PI Compute Board:

• RPI-CM4Lite-R1-3: https://www.berrybase.de/raspberry-pi/raspberry-pi-computer/compute-modules/raspberry-pi-compute-module-4-4gb-ram-lite-wlan-43-bt
  • With Heatsink (https://www.pollin.de/p/joy-it-kuehlkoerperset-fuer-raspberry-pi-810822)

Board:

• Wavesahre CM4-IO-BASE-B https://www.waveshare.com/wiki/CM4-IO-BASE-B

WIFI Board:

• R11e-2HPnD https://mikrotik.com/product/R11e-2HPnD

Measurement devices

• USB Power Meter : www.coowootech.com/de/coowoo-usb-digital-power-meter-tester-multimeter-current-and-voltage-monitor-dc-51a-30v-amp-voltage-power-meter-test-speed-of-chargers-cables-capacity-of-power-banks-black.html
• It measures (+-1% Error)
  • Watts
  • WattHours

• PI4 Internal CPU Thermometer
• Multimeter: AM-550-EU PTC Temperature for Wifi Temperature Measurements
  • The temperature of the wifi module by placing the ptc at the heatsink of the wifi module
  • Not highly accurate, but should give a indication

Lab Power source

• Quatpower LN-3003

no bluetooth

• config.txt
• dtoverlay=disable-bt

no wifi

• config.txt
• dtoverlay=disable-wifi

no eth

• https://www.raspberrypi.org/forums/viewtopic.php?t=290965
• dtoverlay=noeth

reduce cpu freq

• config.txt
• arm_freq=500
• arm_freq_min=200
• arm_freq_max=1000

leds

• config.txt
• dtparam=act_led_trigger=none
• dtparam=act_led_activelow=off
• dtparam=pwr_led_trigger=none
• dtparam=pwr_led_activelow=off

no audio

• config.txt
• dtparam=audio=off

no USB

• disabled by default @ CM4 for powersaving
• https://www.jeffgeerling.com/blog/2020/usb-20-ports-not-working-on-compute-module-4-check-your-overlays

Camerasoftware

pi@testi:~$ cat test_dual_cam.py 
import time
from datetime import datetime

import picamera
c0 = picamera.PiCamera(camera_num=0)
c0.resolution = (3280,2464)
c0.exposure_mode = "beach"
c1 = picamera.PiCamera(camera_num=1)
c1.resolution = (3280,2464)
c1.exposure_mode = "beach"

while True:
    pic_stamp = datetime.now()
    filename = pic_stamp.strftime("%Y-%m-%dT%H-%M-%S.%f") + "_a" + ".jpg"
        
    start = time.time()
    c0.capture(filename, format='jpeg', quality=95, thumbnail=None, use_video_port=False)
    end = time.time()
    duration = end-start
    print("[Photo0] image capture took [s]:{0:8.3f}".format(duration))

    filename = pic_stamp.strftime("%Y-%m-%dT%H-%M-%S.%f") + "_b" + ".jpg"
    start = time.time()
    c1.capture(filename, format='jpeg', quality=95, thumbnail=None, use_video_port=False)
    end = time.time()
    duration = end-start
    print("[Photo1] image capture took [s]:{0:8.3f}".format(duration))
    

WifiSoftware

• WIFIBroadcast : https://github.com/booo/wifibroadcast/
• Using 30dbm permanent TX Power @ MCS0

cat /dev/zero  | sudo ./tx wlan0 

Using the power usage in Wh a mean power of ~1.8W is needed when using 2 cameras.

Using the power usage in Wh a mean power of ~3.38W is needed when using 2 cameras + wifibroadcast.

As it turned out that the radio power amplifier was not connected in test #2, i reran the test. Power is provided by the laboratory power source @ 12.3V + DCDC Converter @ 5V for the cm4 board.

NOTE: The sligtly incread Idle power usage is due to the additional DCDC converter, and the powermeasurement BEFORE this converter.