How to change the internal capacity of XOSC32MCAPS

[Summer.Xu]

Now we don't add the external capacitance and want to change the  internal capacitance . I have install the test tool and send the command to write the register,but it seems fail ,how to write it succesfully?

 

[Bendik Heiskel]

Hi,

Is the chip being power cycled between the write and read?

If there is FW running on the device it will rewrite the register on boot to the value specified in the FW.

The internal capacitors can be configured in the application using the kconfig options:

CONFIG_SOC_HFXO_CAP_INTERNAL

CONFIG_SOC_HFXO_CAP_INT_VALUE_X2

 

Best regards,

Bendik

[Summer.Xu]

Hi ，

Thanks for your reply.

We just want to use the J-Link tool to modify the capacitors to find the appropriate value . We don't make the power cycle when we do the test.Now I had install the 'nrf-command-line-tools' .If we want to set the internal capacitors to be 0, which command could use? And waht is the test step？

Looking forward the reply~Thanks.

[Bendik Heiskel]

Is there any application flashed to the chip?

Try to recover both the network and application cores, and then write to the XOSC32MCAPS register.

The network core must be recovered first using:

nrfjprog --coprocessor CP_NETWORK --recover

And then the application core can be recovered using:

nrfjprog --recover

Summer.Xu said:

If we want to set the internal capacitors to be 0, which command could use?

Do you want to disable the capacitors? Setting the register to 0 will disable them. If you want to set the capacitance to the lowest value you must write 0x100 to the register.

You are using the correct command for writing to the register.

Summer.Xu said:

And waht is the test step？

To test the crystal oscillating frequency its best to use a constant carrier output from the radio and measure the frequency offset using a spectrum analyzer.

To enable a constant carrier at 2.44GHz using nrfjprog you can use these commands in this order:

nrfjprog --coprocessor CP_NETWORK --memwr 0x41008508 --val 40 
nrfjprog --coprocessor CP_NETWORK --memwr 0x4100850C --val 0xFD
nrfjprog --coprocessor CP_NETWORK --memwr 0x41005000 --val 1
nrfjprog --coprocessor CP_NETWORK --memwr 0x41008000 --val 1 

 

Best regards,

Bendik