Port manipulation Arduino Nano 33 BLE

sebastian1986 · June 10, 2021, 8:12pm

Hi,

i would like to use direct port manipulation on the nano 33 BLE.

Background: I have several digitalWrite() within a timer callback function. This takes too much time and hence i need to speed up / optimise the code.

The commands PORTD or DDRD (see pic) seem to not work on the 33 BLE architecture. Is there any equivalent - i guess so!?

Thanks a lot!

PieterP · June 10, 2021, 9:13pm

You can have a look how it's done in Mbed OS:

github.com

ARMmbed/mbed-os/blob/a3be10c976c36da222517abc0cb4f81e88ff8552/targets/TARGET_NORDIC/TARGET_NRF5x/gpio_object.h#L32-L39

    
      
          static inline void gpio_write(gpio_t *obj, int value) {
              MBED_ASSERT(obj->pin != (PinName)NC);
              if (value) {
                  nrf_gpio_pin_set(obj->pin);
              } else {
                  nrf_gpio_pin_clear(obj->pin);
              }
          }

Klaus_K · June 12, 2021, 2:50am

That is the problem with low level code. It is not portable.

Can you tell us a bit more what your application is doing? That might give use some ideas how you can solve your issue.

profrob · June 13, 2021, 6:57am

Look at the data sheet (product specification) of the nRF52840 (available at Nordic). You can access the registers directly via pointers to the periphery modules (here GPIO). Because all ARM micro-controllers are rather similar, you can learn also from Arduino Due (SAM3x, Cortex M3) or Arduino Zero (SAMD21, Cortex M0).
There are different registers for setting and resetting pins. So you can use the same mask for setting/resetting a pin or a group of pins.
But you may get problems, if you use the mbed-OS (e.g. if you run the ArduinoBLE library).
Till now, I had no problems with direct nRF52840 access in loop() without the ArduinoBLE library. With the BLE library I detected delays up to 5 milliseconds.
Good luck.