CC1352P: power consumption by sensor controller polling ADC at 256Hz lower than specified in SWRA578B

Hi,

According to SWRA578B, polling ADC (light sensor) at 10Hz by sensor controller adds 10uA to overall system power consumption. But I when I tried to poll 4-channel ADC (one connected to VCC, one connected to GND, another 2 floating) at 256Hz, the measured power consumption via EnergyTrace++ only increased about 15uA compared to no ADC polling. Apparently this is not much higher than the specified 10uA at 10Hz.

My questions are:

1) Does this the 10uA@10Hz figure in SWRA578B include power consumption of light sensor itself?

2) Could be there some something wrong in my test code that sensor controller is not really polling at 256Hz?

The code to poll ADC is mostly adapted from the Multi Channel ADC Sampling for LaunchPad project shipped with sensor controller. Once a total of 256 samples are collected for each channel, application MCU is alerted. Judging by the numbers for the channel that are connected to VCC or GND, at least I can confirm that indeed 256 samples are collected. My suspicion is that polling 4 channel at 256Hz may take longer than 1 second, therefore the effective polling rate is not as high.

3) The frequency of task execution is controlled by the following line of code in application:

// Execute once every X seconds

scifStartRtcTicksNow((655360/10)/* 1 second */ * 1 /* X */);

 

Is my calculation wrong?

Please advise, thanks.

ZL

On a side, somehow I cannot insert code in posts.