DRV8711EVM controlling

varun lal

Prodigy 80 points

Other Parts Discussed in Thread: DRV8711EVM, DRV8818, DRV8825, DRV8711

can we control DRV8711EVM using just a step and direction pulse from a microcontroller ? or we need SPI to control ?

over 11 years ago

0 Ryan Kehr over 11 years ago

TI__Guru 55565 points

Varun,

You will need SPI control to configure the registers. The default register map may work for your application, but a write to the first bit in the CNTL register is required to enable the outputs. Default is disabled.

0 varun lal over 11 years ago in reply to Ryan Kehr

Prodigy 80 points

Ok, I was looking for a parallel interface like tb6600 from toshiba(but no hbridge), to be able to control directly from parallel port, is there any IC like that from TI ?

0 Ryan Kehr over 11 years ago in reply to varun lal

TI__Guru 55565 points

If you don't need over 2.5 amps, our drv8818 or drv8825 have a similar interface.

0 John Harris over 11 years ago in reply to Ryan Kehr

Prodigy 80 points

I have microcontroller to DRV8711 SPI interface working, but I find I can only read the register contents when in 'Sleep' mode. When not in 'Sleep' I can write the registers OK, for example enabling and disabling the IC, but at no time is there any output from pin 17 SDATO. I do have an external pullup resistor 10K to 3.3V.

Is this normal, or am I missing something in the configuration process?

0 Wilson Zuo over 11 years ago in reply to John Harris

TI__Mastermind 26065 points

Hi John

In our EVM, we can always see the SDATO when you start a read SPI cycle no matter in or not in SLEEP and the motor running or not. But when motor is enabled, it is possible that the current noise will affect the SPI communication.

Could you test the real waveform on SDATO pin (Pulled up) when you start a READ sequence instead out reading the back value from MCU of GUI display?

Thanks,

Wilson Zuo

Motor Application Team

0 John Harris over 11 years ago in reply to Wilson Zuo

Prodigy 80 points

Hi Wilson, I have a two channel scope. I trigger from one channel connected to SCS, and connect the other channel to SDATO, then read each register in turn. When in 'Sleep' mode I see the waveform on the SDATO line corresponding to the bits written into each register, but when not in 'Sleep' SDATO stays high though the time that theSCS input is high.

The length of the SCS waveform is the same in both 'Sleep' and not 'Sleep', also if I switch from monitoring SDATO to monitor SCLK I see the same string of clock pulses in both cases.

John

0 Wilson Zuo over 11 years ago in reply to John Harris

TI__Mastermind 26065 points

Hi John

That is strange. Acturally I did a bench check on your question, I can see the SDATO quite normal in SLEEP mode or normal mode. Did you test on TI EVM or your own board? if possible, I suggest you can swap another DRV8711 to test again. Also check you software on the READ and WRITE bit of your SPI cycle.

Thanks.

Wilson

0 John Harris over 11 years ago in reply to Wilson Zuo

Prodigy 80 points

Hi Wilson,

It is not a TI EVM board. I have been assigned the task of replacing an Allegro A3986SLD in an existing design with the TI DRV8711. This seemed fairly simple, as I had designed the existing board. I followed the data sheet carefully, but I may have missed something. Is the schematic of the TI EVM board available? If so I would like to check my schematic against it.

John

0 Nicholas Oborny over 11 years ago in reply to John Harris

TI__Mastermind 21305 points

Hi John,

http://www.ti.com/tool/drv8711evm

Near the bottom of this page is a zip folder with all of the design files. Let us know if you have any questions.

0 John Harris over 11 years ago in reply to Nicholas Oborny

Prodigy 80 points

Problem solved. My start sequence is. Assert Driver RESET, unassert Driver RESET, assert SLEEP, configure registers, unassert SLEEP, enable Driver.

Problem was in my code the line to unassert RESET was commented out. I think part of early software testing. When I uncommitted the line, everything worked.

Thanks for your help.

John