nRF51822 Bit-Width and BITMODE

[Paul]

Hello,

Firstly, the nRF5122 Product Specification v1.3 Section 4.2 says that TIMER0 is 32 bits wide. However, other product specs seem to mention 16/24 bit timers, and it seems to be 24 bits.

Secondly, changing the BITMODE register does not seem to change the frequency of a compare interrupt.

NRF_TIMER0->BITMODE = TIMER_BITMODE_BITMODE_08Bit;

Paul.

(for the code below, interrupt still happens once per second)

NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
NRF_CLOCK->TASKS_HFCLKSTART = 1;

while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
	
NRF_TIMER0->MODE = TIMER_MODE_MODE_Timer;
NRF_TIMER0->PRESCALER = 0;
NRF_TIMER0->BITMODE = TIMER_BITMODE_BITMODE_08Bit;

NRF_TIMER0->TASKS_CLEAR = 1;

NRF_TIMER0->CC[0] = 10;	

NRF_TIMER0->INTENSET =
	(TIMER_INTENSET_COMPARE0_Enabled << TIMER_INTENSET_COMPARE0_Pos);

NVIC_EnableIRQ(TIMER0_IRQn);
	
__enable_irq();

NRF_TIMER0->TASKS_START = 1;

[Håkon Alseth]

Hi,

This is unfortunately a bug with the current revision of the nRF51x22 silicone. The BITMODE field is non-functional. This is explained more in detail in this document: www.nordicsemi.com/.../3334310

One thing to take note of is that the reference manual specifies the series, while the product specification specifies the limitations of the device within the series. The nRF51x22 doesn't have a 32 bit timer, unfortunately.

Best regards Håkon

[Paul]

Thanks, I hadn't seen that document, so I'm glad I have it now! I notice that some of the TIMER errata seem to apply to the RTC as well.

I referred to the product specification in my initial question, so perhaps it needs changing to not mention a 32 bit timer.

[nospam2000]

The linked document is no longer available. Which document are you referring to?