Increased Peak Advertising Current

[Justin]

While advertising I could see some increased current peaks on one of the three channels. Its random and is observed mostly at the first or last channel of advertising.

Any idea what could be the reason? Does the nearby scanning device affect the power consumption? I am using nordic nrf52832 chip. 

Attached are some screenshots that show an advertising sequence where I captured 3 larger peaks along with zoomed in views of each of those larger peaks.

[Kenneth]

Hi,

This is likely a central that is transmitting a scan request packet, and then the peripheral will reply with a scan response packet. This typically happen on 1 of the advertisement channels, but may also happen on more than 1 channel if there are more than 1 central nearby.

Best regards,
Kenneth

[Justin]

Kenneth said:

This is likely a central that is transmitting a scan request packet, and then the peripheral will reply with a scan response packet. This typically happen on 1 of the advertisement channels

Putting my setup into the anechoic chamber did eliminate the occasional larger advertising current peaks.

As a result, the larger peaks do appear to be linked to some device behavior related to scan requests coming from central devices.

 

But in that case I would expect a longer period of a Tx --> Rx --> Tx --> Rx current draw rather than a higher current draw.

Is my understanding correct?

[Justin]

Hi Kenneth,

We captured 3 screenshots using the same scale that shows a normal advertising current pulse, the slightly higher pulse that we saw before which we associated with the scan response, and the new higher amplitude pulse that we observed and don’t know what it is.

We see the higher amplitude pulse occur during the channel 37 activity. With the Ellisys BLE sniffer, it does not appear that this is linked to a scan response.

Is there anything that we are not counting for?

[Kenneth]

Hi,

It may also be an invalid BLE packet from a central device (e.g. scan request packet with CRC errors due to interference and/or a connection request packet CRC with errors), in these cases the radio may stay in receive mode until a timeout occurs.

Best regards,
Kenneth

[Justin]

Thanks Kenneth for the clarification.