Posts made by v_v_ramarao

We are using Voxl2 mini with PMDDL2450 and able to setup hires small (640x480) with a bit rate under 1.5 mbps. PMDDL handles this well enough in 4 MHz (Channel Bandwidth) + 3000 m (Distance) settings on the PMDDL.

1. Despite setting both TX & Rx to 1+2 antenna channels the radio wouldn't enter into MIMO mode if you select any specific modulation method. It switches in and out of MIMO mode only if you select AUTO for modulation setting.

My question is... How to enforce MIMO mode for a specific modulation choice, like BPSK 1/2.

@Vinny
Sure, we shall be in touch during this journey.

@Vinny
Hi Vinny
Thank you for the detailed info and the company view point. I fully agree with you in so far as Microcontroller Evaluation kits are concerned. I opine that the Voxl2 Mini, with its dense layout and complexity (and also with 30.50 mm mounting-hole pitch, a practice on generic flight controllers) is expected to serve deep in to product development phases, at the least up to proof-of-concept stage (like your Starling / Sentinel). Presently, if one wants to use Voxl2 Mini with even one camera the board is un-mountable and is confined to bench testing... unless and until the user comes out with his/her own adaptor/splitter board.

My only submission here is that the state-of-the-art Voxl2 Mini board is qualified to be supplied with a usable camera adaptor / splitter by Modal AI who has gone overboard to supply a ESC-Mini to help speed up the product development. Anyway we are happy with Voxl2 eco system and we will gear up to design a suitable camera adaptor board for Voxl2 Mini.

I once again thank Modal AI team for the excellent support through this forum.

Regards
Rama Rao Valluri

@Alex-Kushleyev
Dear Alex Khushlevyev
Thanks for the detailed mail. We shall do the test as suggested by you. Yes, this is the kind of behavior that we too observed although we have not logged the data in a file for plotting.
It is unlikely that in an open bench test the rising CPU temperature can transfer so quickly the heat energy to the baro chip through convection (air). It must be the power tracks beneath the baro chip helping to transfer that heat energy through conduction (copper+FR4). Anyway it is to your PCB design team to confirm this.

The immediate solution, for the mini users, I think will be one of the following:
A) implement temp compensation in the code.
B) install an external baro with I2C interface.

I once again request you to share the steps to install an external baro (BMP280).

(Talking of PCB layout one more thing needs your immediate attention. On Voxl2 mini with J6 and J7 one has to use your interposer (splitter) board, in which case you can't use that respective main board-mounting hole... It fouls. This is the case with either of the interposer boards, single /dual.. It is road-block to use even a single camera with mini. It is very surprising that the spitter boards are not redesigned yet... A minuscule task to address such a glaring fault, is not undertaken yet)

Thanks
Rama Rao

@Alex-Kushleyev thanks for the quick revert.
The culprit looks like the proximity of baro chip to the power connector (and hence the power tracks beneath).
While we wait for a solution from you for the on-board baro we request you to let us know the steps to add / integrate an external baro (BMP280) on one of the existing I2C ports of Voxl 2 mini board. (We already have a BMP280 based baro with I2C interface, that works on 3.3V / 5V.
Thanks
Rama Rao

@Eric-Katzfey We found that the Baro is erratic only when a camera (in this case IMX214) is connected to J7 using M0076 interpose.
If we remove camera (or disable camera server) the problem disappears. You may note that the J7 connector is located in close vicinity of Baro chip.
This behaviour is identical in all the three Voxl 2 mini boards that we have.
This seems to be a h/w or board layout problem. We are obliged if you confirm.

Our setup is:
Voxl2 mini running PX4 on DSP
ESC mini
Hires IMX214
Tracking OV7251

The Problem:
The drone moves up and down constantly in position mode.

Bench Test:
The on-board Baro readings, when observed in PX4-listener, continuously change (couple of meters over 10 seconds)... the baro-reported temperature gradually increases to 50 deg-c and accordingly the pressure readings decrease. The test is done indoors with Voxl2 mini board in open condition (without enclosure), no propellers.

Request:
We are obliged if you could share the setup info for adding an external baro (BMP280 or similar) with I2C interface.