Powerscale - Frequently Asked Questions
1. What is PowerScale?
PowerScale is an energy profiling tool that is used to optimise the power consumption of your embedded application. PowerScale relates the power consumption of the microcontroller to regions of application code as it runs. PowerScale measures real power consumption by measuring current and voltage simultaneously. PowerScale can measure and display four different power domains simultaneously.
2. Why use PowerScale?
Designing energy efficient products is becoming an important factor for many embedded systems. While extended battery life for hand-held products is constantly being improved, many other types of application areas such as automotive and industrial are being forced to address their power consumption in order to reduce CO2 emissions. PowerScale has been designed specifically for embedded software developers. PowerScale allows you to easily visualise the power requirements of your application and relate it back directly to the code running on the microcontroller.
3. How does PowerScale work?
PowerScale is composed of a System Box and up to four measurement probes. The PowerScale System Box is connected via USB to the PC and via flat, flexible cable to the probes. A minimal system comprises the PowerScale System Box and one PowerScale Probe. Each probe can be connected to a different power domain and simultaneously samples voltage and current for true power measurement. Multiple probes are synchronised by the System Box so all measurements are made simultaneously. Each probe supports a maximum sample rate of 100Ksamples/sec. Additionally, each probe can monitor trigger events driven by the application software. This allows PowerScale to display the power consumption of selected regions of code. The Trigger events can come from simple IO, microcontroller UART or supported debuggers. PowerScale can be used with any microcontroller. PowerScale is delivered with its own easy to use GUI. An open API is also provided so the PowerScale unit can be incorporated into custom debug and testing environments.
4. How can PowerScale help to reduce power consumption of a system?
PowerScale is a tool for analysing power usage and optimizing energy profiles of embedded applications. PowerScale has been specifically designed for embedded system developers who need to reach the optimal power consumption for their application. By using PowerScale as part of your design cycle you can easily characterise the power consumption of a given system, quickly isolate energy hungry regions of code and spot hardware and software flaws.
5. Does PowerScale only work on special hardware or evaluation kits?
No, PowerScale is a general purpose energy profiling and optimizing tool for every system, independent of microcontroller architecture or supplier.
6. How can I detect which part of the application software consumes power?
PowerScale relates the power usage of the target system by receiving trigger information from the target application. Triggers are used to tell PowerScale which region of code is running. The region information is displayed on the line graph. A pie chart also displays the energy usage of the code regions as a percentage of the overall power requirement. The code regions are user defined and microcontroller independent. Each of the PowerScale Probes has its own independent trigger logic. Triggers may be provided from the following sources: Microcontroller IO pins: simple toggling of an IO pin can denote entry/exit to a code region Microcontroller UART: a serial protocol over a standard UART can provide region information Microcontroller Debug Hardware: microcontrollers capable of providing ‘on the fly’ debug information through supported debuggers. For example Cortex-M3 microcontrollers using the Instrumentation Trace (ITM) can provide custom code region information to PowerScale via supported debuggers.
7. What is the maximum sample rate of the probes?
The maximum sample rate of an individual probe is 100ksamples/sec. If all 4 probes are connected the maximum sample rate is 50ksamples/sec.
8. How intrusive are the probes?
For the current measurement, shunt resistors are needed. They are included in the probes and optimized for the active range. The probes are designed that the maximum voltage drop is about 100mV over the complete measurement range.
9. How do I connect PowerScale to a target?
Each PowerScale probe must be connected to the supply line of the power domain under test. On existing designs this means cutting the track and soldering in connectors for the PowerScale probe. On new designs a simple header needs to be added in line with each power supply to be monitored.
10. What is the maximum trace depth? Are long time recordings possible?
PowerScale uses a high speed USB connection to the PC. Minimal buffering is required within the PowerScale Unit as all measurement data is streamed to the PC hard disk. This means very long measurement periods are possible, only limited by the size of the PC hard disk. The PowerScale recordings are automatically split into 1GByte files for fast access to the data.