Asked
— Edited
Resolved by DJ Sures!
Servo Positions To 270 Degrees
Can I use a servo like this one to get 270 degrees of motion with EZB and ARC?
https://www.amazon.com/ANNIMOS-Digital-Waterproof-DS3218MG-Control/dp/B076CNKQX4
Related Hardware EZ-B v4
The software servo position is arbitrary to any servo, PWM, or serial. Take for instance a dynamixel servo, which will have a range between 0- 4096. There are 4096 positions, not 4096 degrees.
In reference to this 270-degree servo, which is PWM, the servo accepts the same pulse width as the popular 180-degree hobby servos. The difference with a 270-degree servo is that the ARC or Arduino, etc. position value of 180 will be 270 degrees. There is no command for a PWM servo that says "go to XXX degrees". The servo looks at the width of the signal pulse and moves respectively to the amount of rotation it is allowed.
The only difference between the PWM servos that you're used to is the number of rotations on the output shaft is connected to a multiple rotation potentiometer internally.
Here's how a servo works, which is actually quite interesting. It uses PWM pulses to instruct a position. Check this out: https://synthiam.com/Support/Advanced-Fundamentals/servo-motor
The servo has absolutely no idea what a "Degree" is. It only knows what a position is. And a 270-degree servo uses the same input PWM range as a 180-degree servo.
Get one and hook it up to see what I'm explaining - you're a very visual person and seeing it would be helpful to ya.
This servo is : PWM 500-2500us
The pulse width of an EZB microcontroller is handled within the microcontroller.
ARC sends a position, and the microcontroller sends the pulse.
The question would be "What is the pulse width range of an ___________ EZB". Unfortunately, the answer to that question is much larger and would require you to google a bit. Different libraries for different controllers all have different PWM ranges.
Here's a great link about how a servo works. In the link, there are details about the EZ-Robot EZ-B v4 controller and its range, which is the same as some Arduino hardware and other servo controllers: https://synthiam.com/Support/Advanced-Fundamentals/servo-motor
If you're wanting exactly 270 individual steps that each equal 1 degree, then I'd recommend using a servo controller that has an adjustable PWM range. I believe a good one would be the SSC-32: https://synthiam.com/Support/Skills/Servo/SSC-32-Servo-Controller?id=16180
The SSC-32 has an adjustable range from what I recall.
FYI servo city sells a cool little servo travel tuner, that lays inline and is adjustable (within the hard limit)
The change will remember the one that's in the Dynamixel robot skill. Notice how you can specify the number of positions in ARC and the servo skill will scale that.
I have a SSC-32 somewhere in the garage. I've ordered the 270 degree servos, those should be here tomorrow. So def going to be testing in next couple days.