How to read status pins from 2 L6470 Drivers by single MCU

[Jacek Pieczaba]

Posted on February 07, 2018 at 19:25

Hello,

I am new in this community so please excuse me if the question was already rises. In my application I am planning to use two stepper drivers L6470PD for different stepper motors but driven from the same MCU. Question is the following: Can I share among those two drivers status lines like: FLAG/BUSY/STCK/STBY/SW and by pulling low the CS line define which driver I wanted to use at this moment? Or I should treat the FLAG/BUSY/STCK/STBY/SW lines dedicated for each individual stepper driver.  So in other words plan to use only 5GPIO for two drivers or 10GPIO pins on MCU. 

Thank you very much in advance

Jacek 

#l6470

[Cristiana SCARAMEL]

Posted on February 08, 2018 at 11:17

Hello, the L6470 is compatible with the daisy chain architecture allowing the MCU to drive multiple devices with a single SPI interface (refer to

http://www.st.com/content/ccc/resource/technical/document/application_note/d7/dd/a8/f3/db/3e/49/6f/DM00082126.pdf/files/DM00082126.pdf/jcr:content/translations/en.DM00082126.pdf

for more detailed description).

Concerning to the listed pins, a distinction must be made:

- the STCK, SW and STBY are input lines. If you connect together this pins both devices are driven with the same signal simultaneously.

- the FLAG and BUSY are open-drain output. You can connect them in 'OR' hardware. When the MCU detect a 'LOW' status you can use the SPI to identify the device that pulled low the GPIO.

[Jacek Pieczaba]

Posted on February 08, 2018 at 20:12

Hello,

Thank you very much for quick help. I am going to have two dedicated CS lines from MCU to determine which driver currently I wanted to use. Since I had luck to have some more spare GPIO lines I tide all lines from each drivers separately to each pins on MCU.