8.1 Example Calculations

This section helps the user in estimating the average power consumption for the sleeping device in their network. This scenario includes an actual measurement to understand the deviation between the estimated and measured value. The user can do this by determining the typical events that the node can encounter in its lifetime and estimating the power consumed based on the power consumption measurements done in this application note.

The following example scenario explains the steps involved in estimating the average power consumption for a sleeping device node in a Mi-Wi Star topology:
  1. Sleeping device initializes and sends a P2P connection request and scans for a connection response
  2. Sleeping device sends an indirect data request every 120 seconds
  3. Sleeping device sends a link status every 120 seconds
  4. Sleeping device sends application data every 120 seconds

The following example estimates the power consumption for a one-hour duration. Within this duration, the sleeping device completes the connection to the nearby P2P device, 60 data requests and 30 link status. The following table helps in estimating the average power consumption for the device in the chosen measurement duration.

Table 8-1. Measurement Duration
Total measurement duration (ms) 3600000
Table 8-2. SAM R30 XPro
Scenario Estimated Number of Instances Single Instance Duration (ms) Measured Total Duration (ms) Measured Average Current (mA) Estimated Average Charge Consumed (mA*ms)
Initialization 1 153.14 153.14 1.74 266.4636
P2P connection request and response 1 28.8 28.8 12.34 355.392
Scan duration 1 1959 1959 10.45 20471.55
App data 30 140 4200 11.16 46872
Periodic indirect data request 30 50.9 1527 9.02 13773.54
Periodic indirect data request with link status 30 60.7 1821 9.76 17772.96
Estimated total charge consumption (excluding Sleep) — — — — 99511.9056
Table 8-3. SAM R30 Module XPro
Scenario Estimated Number of Instances Single Instance Duration (ms) Measured Total Duration (ms) Measured Average Current (mA) Estimated Average Charge Consumed (mA*ms)
Initialization 1 125.6 125.6 1.73 217.288
P2P connection request and response 1 31 31 12.8 396.8
Scan duration 1 1935 1935 10.55 20414.25
App data 30 12 360 12 4320
Periodic indirect data request 30 50.9 1527 9.981 15240.987
Periodic indirect data request with link status 30 60.5 1815 11.1 20146
Estimated total charge consumption (excluding Sleep) — — 5668 — 60518.537
Table 8-4. Estimated Charge Consumption Calculations for Sleep
Parameters SAM R30 XPro SAM R30 Module XPro
Measured sleep current (mA) 0.00186 0.00176

Estimated total sleep duration (ms) (Total measurement duration - Sum of measured total duration)

 3590311.06 3594332
Estimated total sleep charge consumption (mA*ms) 6677.978572 6326.02432
Table 8-5. Estimated Total Charge and Current Consumption
Parameters SAM R30 XPro SAM R30 Module XPro
Estimated total charge consumption (including Sleep) 106189.8842 66844.56132
Estimated total average current consumption (mA) 0.02949719 0.018567934
The following example scenario explains the steps involved in estimating and measuring the average power consumption for a sleeping device node in a Mi-Wi Star topology:
  1. Sleeping device initializes and sends the P2P connection request and scans for the connection response
  2. Sleeping device sends the indirect data request every 8 seconds
  3. Sleeping device sends the link status every 15 seconds

The following example uses an arbitrary measurement duration of 17.152 seconds and, within this duration, the sleeping device would have completed the connection to the nearby P2P device and one indirect data request with link status. The following table helps in estimating the average power consumption for the device in the chosen measurement duration:

Table 8-6. Measurement Duration
Total measurement duration (ms) 17152

The following are the estimated charge consumption calculations for scenarios except sleep.

Table 8-7. SAM R30 XPro
Scenario Estimated Number of Instances Single Instance Duration (ms) Measured Total Duration (ms) Measured Average Current (mA) Estimated Average Charge Consumed (mA*ms)
Initialization 1 153.14 153.14 1.74 266.4636
P2P connection request and response 1 28.8 28.8 12.34 355.392
Scan duration 1 1959 1959 10.45 20471.55
Periodic indirect data request 1 50.9 50.9 9.02 459.118
Periodic indirect data request with link status 1 60.7 60.7 9.76 592.432
Estimated total charge consumption (excluding Sleep) — — — — 22144.9556
Table 8-8. SAM R30 Module XPro
Scenario Estimated Number of Instances Single Instance Duration (ms) Measured Total Duration (ms) Measured Average Current (mA) Estimated Average Charge Consumed (mA*ms)
Initialization 1 125.6 125.6 1.73 217.288
P2P connection request and response 1 31 31 12.8 396.8
Scan duration 1 1935 1935 10.55 20414.25
Periodic indirect data request 1 9.02 9.02 50.9 459.118
Periodic indirect data request with link status 1 9.76 9.76 60.5 590.48
Estimated total charge consumption (excluding Sleep) — 2110.38 — — 22077.936
Table 8-9. Estimated Charge Consumption Calculations for Sleep
Parameters SAM R30 XPro SAM R30 Module XPro
Measured Sleep current (mA) 0.00186 0.00176

Estimated total Sleep duration (ms) (Total measurement duration – Sum of measured total duration)

 14899.46 15041.62
Estimated total Sleep charge consumption (mA*ms) 27.7129956 26.4732512
Table 8-10. Estimated Total Charge and Current Consumption
Parameters SAM R30 XPro SAM R30 Module XPro
Estimated total charge consumption (including Sleep) 22172.6686 22104.409251
Estimated total average current consumption (mA) 1.292716219 1.2887365468
Table 8-11. Measured Current Consumption
Parameters SAM R30 XPro SAM R30 Module XPro
Measured total average current consumption (mA) 1.23 1.24

When the total duration increases, the maximum component of current consumption can only be Sleep, which would result in a lower average current consumption as such.