Compiler/AM5718: Multiple devices access over single SPI

Arpita Jena

Part Number: AM5718

Tool/software: TI C/C++ Compiler

Hi,

We have a custom board of AM5718 in which we have 4 MCSPIs. Among those, one MCSPI is connected to 4 ARINC429 chips through 4 different chip selects.

The current observation is : from the RTOS application when we are trying to access any one of the ARINC429 devices by making the corresponding CS as low, other CS are also getting low. As a result, instead of getting data through one CS, we are getting data on all the 4 ARINCs through all 4 different CS.

Can anyone please provide the solution to resolve this ??

CCS version used : 7.04

Thanks

Arpita

over 6 years ago

0 Rahul Prabhu over 6 years ago

TI__Guru** 116830 points

Arpita,

Are you using the driver in single channel mode or multi channel mode. It might be good to share a schematic snapshot of how the MCSPI is connected to the multiple slave devices or provide a block diagram for us to understand the pin set.

Please also refer to other E2E responses around this implemenetation:

https://e2e.ti.com/support/processors/f/791/t/158910?AM335x-SPI-CS-EN

Hope this helps.

Regards,

Rahul

0 Arpita Jena over 6 years ago in reply to Rahul Prabhu

Expert 1055 points

Hi Rahul,

We have tried first with multi channel mode set, but corresponding channel was not going low and all other 3 cs were going low.

After that we tried with single channel mode set, and we observed cs low for all 4 channels even though we were trying to access only one.

We want to drive only one channel at a time and keep all others inactive.

Please find the attached schematic.ct6101-sh01-01_spi.pdf

Regards

Arpita

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Compiler/AM5718: Multiple devices access over single SPI