The purpose of the test is to measure the amount of current drawn by the P1L servo. For current measurement background see How to Measure Current with a Multimeter (youtube.com)
Equipment
Multimeter
1 P1L servo
2 breadboards (830 tie points each)
1 BittleX battery
ESP32S microcontroller
BittleX BiBoard, separated (not shown)
ESP32 USB cable
USB BittleX cable
3 male-male black wires
3 male-male red wires
1 male-male green wire
1 pair male - female dupont connector wires (not shown)
Connect the ESP32 ground pin with a black jumper wire to the top power rail ground rat ow 4.
Connect the battery black ground wire to the top power rail ground at row 61,
Connect the battery red power wire to the top power rail positive at row 61,
Add jumper wires to the P1L servo connector, matching the black and red wires, and using the green wire for the signal. This is the same connection used in the Servo Test post.
Connect a red jumper wire from the top power rail at row 50 to row 50, a
Connect the black servo ground wire to the top power rail ground at row 50
Connect the red servo power wire to the top breadboard at row 40, a. (Not the power rail.)
Connect the ESP32 GPIO pin 33 to row 35,a
Connect the servo signal wire to row 35,d
This produces a "open circuit" similar to that of the servo test but with a open connection between the servo power and the positive battery. This is where we will be make the servo current measurement.
Turn the batter on and connect the ESP32 with the USB cable. Verify that the battery light is on and the ESP32 power light is on. The servo should not move.
We make the current measurement by "closing the circuit" between the servo power and the battery power with the multimeter probes. When the circuit is closed, the servo moves. The video demonstrates the measurement.
Link: https://youtu.be/taWsxyK686c
The current fluctuates between 100 and 130 mA. This provides a reference for the servo current when powered.
The final video replaces the ESP32 with the BiBoard to provide the servo signal (but not the servo power.) I made a simple jig to mount the BiBoard on two wooden sticks and used a pair of wires with dupont connectors from the BiBoard ground and signal pins to the ground rail and servo signal at 35, a, replacing the ESP32 signal wire there.
The purpose of this step is not measure current but to verify that the USB only powered BiBoard sends a valid signal to the servo during the bootup sequence. I would not be able to measure the current due to the short time between powering the BiBoard and servo signal end. I would need a more complex circuit to perform that measurement.
Link: https://youtu.be/5V0Bayp_AjI
Results
The servo current ranges between ~(100 - 130) mA. There are 9 servos in the bot so the total current is ~900 - 1170) mA. This does not include the "leak" current for the signal (per servo), the current for the BiBoard itself, or the current to the BiBoard hat. The head servo isn't as active as the others, so it can reduce the overall demand. Even so, that demand is north of 1A