M500 & Doodle Labs Compatibility & Socketed Connections

Ivan-Gambit

Two questions regarding (1) Doodle Labs Mesh Rider radio compatibility with the ModalAI M500 & (2) Connecting the ModalAI M500 (if supported) with a socketed Doodle Labs Mesh Rider radio.

I wanted to confirm compatibility of the Doodle Labs radios (nano & mini) with the ModalAI M500 since I'm seeing some conflicting documentation.

The mini-OEM MeshRider Radio on ModelAI's site shows a compatibility list that doesn't include the VOXL Flight, which I believe is the flight controller used by the ModalAI M500; however, the ModalAI Doodle Lab's User Guide does include the VOXL Flight under the supported hardware list.
- mini-OEM MeshRider Radio on ModelAI's site
- ModalAI Doodle Lab's User Guide
Additionally, Doodle Labs mentions integration with VOXL2 which doesn't appear to be the hardware for the ModalAI M500; however, the Doodle Labs documentation doesn't specify whether the Smart Radios support connection with the VOXL, VOXL2, or the VOXL-Flight, but does mention the Qualcomm Snapdragon 821 which I believe IS on the VOXL & VOXL-Flight.

The ModalAI Doodle Lab's User Guide shows additional hardware required for connecting to VOXL Flight, specifically a USB Expansion Board as well as a Power Module. Are these additional hardware required if I purchase a socketed version of the radios (socketed mini linked as example), or can I forgo those extra boards / cables & connect to the socketed ports more easily?

Thank you in advance for your response!

Vinny

Hi @Ivan-Gambit
Wow great job doing your research here on this topic.
Bear with me, I am from the HW Team, but I can at least help explain some of the questions you may have.
Apologies that some areas of our sites are not as updated as others. Generally speaking, if you see the info on our Tech Docs areas, those are the most current. Our sales-front website is updated often too, but can quickly go out of date as we update and bring new features and support to our programs. So I generally would suggest use the Tech Docs section to help minimize any confusion you may have.

That said, we have not tested in all possible Doodle form-factor configurations (such as the socketed ones), but there are a few key attributes about integration with Doodle that are important:

Interface format. We generally use USB, as shown in the Doodle Integration Guide. They do mention some driver support for Ethernet based radios, but we do not have a lot of Ethernet hardware options available, so we advise to use USB if possible. Item MCCA-M0078 is our "simplest" and most straightforward way to get the USB host port from our Voxl-class platforms. If you have other products like modems or WiFi adapters, then you need to make sure yours has an expansion USB port (they all do but wanted to mention it to be sure).
Power: We list our Power Module V3 in the hardware since we know Doodle takes a lot of power. Very few of our USB ports can directly provide enough 5V VBUS power to meet all listed specs/performance results. So, we generally guide customers to prepare for a splice from the power module directly to the Doodle 5V input. Our module provides 30W (5V @6A) in total system power, so that leaves plenty of margin for both the Voxl system and the radio system. If you must minimize cabling and splicing, only our Voxl2 platform with very specific USB plug-in board ports can work with a direct cable as mentioned in these links:
https://docs.modalai.com/expansion-design-guide/#usb-expansion-over-j3--j5
https://docs.modalai.com/cable-datasheets/#mcbl-00068
https://docs.modalai.com/cable-datasheets/#mcbl-00085
But neither of those cables are compatible with a Voxl (M500) or M0048/M0030 plug-in boards due to power limitations. They may "function" and you might get very limited range (if the Doodle can even power up with 500mA VBUS, we do not know since we have not even tried), but you'd more than likely need to provide a spliced cable directly to the power module V3.

Hope that helps you.
If you have more specific Software related topics/questions, let us know and I'll try to get a fellow team member to respond.
Anything hardware related, feel free to tag me directly in any response so I see your message in a timely manner.

Thanks!

Ivan-Gambit

@Vinny , so if I'm understanding everything correctly then

I'll need the following USB board in order to be able to connect to the Doodle Radio: https://www.modalai.com/products/m0078
I'll need to splice power from Power Module V3 to the Doodle Radio which can source the current the radio requires to properly operate

Which brings up the following question, do I need to disconnect the power & ground wires when connecting USB from Doodle Labs radio to the VOXL / VOXL 2 USB Expansion Board with Fastboot v2, or will the Doodle Labs radio automatically draw current from the spliced cable to its power input?

Ivan

Vinny

Hi @Ivan-Gambit
Good questions.
M0078 Tech Docs Reference: https://docs.modalai.com/usb-epxansion-with-fastboot-v2-datasheet/

Yes, if you have a Voxl or Voxl-Flight in an M500, you will need the M0078 PCB to expose the USB host port from J13. You will not use the provided MCBL-00009 in the M0078 kit.
Yes, Voxl or Voxl-Flight J13 port was not designed with Doodle in mind, so you are best to use a splice direct from the power cable. The way to do this is as follows:

Use the D+/D- and GND from the M0078 4-pin JST "J3" to the Doodle USB D+/D- and one GND
use the 5VDC and a GND from the Power Module to the Doodle 5V input and GND.
In your case, you can remove the jumper from M0078 "J2" since you are not using any VBUS from the M0078 USB connector.
If you remove the jumper on M0078 J2, that allows you to use a simple 4-pin JST to JST cable to the Doodle such as https://docs.modalai.com/cable-datasheets/#mcbl-00015 , or convert it to a breakout cable to connect to the Doodle (Sorry I do not know how to advise further since I am not familiar with the socketed versions)
Note: Yes, we have that jumper on M0078 to provide an easy way to access the 5V from the power module, but we did also not design that jumper and the traces with Doodle in mind. It was more for devices needing 1A of USB VBUS, not 2A+ that Doodle requires. You can try it, but you may have limited range at the highest power modes, and most of our cables that you would then use are also 1A limited, so problems like voltage droops/sags may occur with that approach.

The key thing in all of this is to make sure you have a common GND, and the return current for USB will go where it needs and the return current for the 5V will follow it's associated GND return path. Also make sure you do not short VBUS to the 5VDC of your splice if you use that jumper J2. Might be best to just leave it off, but since those pins are "HOT" maybe add a bit of Kapton over them to protect against inadvertent shorts.

If you are hesitant to make splices in the power feed for Voxl, you can see if one of our pre-spliced power cables we offer can give you a jump start, such as: https://docs.modalai.com/cable-datasheets/#mcbl-00211 and then remove the JST to provide what you need on the Doodle side. But, if you need all 4 wires for the I2C port on Voxl, you can start with an MCBL-00001 and then just move contacts from one cable to another.... https://docs.modalai.com/cable-datasheets/#mcbl-00001 There really are a lot of ways to do this (sorry if it's info overload).

I'm happy to review your final solution. If you want some extra support we can email you if you want to share more non-public drawings or such. Just let us know! But, if you are willing to share your setup and pics, it would be faster and you'd be helping others in the same situation

Thanks!