| Mynewt FAQ - Hardware-Specific Questions |
| ======================================== |
| |
| .. contents:: |
| :local: |
| :depth: 2 |
| |
| Nordic nRF52-DK |
| --------------- |
| |
| Inverted Pin Value on nRF52-DK |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| **Q**: I’ve been experiencing what seems to be some oddities with ``hal_gpio_write``. It appears as though the LED |
| pin value on the nRF52-DK is inverted (0 sets the pin high, 1 sets it low). I am checking the GPIO state by turning |
| an LED on and off. Why is this the case? |
| |
| **A**: LEDs on the nRF52-DK are connected to VDD and GPIO so you need to set GPIO to a low state in order to make it turn on. |
| |
| Time Precision on nRF52 |
| ~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| **Q**: Can ``OS_TICKS_PER_SEC`` be changed per app? I'm on the nRF52 and I need better time precision than 128Hz. |
| |
| **A**: No, it isn't possible to change the ticks per second for a single app. That constant is defined to be most efficient |
| for the particular MCU. |
| |
| If you need precision, the OS tick timer is probably not the right thing to use. Take a look at :doc:`OS CPU Time <../../../../os/core_os/cputime/os_cputime>` for timer documentation. ``os_cputime`` has 1MHz frequency by default, and is enabled by default. |
| It is recommended to use this for higher precision applications. |
| |
| Size Limit on Transaction Length for nRF52 |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| **Q**: There appears to be a 256-byte size limit on the maximum transaction length that the nRF52xxx ``hal_i2c`` driver can support. When I try send transactions larger than this the transactions fail (even after playing with a larger timeout etc). Does anyone know if this limit is due to the way the driver is written or the nRF52's i2c peripheral itself? |
| |
| **A**: There shouldn’t be any limit here since TWI works basically by transferring data byte after byte. Check your slave device to see if it has some limit. |
| |
| Redbear BLE Nano 2 |
| ------------------ |
| |
| View Logs on the Redbear BLE Nano2 |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| **Q**: Is it possible to see debug statements / logs while using Mynewt on the Redbear BLE Nano2. If so, can someone please |
| tell me how to do so? |
| |
| |
| **A**: The RedBear daplink board presents multiple USB devices, one is a serial port which you can connect to. The |
| :doc:`Blinky example project <../../tutorials/blinky/rbnano2>` has debug log statements which you can look at for how to log. |
| |