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CCS/RM48L952: SDHC card command problems

Calvin Wallen IV
Intellectual 270 points
Part Number: RM48L952
Other Parts Discussed in Thread: HALCOGEN

Tool/software: Code Composer Studio

Current setup:

  1. CCSv7
  2. Halcogen v4.07
  3. RM48L952ZWT
  4. SanDisk EDGE 4GB microSD HCI (OEM card) (speed class should be irrelevant since SPI mode treats all SD cards as class 0)
    1. card is formatted with FAT32

I am currently working on a project that will read/write to a microSDHC card using SPI. The CCS project also attempts to enable serial communication in order to set up a user terminal interface. SCI and SPI communications have been validated. The issue I am having deals with the SD card. I have researched the command sequence needed to boot in SPI mode. From what I understand I am supposed to execute the following process:

  1. Set CS pin HIGH (deselects the slave)
  2. Toggle clock at least 74 times (I have done this 80 times by sending dummy byte 0xFF ten times)
  3. Set CS pin LOW (selects the slave)
  4. Send CMD0; arg: 0x0; CRC: 0x95 (response: 0x01)
  5. Send CMD8; arg: 0x000001AA; CRC: 0x87 (response is R7 packet which is R1 followed by an echo of the arg value sent: 0x01; 0x000001AA)
  6. Send CMD55+ACMD41
    1. CMD55; arg: 0x0, CRC: 0x65 (possibly doesn't matter?)
    2. ACMD41; arg: 0x40000000, CRC: 0x77 (possibly doesn't matter?)
      1. arg for ACMD41 sets HCS bit to 1 since I am using high capacity (HC) card
  7. Resend CMD55+ACMD41 n times (waiting for SD card to come out of idle state)

At this point, I have validated all of the commands and their responses leading up to the first iteration of CMD55+ACMD41. I send CMD55 and I get the response 0x01 (R1 as expected); followed by ACMD41 and I get the R1 response of 0x01. This is where the problem occurs. Every subsequent iteration results in a R1 response of 0xFF for both commands (CMD55 + ACMD41). I have been trying to figure out how to fix this and the only information I found talks about the DO pin (data out; represents MISO line) potentially being left in high-Z. Possible remedies would be to put a 47k pull-up resistor on the MISO line, which I can't do because I can't change the hardware I'm using. This leaves me with using an internal pull-up. I see that there is an an internal pull-up option in HALCoGen (PSL) in the Port tab of SPI3, but it is already selected by default. I also read that an internal pull-up on the MISO line should only be used if my uC has 3.3V; and if my uC is 5V, then I shouldn't use an internal pull-up unless my MISO line has a proper 5 -> 3.3V logic translation. Simply put, I am stuck and have not been able to progress with SD card storage/communication. I currently have a github up which has a zip of the CCS project for anyone who wishes to take a closer look at what I have so far. Everything in the CCS project was developed by following a project guide that used the Hercules LaunchPad and HALCoGen. The project guide is split into three parts, which can all navigated from the page I linked (see "Related Blog" table at bottom of linked blog post). The URLs for both resources are included below:

Github URL (has .zip of project):

TI Hercules Launchpad Project Guide:

I have currently logged 43 hours over the last four days on this project and have yet to get this thing working. As usual, any advice/information that could be provided regarding this topic would be greatly appreciated!