Multiple Instances of SPI doesn't seem to be working.

[Rajat]

Hi Everyone

I am trying to use 2 instances of SPI SPI0 AND SPI2 for Epaper Display and MCP2515 CAN bus module respectively. 

Epaper and CAN are working fine if one of them is run. However if i run both of them , only one of the Peripherals work either CAN or the EPAPER.

What can be the possible reason for this behaviour.

I am suing SDK 15.0 with S140 Softdevice on Segger Embedded Studio on NRF52840.

Thanks 

Rajat!

[Kenneth]

Hi,

Have you checked that the SPI instances (0 and 2) you are using are not overlapping with other peripherals you may have enabled:
http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/memory.html?cp=2_0_0_3_1_3#topic 

Are you able to replicate this by simply extending the SDK example to use instance 0 and 2?
Try \nRF5_SDK_15.2.0_9412b96\nRF5_SDK_15.2.0_9412b96\examples\peripheral\spi\

E.g. in main.c add:
static const nrf_drv_spi_t spi2 = NRF_DRV_SPI_INSTANCE(2); /**< SPI instance 2. */ // #define SPI2_ENABLED 1 in sdk_config.h

Best regards,
Kenneth

[Rajat]

No, They are not overlapping with other peripherals.

This is what is happening now.

If i remove the Epaper from the hardware and test, it works fine.

But when i connect the epaper , CAN module doesn't get initalised.

[Kenneth]

Rajat said:

But when i connect the epaper , CAN module doesn't get initalised.

If you look at a logic analyzer plot between the two you can see what difference?

Maybe if you do a dump of the SPI configuration registers with and without the epaper you can identify the difference?

[Rajat]

 So far we are not using the Epaper, But still i would like to let you know that 

The problem was whenever i remove the Epaper, then CAN Works 

But whenever i connect the epaper , CAN initalization gets failed. 

I saw on logic analyzer which showed me that Epaper was causing the BUSY(MISO) pin to be low and hence instead of data that was supposed to be on MISO Lines , it became 0 .

So CAN  Initilazation failed.

Do You have any workaround for this in your mind?

Thanks!

[Kenneth]

How about using a 1kohm serie resistor in series with the MISO pin?

Best regards,
Kenneth