Interfacing VNH3SP30

kimh

I am trying to interface a Motor Driver chip, the VNH3SP30, does any one know how to get the 5V logic inputs for INA, INB and PWM etc to work with 3.3V on propeller.
The issue is the docs for the chip suggest a minimum logic high level of 3.25 volts and not the usual TTL 1.4V or CMOS 2.5V logic This seems touch and go for the 3.3V high output of the propeller.

Will a direct connection to the propellar work in this case ?
If not what is a good way to interafce this ?
The copious documents on the 3.3V to 5V Interfacing Issue on the forums and elsewhere ignore the issue when higher than CMOS High voltages are required.

I note there is no circuit for the Parralax HB-25 driver product that uses this chip, is that available ?
Seems there is also no documentation for this product ?

hover1

There was talk of something similar here:

·http://forums.parallax.com/showthread.php?p=805489
The new Stingray robot uses bi-directional level translators:
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/stingray/List/0/SortField/4/ProductID/601/Default.aspx

And the new Propeller based servo controller uses a TX0108 auto direction translator:
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/PSC/List/0/SortField/4/ProductID/595/Default.aspx


Jim

Post Edited (hover1) : 10/22/2009 11:40:18 AM GMT

Pavel

I use MAX3001 (8 lines) and MAX3378 (4 lines) bidirectional level shifters for most cases where bidirectional translation between 3.3V and 5V is needed. Other chips that work same way are TXB0104 (4 lines), TXS0102 (2 lines) and TXS0108 (8 lines). I think TXB0104 is available in SOIC, everything else is 0.65mm pitch, so some soldering skills are needed. On the breadboard I use adapter boards from SparkFun to mount the chips (you solder chips on little DIP boards).

Timmoore

I had the same problem with a MC33887 motor controller. I ended up using a 1K inline resistor and a 3.3K pullup to 5V.

············ ············· +5V
······················ 3k3···· 1K
········ MC33887────┴──── prop pin

Post Edited (Timmoore) : 10/22/2009 4:41:28 PM GMT

SailerMan

I have been using this chip a little... I created a board that has two of these chips controlled with an SX48 (Jon Williams helped me with some ASM code for the serial connection) ... I just send commands to it serially.. It was something that was fun to build. I'll see if I can drive the chip properly with a Propeller. I don't have a breakout board for this chip so I'm not sure how to test it.. Pololu.com has these chips mounted to a PCB.