nRF5 SDK 17 SPIS example is not capturing all transfers from Master

Question

I am running the subject SPIS example software on a nRF52DK, pca10040, board, as the SPI Slave. The Master is capturing CAN bus messages, 8 bytes per message, and sending them to the slave, along with 2 to 4 additional bytes of information, for output on the serial monitor. The Slave correctly captures and outputs, to the serial monitor, the received transfers from the master for all single frame and first frame messages but only periodically outputs consecutive frame messages. Although the Master makes no use of the messages from the slave, the slave sends out the default "Nordic" message for each completed transfer from the master. A logic analyzer output (snapshot below) shows that all the master messages are being sent to the slave on the MOSI line (second row), but the slave messages on the MISO line (forth row) only appear for the messages that get sent to the serial monitor. The consecutive frames that don't have an associated a slave message do not get sent to the serial monitor. I suspect that this is a problem with the Semaphore Acquire and Release programming, but I can't find the associated code in the example problem. I currently have the master clock rate set as low as it will go at 158 kHz. The attached logic analyzer snapshot shows a first frame message, at the far left, followed by two consecutive frames. The MISO messages are the yellow columns at the bottom. It can be seen that only every eighth consecutive frame has an associated slave message, which are the ones that get sent to the serial monitor. The chip select events are shown at the top and it can be seen that a start and end signal is present for every byte sent by the master. My question is, where can I find the code, in the SPIS example, that detects the start and end events and what parameters should I look at that might be causing this behavior?

Stroker347 · Accepted Answer

I finally realized that the delay between each Slave reception was caused by the time it took to send the logging messages to the UART serial monitor. During this delay, several consecutive frames were being missed. I eliminated all logging to the serial monitor and copied the rx buffer into the tx buffer after each reception. I then received Slave messages for every Master message sent to the Slave. Each Slave message was an echo of the previous Master message and allowed verification that the Master messages were being received. I'll have to create a holding buffer for the incoming Master messages and use that for input to the serial monitor because I don't think the UART baud rates can keep up.

Jared · Answer

Hi Randy, 
 Stroker347 said: difference prevents the messages, from the fatfs portion of the combined project, from displaying and appearing not to work. When I changed it to 0, the fatfs portion displays the SD card info and shows that it is working. 
 The logger module can be used in two different modes: 
 
 Deferred: Which means that the logger will place the log message in a queue and it will be processed and outputted on the serial line, when the NRF_LOG_PROCESS () is called . This is usually done in the main loop in many of our examples. 
 In-place: Which means that the logger will process the log message exactly when NRF_LOG_INFO () is called and will immediately output it on the serial line. This is not preffered if you have real time critical requirements. 
 
 See the documentation on the logger module for more on the different modes, 
 regards 
 Jared

Jared · Answer

Hi, This definition of the sdk_config.h file decides which SPI instance that is used for the APP_SDCARD that is used in the fatfs example: Stroker347 said: If I wanted the fatfs portion to run on SPI2, what would have to be changed? You need to set APP_SDCARD_SPI_INSTANCE to 2 and enable SPI2 by setting: // SPI2_ENABLED - Enable SPI2 instance //========================================================== #ifndef SPI2_ENABLED #define SPI2_ENABLED 1 #endif // SPI2_USE_EASY_DMA - Use EasyDMA #ifndef SPI2_USE_EASY_DMA #define SPI2_USE_EASY_DMA 1 #endif Stroker347 said: And if instead I wanted the SPIS to run on SPI2, what would the changes be? and: NRFX_SPIS_ENABLED 1 SPIS_ENABLED 1 SPIS2_ENABLED 1

Stroker347 · Answer

Jared, before closing this ticket, there is one more thing I need help with. I have my SPI Slave create, and save to the SD card, a binary file containing the messages it receives from the Master. I have written an external program to read that file, format it into a more human legible form, and save it to a text file. I would like to implement this conversion within the Slave. My external program uses the C++ function fprintf_s, with a formatting string, to perform this. It looks like the fatfs files ff.h and ff.c have a function f_printf that might do the same thing. Is there documentation somewhere that describes the functions, and their arguments, that are available within the SDK?

nRF5 SDK 17 SPIS example is not capturing all transfers from Master

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