9 years, 1 month ago.

What are the mystery writes at the beginning of the nRF51822 BLE example programs?

Both the BLE_Beacon and BLE_HeartRate examples start with the uncommented mystery register writes:

    *(uint32_t *)0x40000504 = 0xC007FFDF;
    *(uint32_t *)0x40006C18 = 0x00008000;

Yet looking in the nrf51822 family reference manual I can't find these registers.

The first one should be in the CLOCK or POWER peripheral; the second one in the GPIOTE peripheral.

What are these?

Question relating to:

The nRF51822-mKIT is a low cost ARM mbed enabled development board for Bluetooth® Smart designs with the nRF51822 SoC. The kit gives access to all GPIO pins via pin headers …

Where did you find the example programs? Are these from Nordic? (I don't see any BLE examples on mbed)

posted by Mike Tomovich 16 Apr 2014

1 Answer

9 years, 1 month ago.

These writes are to setup some specific registers in case people are using older revisions of the nRF51822 chips, just to make sure they have a known value. Some early silicon didn't set certain registers to the same value, and Nordic suggested adding the code above as a work-around.

As per the examples, you can find some examples in the BLE Team page here: https://mbed.org/teams/Bluetooth-Low-Energy/

To add to Kevin's answer - The mystery registers should be documented in the nRF51822 Product Anomaly Notification (PAN) sheet found on the Nordic website. http://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822

Looks like this is being moved into the mbed library startup code so it may disappear soon https://github.com/mbedmicro/mbed/blob/master/libraries/mbed/targets/cmsis/TARGET_NORDIC/TARGET_NRF51822/system_nrf51822.c#L45

posted by Sam Grove 16 Apr 2014