway to make 250us ISR without delay or missing.

Best regards, Joy Kang.

[Susheel Nuguru]

No, it cannot be guarenteed (infact, it is not possible) if your PWM signal depends on the interrupt service and while BLE activity. SDK PWM library in SDK uses PPI, TIMERS and GPIOTE to make hardware connections so that its timing does not depend on any ISR.