SIMPLELINK-CC2640R2-SDK: CC2640R2 SDSPI and different CS line

D B

Part Number: SIMPLELINK-CC2640R2-SDK
Other Parts Discussed in Thread: LAUNCHXL-CC2640R2, TXB0104

Hi,

We are attempting to use SDSPI with a CC2640R2 chip but with a different default SPI CS line (IOID_21):

#define CC2640R2_LAUNCHXL_SPI0_MISO             IOID_8          /* RF1.20 */
#define CC2640R2_LAUNCHXL_SPI0_MOSI             IOID_9          /* RF1.18 */
#define CC2640R2_LAUNCHXL_SPI0_CLK              IOID_10         /* RF1.16 */
#define CC2640R2_LAUNCHXL_SPI0_CSN              IOID_21

The SDK we're using is `SimpleLink CC2640R2 SDK (4.40.00.10)` through the CCS Cloud.

We use the default `sdraw.c` example in the CCS Cloud, but add the header line:

`#include <ti/drivers/sd/SDSPI.h>`

The code fails on the `SD_initialize` command and I think I know why: after probing the SPI lines with an oscilloscope, it looks like the 6 byte command packet and the 1 byte reponse are on the the *same* MOSI line. The 1 byte response should be on the MISO line, but no data ever appears on this line.

I think this means that the SD driver is still in SD mode and not going into SPI mode.

How can I make it use SPI mode instead?

Thanks!

over 4 years ago

0 Ryan Brown1 over 4 years ago

TI__Guru**** 216527 points

Hi D B,

Did you create SDSPI_Handle/SDSPIParams, replace SD_init with SDSPI_Params_init, and use SDSPI_open instead of SD_open? I recommend you review some relevant E2E threads and the TI Drivers Runtime APIs.

Regards,
Ryan

0 D B over 4 years ago in reply to Ryan Brown1

Prodigy 70 points

Hi,

No I did not use them because none of those API methods exist in SDK 4.40. It looks like all the SDSPI code is hooked up automagically now and the SDSPI.h header is minimal.

I've read all the forum posts I could on using SDSPI but they all reference older SDKs.

0 Ryan Brown1 over 4 years ago in reply to D B

TI__Guru**** 216527 points

My apologies for the confusion, after further reviewing the sdraw example I can surmise that it is indeed already using the SPI peripheral to communicate and GPIOCC26XX_DIO_21/CC2640R2_LAUNCHXL_SDSPI_CS as the chip select. You can observe this from the CC2640R2_LAUNCHXL.c/h files and do not need to modify CC2640R2_LAUNCHXL_SPI0_CSN or add #include <ti/drivers/sd/SDSPI.h>. Are you using a LAUNCHXL-CC2640R2 and compatible SD card BoosterPack to evaluate this example?

Regards,
Ryan

0 D B over 4 years ago in reply to Ryan Brown1

Prodigy 70 points

Yes, we are using a LAUNCHXL-CC2640R2 with a custom board with the CC2640R2 on it; it is hooked to a microSD socket via a voltage translator, TXB0104.

The SPI protocol I reference is from this handy page:

http://www.chlazza.net/sdcardinfo.html

The CMD response is on MOSI, but I think is supposed to be on MISO

0 Ryan Brown1 over 4 years ago in reply to D B

TI__Guru**** 216527 points

This could be a hardware issue, you should use a logic analyzer or oscilloscope to further monitor the SPI lines.

Regards,
Ryan

0 D B over 4 years ago in reply to Ryan Brown1

Prodigy 70 points

I have verified all lines are properly connected and data is going to the SD card (probed via oscilloscope). But I see the response packet on the wrong line which suggests the chip is operating in 'SD' mode instead of 'SPI' mode (see opening post).

I want to know if I'm missing something with the code. So far it doesn't look like anything I can find is wrong, and that is why I'm posting here.

0 Ryan Brown1 over 4 years ago in reply to D B

TI__Guru**** 216527 points

"The SD Card powers up in SD mode. To switch the card to SPI mode, the CS signal must be asserted while the host issues a reset command to the card. Once a particular protocol is configured, it cannot be changed while power is applied. The only way to switch between protocol modes is to do a power cycle."

Have you monitored the CS pin during a reset? This issue seems more related to SD card initialization.

Regards,
Ryan

0 D B over 4 years ago in reply to Ryan Brown1

Prodigy 70 points

Yes, CS, MOSI, and CLK seem to be behaving properly.

There is a series of 10 bytes (all ones) that is sent on the MOSI line while the CS signal is asserted (active-low), then the CMD0 packet is sent several times in a row to try and reset the device.

Where are you reading that documentation?

0 Ryan Brown1 over 4 years ago in reply to D B

TI__Guru**** 216527 points

https://www.cactus-tech.com/wp-content/uploads/2019/03/An-Introduction-To-SD-Card-Interface.pdf but it's other places online as well.

Arm-based microcontrollers

Arm-based microcontrollers forum

SIMPLELINK-CC2640R2-SDK: CC2640R2 SDSPI and different CS line