Servolulu: Polulu-compatible servo motor driver

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rklauco
However, unlike TB6612 I am still getting some unwanted "audible" feedback - especially when breaking and stationary. With the same PWM the TB6612 is totally silent. It seems like some sub-harmonic frequency is causing it.
It looks like there is not much documentation/experience discussion on the web about the A4953.
@LoboCNC: Did you already test it with your chip? Did you experience any sound feedback?

With chopper-type drives, it is not uncommon to get audible subharmonics. A lot depends on your exact motor and the components you select for the chopping frequency. In the Servolulu, I'm not actually using the A4953's in chopping mode to control the current. I'm just turning them on or off completely at the servo controller's frequency of 20KHz, and I get no whining.

OK. I am too slow for this
I understand the driving frequency - and based on my ATtiny85 timer set-up, I should operate somewhere within 32kHz. The only other electronics I am using is 2 caps - 470uF and 100nF.
Wiring:
Pin1 - GND
Pin2 - input1
Pin3 - input2
Pin4 - VCC (5V)
Pin5 - VBB (12V)
Pin6 - output to motor 1
Pin7 - GND
Pin8 - output to motor 2
I am not using anything special here - one of the inputs is always low, the other one has PWM with the mentioned frequency and desired pulse width. When I change direction, the other pin gets PWM while the previously active sets to LOW.
Apparently, according the datasheet, I am using fast decay mode (chopping). But I cannot find the reason why - as my current sensing input is connected to ground directly, the mode should be only simple forward/reverse, not fast decay one.
Any chance you can share your schematics? I know the code for the controller is closed source, but the schematics should be fine...

rklauco: looks like you are using the chip in the same mode I am - connecting Vref to +5v effectively eliminates the current control chopping. However, by applying a PWM (active HIGH)- to one input pin while holding the other input low will put the chip in fast decay mode (as you note). I'm using the chip in slow decay mode where I apply an inverted PWM (active LOW) while holding the other input HIGH. Slow decay mode produces a lot less heat and also less abrupt switching which is probably why I've got no noise. Fast decay is really only desirable for high resolution stepper motors where you need to switch the currents very quickly.

Edited 1 time(s). Last edit at 06/14/2016 12:45AM by LoboCNC.

This looks like an ideal product for me. I recently bought a stratasys Dimension (SHDM1000) and I am looking for components to control it. The extruder drives are 12V dc gearmotors with encoders and I am having a some trouble finding drivers for them. EBAY has some leadshine drivers for about $80 that take in Step and Dir inputs but have a min voltage of 18V.

Can anyone give me a link where I can buy a pair of these?

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Tangent1001


Can anyone give me a link where I can buy a pair of these?

Unfortunately, there was not a huge amount of interest in this so I've pretty much dropped the project.

If LoboCNC does not mind, then I can point out to the github repo of misan with his SW - it's easily doable with DC motor driver, any encoder and an arduino (or, in my case, ATtiny85...).