SparkFun will be closed Nov 26th and 27th for the Thanksgiving holiday. Orders placed after 2:00pm MT on the 25th will ship out Monday the 30th.


Member Since: January 10, 2012

Country: United States

  • good, evenhanded post, Mike,

    The ease of use is what is killing it. Just like laser pointers, as mentioned by another poster. Time was, that you had to actually know something to use a laser. High voltage power supply, etc. Now any boob can buy a pointer and lase airplanes.

    Time was that you needed to have some skill to operate a RC plane. it required persistence, and money, and skill. Now any idiot can buy a quad, and with very little skill at all, and almost zero experience, fly one and do all manner of dumb stuff.

    and computers…..oooops, rant alert, rant alert breep breep

  • Sure. I changed a couple of things since I wrote the above post…..

    I set it up for a hold current of 1A and a run current of 1A at a speed of 400 step/s (this is from my notes)

    This required a motor voltage of 20 volts. The ST software really doesn’t like it if you try less voltage with the above specs.

    kval_hold=13 ; kval_acc=1b ; kval_run=1b ; st_slip= 78 ; int_speed= 1908 ; fn_slp_acc= 8a ; fn_slp_dec= 8a

    all values are in hexadecimal. Your Mileage May Vary.

    Good Luck!

    The motor runs really nicely, with LOTS of power.

    Added later: I should note that I added a 5 ohm 10 watt resistor in series with each of the two motor power leads to limit the current. The center tap is just ignored. These do get a tad warm in continuous operation.

  • Well, I just got the thing working. Like others have said, each and every command has to have the CS cycled. If it is a multiple byte command, you need a cs cycle for each byte. If you want to get data back, you need to send a 00 (nop) to it after you send the data request command, wait for the sent flag in the SPI to raise, wait a bit, then read the spi data register. And cycle the cs for each read.

    Also, make sure you have the Standby/reset high.

    Oh, yeah….you do need to have main motor power (VS) to the board. It is not enough to supply 5V to the 5V terminal. If you don’t have motor power to the board, all you’ll read is zeros….(ask me how I know this).

    Also, like was said earlier, you should setup the param registers. Get the software from the ST website to get the proper values. Your motor will run smoother and better.

    I am currently driving a ROB-10847, with about 15 volts to the VS, and the board doesn’t even get warm….‘course that is unloaded.

    Its a really nice board/chip. Smooth and easy. Once you can talk to it.

  • Well, I have a comment, also.

    I sympathize with your call. It seems like you made the best call you could given the information you had. And I laud your apparently libertarian leanings.

    BUT….and this is a biggie….

    What if you get subpoenaed to give out a list of all the folk who you have sent an IMU to? By, say, Homeland Security? IMU’s are pretty potentially dangerous things, ‘specially coupled with GPS.

    This is a rhetorical question, but it deserves a bit of cogitation.

  • Now THATS terribly cool……I can think of a few somewhat more nefarious things to do with this…..and a great illustration of using a few shield boards together…..

No public wish lists :(