Hello all,
This is my first project using Nordic chips and my first project using BT. A lot of firsts :)
I have made a custom board using nRF52820 chip. The board is 4 layer 0.8mm thick board 80mm x 50mm. I have used the PCB manufacturer's calculator to set the trace with for the 50 ohm impedance. The antenna I am using is Johanson Technology 2450AT43A100E. I do not have low frequency xtal on the board. You can see may schematics and the layout I have used for this board bellow.
Layout
Schematic
I am programming the board using nRF52833-DK. So far I got SPI, TWI and USB to work on the board, but I am struggling with the RF part.
For my base project I am using the "usbd_ble_uart". I can successfully connect and RX/TX data using my phone and the DK. I have looked at questions already posted on the forum and I figured out that I need to change the LF clock source to the internal RC oscillator. The changes I have made to the "sdk_config.h" files are the following. SoftDevice version is s140 and the SDK is v17
#ifndef NRFX_CLOCK_CONFIG_LF_SRC #define NRFX_CLOCK_CONFIG_LF_SRC 0 #endif #ifndef CLOCK_CONFIG_LF_SRC #define CLOCK_CONFIG_LF_SRC 0 #endif // <o> NRF_SDH_CLOCK_LF_SRC - SoftDevice clock source. // <0=> NRF_CLOCK_LF_SRC_RC // <1=> NRF_CLOCK_LF_SRC_XTAL // <2=> NRF_CLOCK_LF_SRC_SYNTH #ifndef NRF_SDH_CLOCK_LF_SRC #define NRF_SDH_CLOCK_LF_SRC 0 #endif // <o> NRF_SDH_CLOCK_LF_RC_CTIV - SoftDevice calibration timer interval. #ifndef NRF_SDH_CLOCK_LF_RC_CTIV #define NRF_SDH_CLOCK_LF_RC_CTIV 16 #endif // <o> NRF_SDH_CLOCK_LF_RC_TEMP_CTIV - SoftDevice calibration timer interval under constant temperature. // <i> How often (in number of calibration intervals) the RC oscillator shall be calibrated // <i> if the temperature has not changed. #ifndef NRF_SDH_CLOCK_LF_RC_TEMP_CTIV #define NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 2 #endif // <o> NRF_SDH_CLOCK_LF_ACCURACY - External clock accuracy used in the LL to compute timing. // <0=> NRF_CLOCK_LF_ACCURACY_250_PPM // <1=> NRF_CLOCK_LF_ACCURACY_500_PPM // <2=> NRF_CLOCK_LF_ACCURACY_150_PPM // <3=> NRF_CLOCK_LF_ACCURACY_100_PPM // <4=> NRF_CLOCK_LF_ACCURACY_75_PPM // <5=> NRF_CLOCK_LF_ACCURACY_50_PPM // <6=> NRF_CLOCK_LF_ACCURACY_30_PPM // <7=> NRF_CLOCK_LF_ACCURACY_20_PPM // <8=> NRF_CLOCK_LF_ACCURACY_10_PPM // <9=> NRF_CLOCK_LF_ACCURACY_5_PPM // <10=> NRF_CLOCK_LF_ACCURACY_2_PPM // <11=> NRF_CLOCK_LF_ACCURACY_1_PPM #ifndef NRF_SDH_CLOCK_LF_ACCURACY #define NRF_SDH_CLOCK_LF_ACCURACY 1 #endif
But still I cannot connect with phone to the custom board. I cannot see it listed in the BT devices at all.
How can I determine if it is a software or a hardware issue? Is there something else I need to change to the config? I have read the post for migrating code to the nRF52820 and yes the preprocessor directives are set correct and the memory sizes are adjusted.
There are a lot of logging options set up in the examples, is any of it going to be useful?
As tools go I have a scope but unfortunately I do not have a spectrum analyzer at my disposal.
If there is example specially made for the nRF52820 would be great! This way I could see if it is my design to blame or just some tricky config.
All the best,
Mitko
