reverse sub micro servo reverse micro servo: practical guide to selection and wiring

01What is a reverse micro servo (reverse sub microservo）？

Reverse micro servo is a kind of micro servo motor that supports forward and reverse rotation control. Its size is usually less than 20 mm by 10 mm by 15 mm. The working voltage is mostly 3 volts to 6 volts. Unlike ordinary servo, which can only rotate in one direction,reverse sub microservoIt can achieve clockwise and counterclockwise rotation with the help of signal pulses. It is often used in scenes that have strict requirements on space and reversal control, such as small robotic arms, model car steering, and automatic door locks.

Based on the actual measurement experience of the YPMFG product line, here is a complete set of operation methods from model selection to debugging, ensuring that you can control all key points of the device at one time.

02Three core selection factors (meets 90% of common needs)

The key point of professional selection is to selectreverse sub microservoBefore that, you must first clarify three parameters, namely stall torque, rotation angle range, and signal logic.

1. In terms of output torque, the more common micro servo torque range is between 0.5kg·cm and 2.0kg·cm. For driving plastic small arms, you should choose a torque below 0.8kg·cm, while for driving metal connecting rods or light-load door locks, you need to choose a torque above 1.5kg·cm. There is such a case, a DIY small grabber uses a reverse servo with a torque of 1.2kg·cm, and it frequently gets stuck when grabbing a 50g object. After that, it was replaced with a 1.8kg·cm model before it returned to normal status.

2. In terms of rotation angle, the angles supported by the standard reverse servo include ±45°, ±90° or continuous rotation. The continuous rotation type, that is, the 360° type, does not have angle feedback and is only used when driving wheels and other rotations. The type with angle feedback, such as ±90°, is used for precise positioning. It should be selected according to your control goals. If it is for positioning, choose the feedback type, and if it is for rotation, choose the continuous type.

3. Signal interface, mostreverse sub micro servoUse PWM (Pulse Width Modulation) for control. The standard neutral pulse width is 1500μs, the reverse pulse width is less than 1300μs, and the forward pulse width is higher than 1700μs. Be sure to check whether the output PWM frequency of your controller (Arduino, STM32, etc.) matches (usually 50Hz~400Hz).

03Wiring and reverse control settings (completed in three steps)

The debugging skills and methods in actual combat, the following steps have been verified in hundreds of actual projects, and operating in sequence can avoid 99% of burnout or out-of-control failures.

Step 1: Power Connection

Connect the red wire to VCC (3V to 6V) and the black or brown wire to GND. A common mistake is: There is no problem if you connect a 6V servo to a 5V system, but if you connect a 3V servo to 6V, it will be burned immediately. If the power supply voltage is not clear, use an adjustable regulated power supply starting from 3V and gradually adjust it upwards to see if the servo is heating up.

Step 2: Signal cable connection

The orange or yellow wire is connected to the PWM output pin of the controller. Reverse servo does not distinguish between forward and reverse signal lines. The logic of reversal is completely determined by the pulse width.There is a case where a user mistakenly connected the signal line to the digital output pin, causing the servo to not rotate.; After the PWM pin is correctly connected, it will return to the normal state.

Step 3: Program the reversal

Send such a set of pulse sequences, in which the pulse width range corresponding to the reverse command is 1000μs to 1300μs. Among them, the common one is 1000μs as the maximum reverse speed, and the pulse width range corresponding to the forward command is 1700μs to 2000μs.

Sample code logic (pseudocode):

Here's what it looks like rephrased: Write it as a number of microseconds (1000), turning as fast as possible in the exact opposite direction.

writeMicroseconds(1500);→ Stop

Writing two thousand in units of millionths of a second translates into, forward continuous rotation toward full speed.

If the reverse direction of your reverse sub-microserver is opposite to the expected direction, then swap the high pulse width value and the low pulse width value of the pulse width modulation.。

04Frequently Asked Questions (Q/A)

Q1：reverse sub micro servoWhat should I do if it doesn’t spin after being plugged in, but I can hear a buzzing sound?

A: Cut off the power supply immediately. The buzzing sound means that the rotor is blocked. To check whether the load is stuck or the torque is insufficient, perform a no-load test first. If the no-load condition is normal, upgrade to a model with greater torque.

Q2: After sending a reversal pulse, the servo only shakes but does not rotate. What is the reason?

A: There is a mismatch in the PWM frequency. Set the frequency to 50Hz, which means the period is 20ms, and the pulse width should be in the range of 1000 to 2000μs. If jitter still occurs, check whether the power supply current is less than 500mA.

Q3: Can the continuous rotation reverse servo be changed back to angle control?

A: No.The continuous rotation type removes the angle feedback potentiometer, and the hardware is already fixed.. If you need angle control, you must buy a standard reverse servo with feedback.

Q4: Multiplereverse sub micro servoWill sharing a power supply interfere with each other?

A: Yes, at the moment when each servo starts, its current can reach 1A. It is recommended that each servo be powered separately, or use a voltage stabilizing module with a total current greater than or equal to 3A, and connect a 100μF capacitor in parallel to each servo power pin.

Q5: Can the reverse speed of the reverse servo be accurately adjusted?

A: Yes, the further the pulse width deviates from 1500μs, the faster the speed. For example, the reversal speed of 1200μs is faster than that of 1300μs. The linear relationship is: if the pulse width changes by 10μs, the speed change is approximately 2% of the rated value.

05Action recommendations and core conclusions

The core value of the reverse ultra-micro servo is that it can achieve two-way controllable rotation. Selecting the appropriate torque, angle range and PWM signal logic are the three key pillars to achieve success. Any neglect of power supply matching or improper attempts at signal frequency will result in jitter, failure to rotate, or burnout.

Immediate action list:

1. Measure the mass of your load, the unit is g, measure the length of the rotating arm, the unit is cm, calculate the required torque, the calculation method is kg·cm = mass × moment arm/100.

2. Confirm the controller PWM output capability (voltage, frequency, resolution).

3. Before purchasing, ask for the data sheet from the seller, and focus on checking the "reverse pulse width range" and "no-load current".

4. When powering on for the first time, be sure to use a power supply with a current limit of 500mA for testing.

Follow the guidelines mentioned above and you can complete your first one in less than 30 minutesreverse sub micro servoFor reverse control, if you encounter an abnormal situation not covered in this article, first check whether the ground loop and signal line contact are reliable.