topic eMMC always setting busy bit in cmd1 response in LPC Microcontrollers

eMMC always setting busy bit in cmd1 response

iann — Thu, 01 Oct 2020 10:15:42 GMT

Hi we're using a LPC54608 with an external sandisk (sdinbda6-64g) eMMC memory device which is failing to complete the initialisation phase. (using sdk 2.7.0)

Having looked at the clk, cmd and d0 lines on the scope I can see the processor is sending cmd0 to put it into idle state then is in a constant loop sending cmd1 with the reply always showing bit 31 of OCR as busy (0).

The eMMC part is connected to 3V3 for VCC and VCCQ at 1V8 with power rails measured at 3.32 and 1.81

Is there anything on the nxp processor side that can stop the init phase? Or any extra debug that can be turned on?

Kind regards

Ian

Re: eMMC always setting busy bit in cmd1 response

Alexis_A — Tue, 06 Oct 2020 00:19:28 GMT

Hello @iann ,

Are you using a custom board or a development board? If you're using a custom, could you try replicating this in one of our development boards?

Are you using an SDK example to test this?

Also, the latest SDK available is 2.8.0. so I suggest updating it.

Best Regards,

Alexis Andalon

Re: eMMC always setting busy bit in cmd1 response

iann — Tue, 06 Oct 2020 13:55:16 GMT

Hi Alexis,

Thanks for getting back to me, this is on a custom board. A previous prototype board worked with a different eMMC chip from ISSI, that board also had quite different power up characteristics for the Core VCC and the I/O VCCQ which we're currently investigating.

I've looked at the latest sdk changes and can see there's a change to the cmd 1 retries which I've implemented in our version. I was using the mmc example as a test.

Is there a way the sdk driver can be changed to issue another cmd 0 after the cmd 1 number of retries has been reached so it will try again after issuing a reset(cmd0) ?

Cheers

Ian

Re: eMMC always setting busy bit in cmd1 response

Alexis_A — Wed, 21 Oct 2020 22:33:12 GMT

Hello @iann,

What you could do is to modify the MMC_SendOperationCondition to include the MMC_GoIdle that will call the CMD0 again.

Best Regards,

Alexis Andalon

Re: eMMC always setting busy bit in cmd1 response

iann — Wed, 09 Dec 2020 12:59:49 GMT

To close this off.

In the end we had to change the emmc part to an ISSI one which has now come up first time with no problem.

Below is the start up sequence showing the handshaking to up gears through the clock speeds.

The SanDisk part had a line in the hardware design manual that it needed the I/O and core voltage in a sequence outside of the normal jedec spec.