Higher peripheral peak current for write command compared to write request?

[Fredrik]

Hi,

I am trying to understand the current consumption of a very simple BLE application running on the nRF52832 DK. For my final use case, I'd like to reduce the peak current draw of my BLE application as much as possible.

The application is based on the ble_app_template application, with an added dummy service and a dummy characteristic. The dummy characteristic has the write and write_wo_resp properties set. I also have a central device which connects and writes data to the dummy characteristic continuously. The modified ble_app_template code is attached to this post somewhere. Note that i am using gcc to compile the example.

When probing with the PPK, I noticed that the peak current draw in my peripheral, when receiving a write command, is just over 17.8 mA. For write requests, however, I observe a peak current draw of 12.6 mA. See images below.

I had a look in the BLE spec around Vol 3, Part F on the Attribute Protocol, as well as a search through the devzone forums, but I could not spot any obvious reason for this behavior.

Maybe you can shed some light on this. Any help is greatly appreciated.

/cfs-file/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-e21bdf58eac040adba832d0214af2811/ble_5F00_app_5F00_template_5F00_source.zip

Best,

Fredrik

[Andreas]

Hi,

 

This adds quite well up to the CPU being active at the same time, unfortunately there is not really any way to avoid that. The only way to reduce the peak current is to lower TX output power (TX only obviously) and use the DCDC regulator mode of the power supply.

 

Best regards,

Andreas

[Fredrik]

Hi Andreas,

Thanks for clarifying. Do you know why the CPU might be active at the same time as the RADIO module for write commands, but not for write requests?

Best,

Fredrik