New SD card for compute module 3

buckethead

Hey, I just got the new compute module 3 and I wanted to add an external 128Gb sd card to it. The sd card already has the preconfigured raspbian image on it from the luxonis website but when I inserted the card it wasn't recognized by the device. Moreover, when I checked the available memory it still showed me that there was only around 16Gb. Any suggestions on how I can get this to work? Thanks 😃

erik

This question has already been answered on Discord. In case anyone is interested, here's the reply from our lead HW engineer:
the thing is that our OAK-D-CM3 come preassembled with the CM3 compute module with 16GB eMMC flash form where the device is booted. If you want to use the uSD card and boot the OAK-D-CM3 from there you must buy the Lite version of CM3, as the same SD interface is used for both eMMC and uSD card.

buckethead

Thanks for the reply. Is there any way to use the micro SD card as a form of additional storage. If not, then what is the purpose of there being a micro SD card slot?

Brandon

Hi buckethead ,

So the trade on the SD-Card interface is that if the SD-Card is to be allowed to be bootable, it needs to be connected to the same physical lines as the eMMC, which then necessitates that either eMMC or SD-Card can be used.

It is possible to put the SD-Card on a different interface connected to the Pi, but this results in the SD-Card not being bootable.

So the decision we made was to make the SD-Card bootable, as this gives folks the flexibility to flash a large SD-Card and boot from it - but this prevents eMMC and SD-Card being used at the same time. The alternate decision would be to make the SD Card usable at the same time as eMMC, but this would prevent the capability to boot from the SD-Card.

And all initial Pi compute module depthai all booted from SD-Card.

A better decision perhaps would have had 2 SD-Card slots so that a bootable uSD card could be used and also an uSD card that works while eMMC is present.

We can send you a Pi CM module without eMMC if you'd like so that you can use the uSD-card slot.

Thoughts?

Thanks,
Brandon

julianaddison

Hi @Brandon,

I'm replying on behalf of @buckethead. We are colleagues. Had sent you an email on 28 July 2021 Subject: [DepthAI CM3 Purchase] Faulty Micro SD Card Reader regarding this as well. Figured you might have missed it.

For context, we also purchased a compute module 3 last year and have been using it. This module came with a micro SD card. On this older device, we were able to swap out the SD card for another 128Gb micro SD card after setting it up with the Raspbian image from the Luxonis website which worked well. However in the recently purchased CM3 module, we are not able to detect any SD card, formatted or otherwise even if it’s for additional storage. We suspected that it was faulty.

We quite like the older device setup which was booting up from the uSD. Would you be able to send us that version - Pi CM module without eMMC so that we can use the uSD-card slot as in the initial Pi CM module setup?

Attached our shipping form from our recently purchased device. We'll be able to return the CM3 device we purchased. Hoping we could do this concurrently as we require the device urgently. Let us know if that works. Thanks.

Brandon

Yes will send. Also I am not finding that email. Typo sorry n my email maybe? Karolina Will reach out.