BK3231S Datasheet

V1.5

© 2015 Beken Corporation

Proprietary and Confidential

Page 17 of 24

3.2 Interrupt and Clock Unit

The MCU core clock can be selected from three clock sources: 32KHz clock, 16

MHz clock and 96 MHz DPLL.

The ARM968E-S supports two interrupt level. The FIRQ has higher priority than

nIRQ. In the BK3231S, all peripheral interrupts are nIRQ except the Bluetooth

transceiver. All interrupt can be enabled, disabled, and cleared. There are two

low power modes: MCU stop and deep sleep, and any interrupt can be

configured to be a wake up source to let MCU exit low power mode.

3.3 GPIO

There are totally 40 general purpose input/output ports (GPIO). All the 40 ports

can be used for general I/O with selectable direction for each bit, or these lines

can be used for specialized functions.

3.4 ADC

An 8bits SAR-ADC is integrated in the BK3231S. Total 8 channels can be

selected used for ADC transfer. The ADC supports continue mode and single

transfer mode, and the sample rate can be 1 KHz to 32KHz. In single transfer

mode, it will generate interrupt every time after transform.

The ADC has four work modes they are sleep mode, single mode, and software

mode and continue mode.

IDLE mode(mode==00): ADC is in idle state.

Single mode(mode==01): The ADC will enter idle mode when transfer is done

and waiting MCU to read the result. You should write mode=1 again for another

transfer.

Controlled by software (mode==10): In this mode, interrupt will be triggered after

transfer and wait MCU to read. The interrupt will be cleared after MCU read, and

then the transfer will start again.

Continue mode(mode==11):The ADC will work at the sample rate set by register.

The sample rate can be calculated by the next formula:

F_sample = input ADC clock/(2^(ADC_CLK_RATE+2) / 36(or 18))

The highest sample rate is 32k