# Voxl - Snapdragon model and supported camera configurations

Source: https://forum.modalai.com/topic/155/voxl-snapdragon-model-and-supported-camera-configurations
Category: Flight Core and Legacy VOXL (https://forum.modalai.com/category/9/flight-core-and-legacy-voxl)
Tags: voxl
Posted: 2021-03-11 23:45:42 UTC by rgsmith
Replies: 3 · Views: 1344

## rgsmith · 2021-03-11 23:45:42 UTC

Hi,

I'm trying to find some more detail on a few Voxl specs.

* The overview [here](https://docs.modalai.com/voxl-datasheet-functional-description/) specifies that the Voxl uses a Snapdragon 821, but the links point at a Snapdragon 820E. Do both these identifiers refer to the same Snapdragon?
* I'm interested in setting up a camera configuration that is not listed [here](https://docs.modalai.com/camera-connections/#compatible-cameras). I would like to use two stereo pairs + one HiRes - is such a configuration possible? I still don't have a strong understanding of what the MIPI CSI physical layer or Qualcomm Spectra Image Signal Processor can support. 
    * [This](https://www.qualcomm.com/media/documents/files/qualcomm-spectra-isp-infographic.pdf) might not be the right Qualcomm Spectra ISP, but it seems to imply that only three simultaneous cameras can be used. Given that the voxel supports a HiRes + Stereo + Tracking configuration though, does that mean something special is going on with the two stereo cameras?

Many thanks!
~Russ

## Reply by Chad Sweet (ModalAI staff) · 2021-03-12 20:36:59 UTC

The Snapdragon 821 is a speed grade version of Snapdragon 820. The Snapdragon 820E was the version Qualcomm sent to distribution, they're all fundamentally the same. Maybe +/- 5% on max clock speeds

The MIPI-CSI configuration for stereo is a special use case, only supported on a few Qualcomm robotics chipsets. It is not very flexible and only works in the configurations we advertise as supported.

## Reply by rgsmith · 2021-03-15 22:39:58 UTC

Hey Chad,

Perfect thanks, thats exactly what I was looking for regarding the Snapdragon model.

So if I understand correctly, the specialized stereo configuration is a hardware limitation inherent to the Snapdragon? I'm trying to understand if this is a case of 'Qualcomm only supports this configuration' or 'ModalAI only supports this configuration'. Your comment leads me to believe that the former is true, and ModalAI's supported configurations are a result of Qualcomm limitations. I just want to be totally sure I've understood your comment correctly, can you confirm that?

Thanks,
~Russ

## Reply by Chad Sweet (ModalAI staff) · 2021-03-15 22:45:49 UTC

Your understanding is correct, ModalAI's supported configurations are a result of Qualcomm limitations