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How to connect remaining lines nFLAG, SYNC and nRST of 4 L6470H connected in Daisy chain configuration

Question asked by Sumeet Patil on Mar 26, 2018

Hello All,

 

I am trying to understand X-Nucleo-IHM02A1 schematic which shows two L6470 connected in a daisy-chain configuration. However, my application needs 4 stepper motors, so I am thinking of using IHM02A1 as starting point for my design which will have 4 L6470PD connected in a daisy-chain configuration.

I noticed in the schematic of IHM02A1, nFLAG/SYNC and nRST of both L6470 are shorted and then connected to MCU pin. Is it fine, to follow same connections for four L6470 connected in a daisy-chain config?

The IHM02A1 user manual says that four such boards can be stacked on top of each other to control 8 stepper motors. I am just not able to completely comprehend one line that says for each respective board, solder bridge SB7, SB8 and SB9 should be shorted. Please advice.

I think I have got the understanding of four IHM02A1 stacked together, please somebody correct me if I am wrong.

Does that mean that each individual board in the stack acts as SPI slave for nucleo while its internal two L6470 ICs connected in daisy chain configuration, and hence each board needs a separate nCS line from the Host Controller? I am assuming the IHM02A1 boards are not connected to each other in daisy chain configuration and are in fact working as SPI slave in which internal SPI buses of L6470 connected in a daisy chain.

So another question is does that mean, simultaneously only two motors can be controlled, and if I want to switch to motor 3 and 4, then i have to change chip select line for that particular board and at same time disconnecting the first board from the host.

http://www.st.com/resource/en/schematic_pack/x-nucleo-ihm02a1_schematic.pdf 

http://www.st.com/content/ccc/resource/technical/document/user_manual/group0/9c/49/e6/da/a3/75/48/b9/DM00237629/files/DM… 

 

Thank you very much for your time and advice in advance.

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