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! 

[hmolesworth]

I have used the ADS1220, albeit on a Dialog BLE radio, and not had any issues; the /CS worst-case leakage on that device is only 10uA and so there must be some other hardware or software item interfering with operation of the pin. Since that only happens with your spi code enabled, either there is something still in contention in the code or maybe there is a fault on the ADS1220; can you try a second board, just in case? Maybe also post the spi init code ..

[noob_with_ucontrollers]

Here is my SPI code : 

I hope the images are visible in a comment...
Thank you for your help! I appreciate it

[hmolesworth]

Ah, I think your code will not work as NULL for tx buffer and length is not valid and will cause an assert. I imagine that setting a command byte but not transmitting it was not what you intended; here is a typical invocation:

mAfePacketTransferComplete = false;
APP_ERROR_CHECK(nrf_drv_spi_transfer(&mAfeSpiInstance, mTxBuf, mRxTxBufLength, mRxBuf, mRxTxBufLength));

Compare this with the nrf_drv_spi_transfer() you are using in your code image, and you will note that the transmit command and length are both NULL, or zero, which is not acceptable.

Also, just as an aside, what pins are the LEDs on?

[hmolesworth]

This is the assert trap:

    ASSERT(p_cb->state != NRF_DRV_STATE_UNINITIALIZED);
    ASSERT(p_xfer_desc->p_tx_buffer != NULL || p_xfer_desc->tx_length == 0);
    ASSERT(p_xfer_desc->p_rx_buffer != NULL || p_xfer_desc->rx_length == 0);

[noob_with_ucontrollers]

hmolesworth So I fixed this ^ that you pointed out. I now initialize m_tx_buf [0] = 0x08 and rest of m_tx_buf array to 0 ; and then do nrf_drv_spi_transfer(&spi, m_tx_buf, tx_length, m_rx_buf, rx_length). But the problem is same as before. I also noticed that there are NO LEDs on my custom PCB device that I am programming so I commented out all the BSP and LED relevant code and run the program again. But that did not fix the issue either. If I use P0.6 as a simple GPIO in the same project with the SPI parts commented out, it works fine and sets to clear if I want to. 

I even redefiened " #define NRF_DRV_SPI_PIN_NOT_USED  0x00   from 0xFF" in the nrf_drv_spi header file to make the default spi_not_used value 0 but that did not work either. 

Another thing that I noticed: Even though I am not initializing, or using the DRDY pin ((P0.10) on my nrf) anywhere in the entire project, just it being connected to the DRDY on the ADS1220 (the ADC) chip on my PCB makes it go to 3.3V (Vdd) instead of a float value (as it should be if it is unused and unconfigured).  Also, when I set the CS pin to HIGH it goes up to 2.6 V (not upto 3.3V like the other pins do when they are HIGH). Do these things say sth about how the ADC is working? 

Thank you once again. 

Since I am working with a custom PCB changing the CS pin would mean making another layout and board. Would you recommend I short pin 6 to pin 5 externally on the nrf52 on the PCB and then use pin 5 to control CS? When you were using ADS1220 , did you get problems with its CS pin at all, and were you externally tying it down to DGND? I remember running SPI on another ADS1220 chip using nrf52 DK first and was getting problems running SPI master successfully earlier as well. This is why I shifted to the custom PCB.