blend micro SPI

[paul_tanner]

I want to access an SPI-only sensor device from a Blend Micro.

There is a need to avoid collisions between the two uses of the SPI port for the sensor and the nRF chip. I tried testing ble_busy() to see if I could avoid the conflict that way. However, that always comes back with true.

Is there a way to briefly use the SPI port without disabling BLE completely? If not I don't know why the Blend Micro brings out 4 pins for SPI.

This did not get an answer from RedBearLab other than to suggest use of ble_busy(). See redbearlab.zendesk.com/.../68357923-SPI-interference-with-BLE-connection

[Hung Bui]

Hi Paul,

To be honest, I'm not very familiar with the blend micro platform, but what happens if you keep the REQN pin high and then do your task with the SPI sensor?

From my understanding if the REQN is held high, the NRF8001 won't interact with the SPI interface.

Is it possible to control REQN pin on the blendmicro ?

[paul_tanner]

Thx Hung Bui. When using BLE you hand over control of REQN to the BLE subsystem using the ble_set_pins() call. I think that's why you need ble_busy() which should effectively return control when there is nothing to transmit.

[Hung Bui]

OK, so you don't have direct control over the REQN pin and have to use API provided by the system.

From what I can see in the case you quoted, ble_busy() only tell if there is activity with the nRF8001 or not. It doesn't seem that it will hold the REQN line high so you can do other task.

I guess you would need to test with longer connection interval (for example 1 second) and see if ble_busy still return true or not.

Again, I'm not the best to answer Arduino and blendmicro, I would suggest you to request help from RedbearLab.

[paul_tanner]

Thx. I tried sending questions to RedBear but did not get a reply. They have a forum for this sort of thing but my login is not working and the facility to reset that is broken. Their last comment on the subject (see link above) was "ask Nordic".

[David Edwin]

Sharing the SPI between the nRF8001 and other SPI slave devices is possible and many projects have successfully executed on that. However you do need to get control of the lines and not depend on a software that was not written for sharing the SPI lines.

You will need to get control of the SPI driver that is controlling the lines and as Hung stated, keep the REQN line high when controlling the other SPI slave device.

Related Questions: devzone.nordicsemi.com/.../