Peter Scheunert

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8 years, 3 months ago.

Does the target run stand alone after programming?

I want to remove the ST-LINK/V2-1 debug part of the pcb to reduce the power consumption

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Last updated: 20 Apr 2021
Affordable and flexible platform to ease prototyping using a STM32L152RET6 microcontroller.

Check the clock set up code, I believe by default its set to external clock, from the 8Mhz interface CPU clock. This needs to be changed to start on HSE.

posted by Paul Staron 23 Feb 2017

1 Answer

Paul Staron
8 years, 3 months ago.

Yes, you can break off the ST-Link part and use the MCU board on its own. The MCU power level is around 9mA at highest clock speed.

A couple of considerations.

Some Nucleo's use the interface 8MHz clock source to clock the MCU, SB16 (MCO) link will be closed if this is the case. If the link is open the MCU generates its own IRC clock source. Fitting the crystals is desirable for accurate clocking in any case. Clock source set up was detecting this, not sure if its still working.

The MCU can be powered by the 3.3v regulator U3, position the PWR jumper to E5V and supply power to the E5V and GND Morpho pins. This regulator may not be very low IQ, 1 or 2 mA, I have not checked.

To program the MCU again, use the CN4 SWD connectors to the Morpho MCU SWD connections, see the circuit diagram that shows which MCU pins need connecting.

Unless its been fixed, the MCU will not currently wake up from deepsleep, if it did work the deepsleep power will be 1 or 2 uA.

I'm using the Nucleo-L476RG with the 8MHz crystal fitted. This is by far the most bug free low power Nucleo. 80MHz clock speed runs at 15mA with deepsleep coming in at 8uA. Fast chip!

Accepted Answer

Thank you for the detailed answer. According to the data sheet, the LDO has a quiescent current of 20-100µA depending on load current. I think, the status LED consumes more power ;-)

posted by Peter Scheunert 07 Jan 2016

Paul, ¿why there is no deepsleep() available in broken-off boards? ¿Is there a way around it? I have a custom board with both clocks, and the MCU cannot awake form deepsleep(), only sleep().

posted by Guillermo García 23 Feb 2017