Disabling/enabling SPI Pins for SD Card

RE: Disabling/enabling SPI Pins for SD Card

Jørgen Holmefjord — Mon, 06 Aug 2018 18:01:50 GMT

This is not related to this question, unless you cut VCC to the SD Card. Please post a new question where you described your issue and setup in details.

RE: Disabling/enabling SPI Pins for SD Card

Renato Silva — Mon, 06 Aug 2018 17:20:41 GMT

Did you resolve this problem?

I have a problem in fatfs example (SDK14)

The serial show me the follow error.

<info> app: FATFS example.
<info> app: Initializing disk 0 (SDC)...
<info> app: Capacity: 59400 MB
<info> app: Mounting volume...
<info> app: Mount failed.

RE: Disabling/enabling SPI Pins for SD Card

Jørgen Holmefjord — Mon, 30 Oct 2017 08:51:46 GMT

You can only drive pins configured as output low. You can configure the pull-settings of the MISO line using the sdk_config macro NRF_SPI_DRV_MISO_PULLUP_CFG (in SDK 14.1.0).

RE: Disabling/enabling SPI Pins for SD Card

Cornel Brülisauer — Fri, 27 Oct 2017 13:45:03 GMT

Ok, thank you for your help. Maybe I can save some power somewhere else. One last try may be to force all SPI data lines low. Is this possible?

RE: Disabling/enabling SPI Pins for SD Card

Jørgen Holmefjord — Fri, 27 Oct 2017 13:07:40 GMT

This is what I could find in chapter 7 of the SD card Physical Layer simplified specifications:

The SD card is powered up in the SD mode. It will enter SPI mode if the CS signal is asserted (negative) during the reception of the reset command(CMD0).

I suspect this will cause the issue you are seing, if you do not perform the initialization sequence after power on.

RE: Disabling/enabling SPI Pins for SD Card

Cornel Brülisauer — Fri, 27 Oct 2017 10:30:40 GMT

No, unfortunately I don't know. This was my question in the beginning and I hoped sombody may no about this.

RE: Disabling/enabling SPI Pins for SD Card

Jørgen Holmefjord — Fri, 27 Oct 2017 08:43:35 GMT

Do you know if the SD card can work after VCC have been cut, without reinitialization?

RE: Disabling/enabling SPI Pins for SD Card

Cornel Brülisauer — Fri, 27 Oct 2017 07:37:01 GMT

That is a mistake. I looked in the datasheet and accidentally looked up the register configuration for the SPIM module, not the SPI module. I thought, that the connect bit needs to be set, thats why I added |0x80000000. It is now not stuck anymore in the default_wait_function(void), but it fails to mount the card. The f_mount function returns FR_DISK_ERR. The SPI works after reconnecting, I tested it with a logic analyzer. But the MISO signal stays high constantly.

RE: Disabling/enabling SPI Pins for SD Card

Jørgen Holmefjord — Thu, 26 Oct 2017 14:46:44 GMT

What is the | 0x80000000 for?

RE: Disabling/enabling SPI Pins for SD Card

Cornel Brülisauer — Thu, 26 Oct 2017 14:29:14 GMT

It is also a mystery to me, why there is still a voltage at the vcc line. But still, I want to disconnect the pins, in order to save power anyhow. But maybe I have to look into my mosfet switch again... I am using the SPI peripheral (SDK 12.3). The disconnect works fine. But now I have problems with enabling it again. I enable the pins like this:

 NRF_SPI1->PSEL.SCK = SDC_SCK_PIN | 0x80000000;
	NRF_SPI1->PSEL.MISO = SDC_MISO_PIN | 0x80000000;
	NRF_SPI1->PSEL.MOSI = SDC_MOSI_PIN | 0x80000000;

Is that correct? If I then use the function:

   if (f_mount(&Fatfs,"/",1) != FR_OK)
  {
		NRF_LOG_INFO("Mount failed.\r\n");
		return;
  }

It gets stuck in the default_wait_func(void) function in the file diskio_blkdev.c and stays there forever. Am I doing something wrong when reconnecting the pin or do I need to initialize the card again (as shown in the first question)?

RE: Disabling/enabling SPI Pins for SD Card

Jørgen Holmefjord — Thu, 26 Oct 2017 12:21:01 GMT

I don't understand how the SPI data lines can power your SD card if you have disconnected VCC. You can try disconnecting the pins of the SPI peripheral by setting the PSEL registers to disable:

NRF_SPIMx->PSEL.SCK = (SPIM_PSEL_SCK_CONNECT_Disconnected<< SPIM_PSEL_SCK_CONNECT_Pos)
NRF_SPIMx->PSEL.MOSI = (SPIM_PSEL_MOSI_CONNECT_Disconnected << SPIM_PSEL_MOSI_CONNECT_Pos)
NRF_SPIMx->PSEL.MISO = (SPIM_PSEL_MISO_CONNECT_Disconnected << SPIM_PSEL_MISO_CONNECT_Pos)

If you are using SPIM peripheral (with EasyDMA support), where x is the SPIM instance used.

Note that you need to connect the pins again before the SPI can do any transfers again.