Verifying Board Power Supply and Consumption

Low-power development boards only work if they receive stable power. Before you develop firmware on your board, you should confirm:

  • The board actually receives the correct voltage
  • The board uses a reasonable amount of current

Once you do both, you can be confident that your board power is in a known-good state.

In this guide, you’ll learn how to verify board power supply and consumption on the Texas Instruments CC2340 series and Nordic Semiconductor 54 L series development boards. All you need is a multimeter!

Why Power Verification Matters

Microcontrollers, especially those configured for IoT or other wireless connectivity, spend most of their time in very low-power modes, only using tiny amounts of current. Small power problems, like a weak USB cable, a voltage drop in the regulator, or a poor measurement setup, can significantly skew your readings and even stop your board from working correctly.

For example, the TI CC2340R5 LaunchPad consumes around 0.7 µA during sleep and operates at 3.3 V. A problem with the power supply voltage could cause the onboard microcontroller to reset, fail to flash, or never enter low-power modes.

Verifying the Board Receives Power

The first thing you should do is to confirm that your board is receiving the correct power. Improper power can prevent your board from starting or otherwise cause unpredictable behavior that is impossible to diagnose. Be sure to check the power rail on the board itself, not through the USB cable or other connector.

The following procedure and results are very similar for both the TI CC2340R5 LaunchPad and Nordic nRF54L15.

Procedure

  1. Power the board via USB
  2. Set your multimeter to DC voltage
  3. Place the black probe on GND
  4. Place the red probe on 3V3/VDD
  5. Read the voltage

Results

For both development boards, you should see a voltage of ~3.3 V (see the pictures below). The voltage on your Nordic board may be less than 3.3 V, especially if the power rail was configured differently using Nordic’s Board Configurator tool.

Multimeter reading 3.3V on TI CC2340R5 LaunchPad power rail
Multimeter reading voltage on Nordic nRF54L15 power rail

Measuring Board Current Consumption

Development boards, like the TI CC2340R5 LaunchPad and Nordic nRF54L15, include more than just a microcontroller–they also have LEDs, regulators, and debug circuitry, to name a few. When you measure current on your board, you are measuring the board’s total current consumption, not just that of the microcontroller.

Measuring current is useful during board bring-up because it confirms that your board is powered and running. Later, you can isolate the current from just the microcontroller, but that is not necessary for initial verification.

Important: Multimeter Must Be in Series!

To measure current, you must place the multimeter in series with the power path. Both development boards have a power jumper specifically designed for this purpose.

Procedure

  1. Power off the board
  2. Disconnect the USB
  3. Remove the power jumper from your board
  4. Set your multimeter to DC current (mA)
  5. Connect the multimeter probes to bridge the pins previously connected by the jumper
  6. Power on the board via USB
  7. Read the current

Results

You should see current values similar to the pictures below. Note: These images were taken from boards with no firmware (erased flash), so your results may differ if you already have firmware on your board.

Multimeter showing current consumption on TI CC2340R5 with no firmware
Multimeter showing current consumption on Nordic nRF54L15 with no firmware

Blinking LED Test

Your board’s instantaneous current consumption will change depending on the operations it’s running and the code it’s executing at that very moment. For example, your board will consume more current when powering multiple LEDs and less when in sleep mode.

You can test your board’s consumption with the blinking LED loop from a previous tutorial. When this is running, you should see your board’s current spike and drop every second, in sync with the onboard LED turning on and off.

Multimeter showing current spike during LED blink on TI CC2340R5
Multimeter showing current spike during LED blink on Nordic nRF54L15

Common Issues

Current Too High

Symptoms:

  • LED always on
  • Debug interface active
  • Infinite loop
  • Peripheral enabled
  • Short circuit

Fixes:

  • Stop the firmware
  • Remove any running logic from the firmware (like an LED loop)
  • Measure again

Current Too Low

Symptoms:

  • Microcontroller not running
  • Brownout reset
  • Flash failed
  • Clock not started

Fixes:

  • Measure again
  • Reflash LED loop firmware
  • Watch LED or serial output

Wrapping Up

Confirming that the TI CC2340R5 and Nordic nRF54L15 development boards receive proper power and consume reasonable current with a multimeter is an essential skill. By checking the voltage at the supply rail and measuring current across the board’s power jumper, you can easily verify that your board is powered and running normally.

When you apply this to future firmware development on your board, focus on overall trends rather than exact numbers. Not only are there differences between the TI and Nordic boards (from their hardware designs), but there will also be differences based on the exact firmware you’re running–whether it’s powering I/O, doing tasks periodically, or operating in a different power mode.

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