• State Verified Answer
  • Replies 25 replies
  • Subscribers 64 subscribers
  • Views 10299 views
  • Users 0 members are here
Attachments (0)
Nordic Case Info
  • Case ID: 220371
Options
This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

SPI Master pin set and clear

noob_with_ucontrollers

I am trying to run the SPI code on an NRF52382 based custom board. I am using the NRF 52 DK,  Keil uVision 5.0 , SDK 15.2.

I cannot set and clear the SPI relevant pins on my custom board as gpios. The pins I am using are:

SPI_SS_PIN = P0.6
SPI_MISO_PIN = P0.8
SPI_MOSI_PIN = P0.9
SPI_SCK_PIN = P0.7 

and the schematic showing these pins is: 

I was successfully able to toggle all four pins above, (as well as the RESET P0.21) as GPIOs after I did following: 

1. went to sdk_config.h and changed  NRF_LOG_BACKEND_UART_TX_PIN    to pin 5 instead of 6

2. went to OPTIONS FOR TARGET -> C/C++ -> Preprocessor Symbols -> Define and added " CONFIG_NFCT_PINS_AS_GPIOS" after nrf52382.... and removed the line " CONFIG_GPIO_AS_PINRESET"

But as soon as I run the SPI example code in SDK15 I am unable to toggle these pins and use them as gpios. Especially the SPI_SS_PIN which is pin 6, as soon as I run the SPI code this pin fixes to high value and will not clear/go low.  

My thinking is there something wrong with the way the SPI example configures the spi relevant pins? 

https://devzone.nordicsemi.com/f/nordic-q-a/18546/gpio-not-set-or-clear-with-spi-code this guy seemed to have had the same problem running SPI and with the CS pin...

Thank you! 

Parents
  • 0

    Depends perhaps on when you are doing a set/clear test; try setting the SPI_SS_PIN pin to NRF_DRV_SPI_PIN_NOT_USED before initialising the spi, and see if that allows manually set/clear of the /CS pin. Note in this case a manual configuration of the pin to Output must be made as the SPI driver is no longer controlling the pin. The reason for doing this is to ensure nothing else is interfering with the pin; the spi driver does not control the /CS pin with hardware spi but instead runs a set or clear instruction encapsulating the hardware spi transmission. That means the user can just as easily do the set/clear before and after the spi transfer, or allow the handler to do it as in your case.

    Other devices have hardware control over the /CS pin (similar to SCK, MOSI and MISO), but not the nRF52832.

    Also you are probably aware, but if you are testing on a DK then pin 6 is connected in hardware ..

  • 0 in reply to hmolesworth

    Updated:   Now I am configuring the CS pin after I initialize the SPI and it seems to work because the pin goes down to 0.7 V from the earlier Vdd HIGH 3.3V. However, even though the voltage value reduced I do not think this means the SPI_SS_PIN is LOW because the LOW value on my board is typically in millivolts. 

    I am thinking the 0.7V for the CS pin is a floating value. And I do not get why I cannot clear the SPI_SS_PIN?  
    Could this be because the SPI_SS_PIN needs to have a falling edge (and not clear 0) for the SPI peripheral device to be connected? 

    Thanks again

  • 0 in reply to hmolesworth

    I just tried adding the above nrf_gpio_cfg(..) code in my main loop. I add it after "spi_config.ss_pin   = SPI_SS_PIN;" and before I configure SPI_SS_PIN as output. 
    But the pin is still at 0.7 V (not exactly LOW )

  • 0 in reply to noob_with_ucontrollers

    "configure SPI_SS_PIN as output" will revert the pin to default drive strength, which is to low drive; the code I posted replaces that configure, or should be placed after that configure to take effect.

  • 0 in reply to noob_with_ucontrollers

    If I am not using SPI (in the exact same project , I just comment out all the SPI relevant code), I can clear P0.6 (my SPI_SS_PIN) perfectly (it goes down to mVs).... 
    I am not sure what this means? Is it something the SPI code does to the SS pin? 

  • 0 in reply to noob_with_ucontrollers

    When SPI is enabled did you set the pin to NRF_DRV_SPI_PIN_NOT_USED as I mentioned above when manually driving the pin? ie spi_config.ss_pin = NRF_DRV_SPI_PIN_NOT_USED. Otherwise the spi still drives the pin ..

  • 0 in reply to hmolesworth

    Yes I did do that. I set it to NOT_USED in the nrf_drv_spi.h file before I configured it as high low drive. 

    There is another thing I tried after that. I tried enabling my peripheral with pin 6 as a gpio instead of as the SPI slave select pin. I set spi.config.ss_pin to NRF_DRV_SPI_PIN_NOT_USED. And then I did not set Pin 6 to spi.config.ss_pin. Instead I set Pin 6 to LOW as a simple GPIO and said that SPI_SS_PIN is not used (there is no hardware pin connected to SS). 

    But surprisingly I got the same result. 
    The peripheral I am using is the ADS1220 (analog to digital conv). Maybe it sets its slave select to 0.7 V whenever it is provided clock and there is sth withe the ADC?  

Reply
  • 0 in reply to hmolesworth

    Yes I did do that. I set it to NOT_USED in the nrf_drv_spi.h file before I configured it as high low drive. 

    There is another thing I tried after that. I tried enabling my peripheral with pin 6 as a gpio instead of as the SPI slave select pin. I set spi.config.ss_pin to NRF_DRV_SPI_PIN_NOT_USED. And then I did not set Pin 6 to spi.config.ss_pin. Instead I set Pin 6 to LOW as a simple GPIO and said that SPI_SS_PIN is not used (there is no hardware pin connected to SS). 

    But surprisingly I got the same result. 
    The peripheral I am using is the ADS1220 (analog to digital conv). Maybe it sets its slave select to 0.7 V whenever it is provided clock and there is sth withe the ADC?  

Children
Related