Design_World_-_Internet_of_Things_Handbook_April_2020

eeworldonline.com | designworldonline.com 4 • 2020 DESIGN WORLD — EE NETWORK 37

The combination of sophisticated hardware and

powerful software enables application developers to

perform their own benchmarking on multiple devices.

This is the recommended approach that should be

taken before selecting a BLE SoC. While initially more

time consuming, this approach proves to be extremely

valuable and helps reveal hidden challenges resulting

from either missing hardware features or non-optimal

software capabilities.

The development of a standardized benchmarking

strategy can also help developers compare devices

from multiple suppliers. The IoTMark-BLE benchmark

profile developed by the Embedded Microprocessor

Benchmark Consortium (EEMBC) provides a useful tool

for assessing power consumption. The IoTMark-BLE

benchmark profile models a real-world IoT edge node

consisting of an I2C sensor and a BLE radio through

sleep, advertise and connected-mode operations.

While this IoTMark-BLE benchmark might not suit

all use cases, it can serve as a foundation for developing

appropriate scenarios for any given application.

In a nutshell, side-by-side comparisons of vendor

datasheets can lead to costly misunderstandings and

misrepresentations. The analysis of BLE SoCs must take

place at a system level as illustrated when comparing

on-board and external dc-dc converter blocks within an

SoC. Third-party benchmarks can often help determine

what the comparative analysis should look like.

EFR32BG22 typical application

without dc-dc converter

Main
supply

VDD

CDECOUPLE

VREGVDD AVDD IOVDD

VREGSW

VREGVSS

DVDD

DECOUPLE

RFVDD PAVDD

HFXTAL_I

38.4 MHz

32.768 kHz

(optional)

HFXTAL_O

LFXTAL_1

LFXTAL_O

VDD

EFR32BG22 typical application

using dc-dc converter

Main

supply

VDD

VREGSW

VREGVSS

DVDD

DECOUPLE

RFVDD PAVDD

HFXTAL_I

38.4 MHz

32.768 kHz

(optional)

HFXTAL_O

LFXTAL_1

LFXTAL_O

CIN

VREGVDD AVDD IOVDD

VDCDC

CDCDC

LDCDC

CDECOUPLE

The EFR32BG22 is an example of an BLE SoC that incorporates

an on-chip dc-dc converter. Using the dc-dc converter will

significantly reduce the active current consumption of the entire

SoC. Some sophisticated SoCs may integrate separate dc-dc

converters for the radio and for the CPU. This practice provides

an optimized solution, but the trend is clearly to have only one

converter to minimize the cost of the SoC.

References

The EFR32BG22 datasheet:

https://www.silabs.com/wireless/

gecko-series-2/efr32bg22

The IoTMark-BLE benchmark:

https://www.eembc.org/iotmark/

Mark Orchard-Webb, Silicon Labs,

contributed the software enablement

paragraph in this article.

SELECTING BLE SoCS