Feasibility check: 5x M0166 (AR0144) tracking cameras on a single VOXL 2

[박민솔]

Hi,

We are planning to connect five M0166 (AR0144, micro-coax) tracking cameras to a single VOXL 2 (not VOXL 2 Mini), and would like to confirm feasibility before ordering hardware.

• Use case: 360° coverage
• Frame sync across all five cameras: required
• Target: 1280x800 @ 30 fps

From the docs and forum threads (topics 5010, 4491, 5130), our understanding is:

• VOXL 2 has only 4 unique CCI buses, so with five AR0144s at least one must use the alternate slave address (0x20) via the resistor change plus an alt-address sensormodule.
• The confirmed 4x AR0144 setup is C27 on M0173 plus one alt-address AR0144 on J8 via M0155.
• Adding a fifth AR0144 on J8 lower (ID4) would put a third AR0144 on CCI1, so we are considering J8 upper (ID5, CCI3) via M0172 J2U instead.

Proposed layout (no ToF):

Sensor ID	Connection	CCI	Slave address
0	M0173 J1 (J6 lower)	CCI0	default
1	M0173 J4 (J6 upper)	CCI1	alt (0x20)
6	M0173 J2	CCI1	default
2	M0173 J5 (J7 lower)	CCI2	default
5	M0172 J2U on VOXL 2 J8 (upper)	CCI3	default

Questions:

1. Is this layout supported, or at least expected to work, with the M0173 kernel config (platform config 1)? In particular, is sensor ID 5 (J8 upper) enabled in that kernel and usable with an AR0144 through M0172 J2U?
2. Is an alt-address (0x20) sensormodule for slot 1 included in the current SDK, or only in the zip shared in topic 5010? Is there an alt-address + fsin variant?
3. Frame sync: can all five cameras be synchronized on GPIO 109? Is the sync line routed to M0172 J2U, and does M0173 J4 (ID1) need any resistor changes (similar to R10/R11 on M0188)? Is an ar0144_fsin_5 sensormodule available?
4. Can ModalAI supply an M0166 with the alternate slave address pre-configured, so we don't have to modify the module ourselves and void the warranty?
5. Are there known throughput limits (CSI / ISP / camera server CPU) for 5x AR0144 at 1280x800 @ 30 fps on VOXL 2?
6. If this layout is not recommended, what is the recommended way to run five AR0144s on VOXL 2 (e.g. M0226 or other adapters)?

Thanks!

[Alex Kushleyev]

Hello @박민솔 ,

Your analysis is spot on. Let me provide answers to your questions:

@박민솔 said:

Is this layout supported, or at least expected to work, with the M0173 kernel config (platform config 1)? In particular, is sensor ID 5 (J8 upper) enabled in that kernel and usable with an AR0144 through M0172 J2U?

Yes, this layout should work. For platform config , J8U slot is enabled for either full 4-lane hi-res camera or a tracking camera is just fine. M0172 or M0181 can be used (upper slot for both) and both patch through the common sync signal (GPIO 109 from voxl2).

@박민솔 said:

Is an alt-address (0x20) sensormodule for slot 1 included in the current SDK, or only in the zip shared in topic 5010? Is there an alt-address + fsin variant?

we will include into the SDK / camera server (the sensormodules will be maintained here https://gitlab.com/voxl-public/voxl-sdk/services/voxl-camera-server/-/tree/master/chi-cdk/qrb5165 ) and shipped with SDK soon.

@박민솔 said:

Frame sync: can all five cameras be synchronized on GPIO 109? Is the sync line routed to M0172 J2U, and does M0173 J4 (ID1) need any resistor changes (similar to R10/R11 on M0188)? Is an ar0144_fsin_5 sensormodule available?

sync is routed to M0172 JU and M0181 JU. However, M0173 J4 (ID1) is missing a resistor (R5) connecting the sync to the camera. Note that M0226 has this resistor installed : https://docs.modalai.com/M0226/#image-sensor-synchronization. We will make fsin sensormodules available for all IDs. If you need to enable M0173, we can provide location of R5 for manual installation.

@박민솔 said:

Can ModalAI supply an M0166 with the alternate slave address pre-configured, so we don't have to modify the module ourselves and void the warranty?

Depends on how many you need. We have a small quantity in stock.

@박민솔 said:

Are there known throughput limits (CSI / ISP / camera server CPU) for 5x AR0144 at 1280x800 @ 30 fps on VOXL 2?
No limits that would prevent you from running 5x AR0144 at 1280x800 30fps. Up to 7 cameras is possible on voxl2, but unfortunately the limit is in the available interposer combinations - in this config two other slots are taken by TOF / Thermal camera (TOF has a different connector and Thermal cameras have different ucoax pinout, incompatible with regular cameras).

This should be pretty quick to test, let me know if you want me to run the test, I can do it later this week.

Any other questions?

Alex

[박민솔]

Hi @alex-kushleyev

Thank you for the detailed answers, this is very helpful.

Yes, we would really appreciate it if you could run the test. Based on your answers, we plan to use M0226 instead of M0173 so no R5 rework is needed. We would also like to add one thermal camera. Since we haven't decided between Lepton and Boson yet, could you test both variants, one thermal camera at a time?

Common: 5x M0166 (AR0144), all frame-synced on GPIO 109, 1280x800 @ 30 fps

Sensor ID	Connection	Camera	Slave address
0	M0226 J1	M0166	default
6	M0226 J2	M0166	default
1	M0226 J4	M0166	alt (0x20)
2	M0226 J5	M0166	default
5	VOXL 2 J8 upper (M0172 J2U or M0181 J2)	M0166	default

Test A: + FLIR Lepton 3.5 on the M0226 Lepton connector (J6), using voxl-lepton-server.

Test B: + FLIR Boson+ 640 on VOXL 2 J8 lower via M0181 J1, with the fifth M0166 on M0181 J2 (J8 upper).

What we'd like to confirm in each test:

• All five AR0144 streams running at 1280x800 @ 30 fps with synchronized timestamps (e.g. voxl-check-cam-sync)
• The thermal camera streaming at the same time
• Approximate CPU load and any dropped frames

A few related questions:

1. The M0153 page says a second camera on M0181 J2 is only compatible with VOXL 2 J7. Is that still the case, or can M0181 J2 on VOXL 2 J8 be used for an AR0144 as in Test B?
2. In Test B, the Boson (ID4) shares CCI1 with ID1 (alt address) and ID6. Is that expected to be fine?
3. We'd like to purchase 2 pre-configured alt-address M0166 units (one for ID1, one spare). How can we place the order?
4. Is there an estimated SDK release for the alt-address and fsin sensormodules for all IDs?

Thanks again!