Difference between nrf_drv_spi_transfer() and nrfx_spim_xfer()?

Question

Hi, 
 
 My goal is to use a timer to trigger SPI transactions and the spi_event_handler() to trigger bluetooth transfers. In order to make it as fast as possible, I would like to run the SPI clk at least 4MHz (if not 8MHz - which I think is possible, right?) and also use easyDMA. Based off this thread: Thread_link . 
 It seems like using the peripheral/spi example should be more than enough to handle all that. If that's the case, what benefit does nrf_spi provide? Is on deprecated? If so... which one? Also is there a difference between SPI0, 1, 2, and 4? 
 
 Thanks so much! 
 Kindest regards, 
 Ryan

Karl Ylvisaker · Accepted Answer

Hello Ryan, 
 ryerye120 said: Thanks again for your help, I really appreciate it! 
 No problem at all, I am happy to help! 
 ryerye120 said: I'm sorry that my original post was a little confusing! 
 No need to apologize, I do my best to understand what you mean and I ask if there is anything I am uncertain about! 
 ryerye120 said: This was my original understanding but I was confused by the main SPI example which conflicts with this understanding. 
 In the sdk_config for the spi example (spi_pca10056) there are the following: 
 Yes, I definitively see how this could be confusing - especially so since the SPI_ENABLED define is targeting the legacy nrf_drv_spi driver, which is the predecessor of the nrfx_spi driver. If you look into the nrf_drv_spi.h file you can see the effects of the SPI0_USE_EASY_DMA define - it switches the driver to use nrfx_spim instead, behind the scenes. The reason for this forwarding is to provide backwards compatibility to older projects when the new nrfx drivers were released, but I concur that it might seem strange when starting to work with the nrfx drivers directly. As an additional note, I would recommend that you remove all legacy peripheral defines from your sdk_config (such as SPI_ENABLED, SAADC_ENABLED, etc) and instead only have your nrfx driver defines present (such as NRFX_SPIM_ENABLED, NRFX_SAADC_ENABLED, etc). This is recommended due to the apply_old_config.h file - which was added for backwards compatibility - which will overwrite your NRFX defines if the legacy *_ENABLED is left defined in the sdk_config. 
 ryerye120 said: To summarize, SPI0 is enabled and set to use easyDMA, but no specific NRFX_SPIMs are enabled. What does "SPI0_USE_EASY_DMA" do if it's just for SPI (and not SPIM)? Is the "SPI0_USE_EASY_DMA" config bit just ignored? 
 As mentioned, it makes the switch to the SPIM driver instead, since the SPIM driver is implemented with easyDMA. 
 ryerye120 said: Also, thank you for the heads up on the SPIM3 errata! Is there a particular reason to use SPIM3 instead of SPIM0,1, or 2? 
 The SPIM3 is the high speed instance, so if you need speeds over 8 MHz you will need to use SPIM3 like detailed in the SPI instance register's I referenced in my previous comment. Please do not hesitate to ask if any part of this still should be unclear! The backwards compatibility files and behavior is known for having caused some confusion in the past. Best regards, Karl

Difference between nrf_drv_spi_transfer() and nrfx_spim_xfer()?

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