When we buy embedded boards, especially hobbyists, it is very rare to see power measurements done on this board. We tried to perform some measurements in the Advertising mode and Connected mode to see if the measurements are inline with the specifications mentioned in the datasheet.
A way to perform Power Measurement on Arduino Nano 33 BLE
To measure the current consumed in different states, we need to find a way to know how much current the board is drawing. For this, there is a option on the board where we can provide 5V input (VUSB) on the breakout header and multi meter can be inserted between the pads SJ1 or SJ5.
We soldered two wires on two pads and connected multi meter.
External voltage of 5V is provided on the VUSB pin of JP2 connector as indicated by the arrow in the below image.
The entire board connectivity is as below.
The default advertising interval is 100ms and the current drawn by Arduino Nano 33 BLE as per datasheet is,
The current drawn by the USB interface is 2.4 mA
Current input to regulator => 4.11-2.4 => 1.71 mA.
Arduino Nano 33 BLE has MP2322 Switching regulator and it's efficiency is considered as ~95% from the below graph.
So, the Arduino Nano module is drawing 2.46 mA on the 3.3V regulator output.
With ~1mA current consumed by module during advertising, the remaining current is 2.46 mA-1 mA = 1.46 mA
The 1.46 mA on 3.3V is the current consumed by,
- GREEN LED glowing - DL2
- DHT11 sensor - Connected externally as shown in first image
- Accelerometer and Magnetometer - U2 and U7
The current consumed by DHT11 sensor is ~1.1 mA
The remaining current drawn by DL2, U2 and U7 is 1.46-1.1 = 0.36 mA
The DL2 LED, HSMG-C190, has the below breakdown voltage,
Considering a typical voltage of 2.2V, the current drawn by LED is 3.3-2.8/300 = 0.12 mA
The remaining current, 0.36 mA-0.12 mA = 0.24 mA is drawn by Accelerometer and Magnetometer (U2 and U7) and any NINA-B306 module internal current
To summarize all the readings in a table in Advertising mode,
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