Hello people
I bought this absolute encoder from ebay and it says it has a pwm output of 1kHz.
Encoder from ebay
I tried to collect some raw samples using labview and NI-6210 sampled at 10kHz, the results in attachment.
Now i'm new at this stuff so I need a second opinion but to me it looks like the pwm freq. is only about 250Hz as opposed to the 1kHz advertised.
Have you a link to the product datasheet ? I don't see one on the EBay page,
Does it really matter if it is only 250Hz ? I presume (without the datasheet) that the mark-space ratio is what matters. The lower frequency would give the Arduino more time to detect it.
...R
Robin2:
Have you a link to the product datasheet ? I don't see one on the EBay page,Does it really matter if it is only 250Hz ? I presume (without the datasheet) that the mark-space ratio is what matters. The lower frequency would give the Arduino more time to detect it.
...R
Thanks for taking an interest.
The 250 Hz does matter since I want to update my controller at 500 Hz. I would not be able to do that if the duty cycle can be 4ms.
This is the model. XYK-BMJ-38Z6-P12
http://www.dhgate.com/product/xyk-bmj-38z6-p12-pwm-signal-out-put-absolute/213269801.html
I'm not an expert on PWM, but I assume the underlying PWM clock is 1kHz. If that's the case, with 12-bits (4096 counts) a PWM value of 1 would be high for 1ms and low for 4095ms.
I've used similar encoders before. You have a choice: do you want 12-bit precision or do you want 1kHz updates? You CANNOT have both with a 16MHz Arduino. You would need a much faster processor and a much more expensive encoder to get both.
500Hz is a good frequency to be updating a motor with current feedback but if you got position feedback at half that rate, that would usually be sufficient.
Well, seems like I could only do updates of less than 250Hz. Do you guys think 100Hz is enough for a inverted pendulum cart?
The link in Reply #2 is not a datasheet. You need to find a datasheet - otherwise you are just wasting your time and money.
...R
