WL1837MOD: enumeration problem

Hi,

We will look into it and get back to you ASAP. Please bear with us.

Thanks,

PM

Hi,

Thanks for responding.

Just wanna let you know: there is no short circuit on SDIO_CMD from WL1837MOD side. I've double checked.

Regards,

Andrey.

Andrey,

Can you share your schematic? I will send you a friend request, and you can send it to me via direct message.

BR,

Seong

Seong,

As I've told above schematic is the same as WL1837MODCOM8I and WL18XXCOM82SDMMC.

To be clear: I have WL1837MODCOM8I PCB-003 revision connected via TXS0108E level shifter to the sdhci1 port of MYD-Y6ULG2 EVM.

Pull-up resistors are the same as on WL18XXCOM82SDMMC.

TXS0108E schematic is the same as on WL18XXCOM82SDMMC.

At kernel start I can see SDIO_CLK at both side of TXS0108E. Different frequency during enumeration process.

I can see SLOW_CLOCK on WL1837MODCOM8I. But SDIO_CMD present at 3.3v side of TXS0108E only.

TXS0108E itself works well. I can see on both side SDIO_CLK as well as SDIO_CMD with no WL1837MODCOM8I connected.

SDIO_CMD line resistance from WL1837MODCOM8I side to ground is at about 500 ohm. Is that correct or not?

So I can't understand why SDIO_CMD disappears from one side of TXS0108E only if I connect it to the WL1837MODCOM8I.

Do you have any idea?

Regards,

Andrey.

Well.

It looks like I've met the same situation as described here:

https://e2e.ti.com/support/wireless-connectivity/wifi/f/968/t/797584?WL1807MOD-TXS0108

Quotation: "... we have now 6 of 15 prototypes with "damaged" WL1807 which did not shown on the SDIO bus".

Mine WL1837MODCOM8I is damaged I believe.

Can anybody tell me which voltage levels should be on WL1837MODCOM8I SDIO pins after power-up sequence immediately?

Thanks in advance,

Andrey.

Hi Andrey,

The voltage levels on the SDIO pins should be 1.8V. 

BR,

Seong

Hi Seong,

Thanks for responding.

For mine WL1837MODCOM8I board with floating SDIO_CMD line (disconnected from level shifter ) I see at about 0.07V only on it.

At the same time on SDIO_DATx lines I see 1.8V. (WL_EN is grounded, VBAT is 3.3v, VIO is 1.8v, nothing else).

SDIO_CMD line resistance from WL1837MODCOM8I side to ground is at about 500 ohm.(with no power applied of course)

Can you confirm if WL1837MODCOM8I is broken?

Thanks,

Andrey.

Andrey,

10k pull up resistors must be tied to all non-CLK SDIO signals. Do you have one tied to the SDIO_CMD line?

If you haven't already, please go through the WL18xx HDW checklist and ensure that your custom design follows our guidelines.

BR,

Seong

Seong,

10k pull up resistors are istalled. The same as on WL18XXCOM82SDMMC design.

Went through the WL18xx HDW checklist several times. Everything looks like it should be.

But I observe 0.07V only on SDIO_CMD line don't know why. (BTW 1.8V on all others SDIO lines).

I'm sure it 's a reason why host cann't enumerate WL1837MOD.

Can you advice anything?

Thanks,

Andrey.

Andrey,

If the SDIO_CMD line is floating and has a 10k resistor pulled up to 1.8V, it should be 1.8V. 

I would try changing the resistor out with a new one. If you are still seeing 0.07V here, try replacing the module with a new one. 

BR,

Seong