nRF52832, ports/GPIOs x internal peripherals, ports/GPIOs x wakeup from sleep, plus general HW doubts

[Abomin3v3l]

Hi.

In my current project with nRF52832, I have used the following port pins to connect it to an accelerometer and a SPI flash memory:

I would like to ask, get opinions about:

(1) If all internal signals of all serial peripherals like SPIs, I2Cs and UARTS can be configured in firmware to be connected to any port/GPIO pin.

(2) If any port/GPIO pin can be used to wakeup the MCU from sleep mode through logic level changes on the pins.

(3) The number of SPI peripherals? The number of I2C peripherals? The number of UART peripherals? And if they are shared? This is for future designs.

(4) If the schematic above is ok, regarding the 4-wire SPI signals of the 2 SPIs interfaces being connected to the nRF52832 pins P0.11~P0.14 and P0.17~P0.20, and if the INT1/INT2 push-pull outputs of the accelerometer which are connected to P0.15 and P0.16 can wakeup the nRF52832 from sleep mode through logic level changes on these pins.

(5) By connecting the two SPI interface signals to the pins shown in the schematic above I'm following the recommendation from the nRF52832 Product Specification (shown below), which recommends the use of signals <=10KHz for ports P0.22 to P0.31, that are nearby radio signals or related. Actually all these pins are not used in my current design.

(6) P0.25 and P0.26 were connected to GND as a workaround, this was recommnded to me by Nordic support in past.

(7) What is the positive reference of the analog inputs / ADC? That is, for which input voltage the ADC result will have its maximum value? And what is the resolution (bits) of the ADC?

(8) In which situations is really needed the use of an external 32.768KHz crystal oscilator? Please correct me if I'm wrong with such statement: the nRF52832 has an internal "not-high-precision-low-frequency-oscillator" which can be used by its internal RTC to wakeup the MCU from sleep periodically or in a predefined interval/period/seconds/minutes/hours to ahead.

Regards,
Jeferson Pehls.

[Simonr]

Hi Jeferson

Yes, any of the pins marked as GPIOs, or "Px.xx" can be used to for example generate interrupts from logic level changes.

Best regards,

Simon

[Abomin3v3l]

Hi Simon.

The nRF52832 have 3x RTC (real-time counter).

Is it possible to implement a basic RTC (real-time 'clock') making a basic horary/calendar function? In the case of our first project with the 52832 we will use the internal 32.768KHz crystal oscillator.

Do you know that time scheme that count seconds passed since the start of 1970? How about if the nRF52832 receives via BLE such number of seconds, and activates a timer that generates an interrupt every 1 second, and then increment in 1 the value of seconds since the start of 1970? Consider that with some frequency the MCU would receive an updated value via BLE, because as the clock that runs the timer is not so accurate, with time there would be a lag.

Regards.