General-purpose MCU power measurement in ST’s debug probe

The unit is called STLINK-V3PWR, and its measurement section is compatible with EEMBC’s ULPMark tests, according to ST.

It provides a programmable 1.6 to 3.6V 500mA (100mV steps, protected at 550mA) source (‘OUT’, see photo) with one-quadrant measurement at 1sample/s to 100ksample/s, with a range of 1.5nA – 550mA  and 160nW – 1.65W.

Behind the current measurements are two inter-wired 12bit 1.6Msample/s ADCs and an auto-ranging algorithm that together provide four ranges: 1.5nA-5μA, 5-380μA, 380μA-15mA and 15-500mA. Resolution ranges from ±2nA to 250μA, which is not linked 1:1 with range switching.

PC-side support comes through the STM32CubeMonitor-Power graphical tool, intended to help visualise the power demand in real-time.

On top of this, the same unit has a separate adjustable 1.6 to 3.6V 2A (2.5A protected) output (‘AUX’, see photo) for powering application hardware.

Partial block diagram of the tester – the SMU is the instrumented power supply

As well as a stand-alone consumption tester and power supply, STLINK-V3PWR can synchronise code execution with the power consumption of an STM32 microcontroller application in real time.

The link to the host PC is via USB Type-C, through which it draws 5V 3A to power itself and provide the two power sources for the target. This same link is used to update probe firmware.

As a debugging and programming probe, JTAG, SWD (serial wire debug) and SWV (serial wire viewer) are provided to communicate with the STM32 MCU on the target hardware. There is also a virtual COM port for UART protocol.

The unit has another set of interfaces through which the host PC, via its USB, can to communicate directly with the target hardware. Called ‘multi-path bridge’, it has its own 22 pin connector and offers SPI, I²C, CAN and GPIO pin interfaces, with an integrated level shifter providing 1.6 <> 3.6V adaptation to the target’s I/O voltage.

Four bi-color LEDs display probe state.

As well as ST’s software tools, the programmer/debugger/power analyser is also supported within Arm’s development tools (Keil MDK enables power profiling, µVision debugger can correlate program events with consumption) and IAR IDE – “Support for STLINK-V3PWR probe within Embedded Workbench for Arm allows developers access to power analysis”, said IAR CTO Anders Holmberg.

The STLINK-V3PWR product page can be found here. The associated data brief is not up to much, but clicking here will cause the detailed and informative user manual to download direct from ST’s website.

For MCU power measurement, see also:
Nordic Semiconductor Power Profiler Kit II
Jetperch Joulescope JS220

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