Using M4 with BLDCs - Short How to

[aBUGSworstnightmare]

I have one of the few M4CAN boards.

I was just curious of the full capabilities. So is it possible to use 3 serial type connections (Bluetooth, TX/RX on pin headers, and PC/PC7 sockets), can bus, and 4 pwm outputs? Or are we limited to some degree?

Hi Mullet,
when using CAN for the ESC connection you can have Bluetooth (on the BT connector) and 4 PWM outputs (M5-M8) since this is what the standard firmware with external ESC will give you.

When you are able to modify the firmware by your own you can have:
- CAN ESC
- Bluetooth (BT connector)
- 2 PWM (M5/M6)
and - by reconfiguring PC6/PC7 to UART6 (PC6=UART6-TX, PC7=UART6-RX) you will have an additional UART.
The connector with PC6 can i.e, be used to connect a Spektrum Sat (pinout is made for that), and connector with PC7 gives you a TX line.

The TX/RX on the pin-header is the same as on the BT connector; just a different connector type!

Why do you need 3 serial connections? I know people want to use BT and HOTT together, that's possible on the board if you have a firmware to support it: i.e. a firmware that will allow you to use CAN (for your ESCs), BT, HOTT and 3 PWM signals (i.e. for gimbal control).

So, since I don't have HOTT on my end you guys need to consider what's next as unproven, but:
TELEMETRY_HPORT = 1 --> this will select com 3 for HOTT (= (PC6/M7 used as I/O to the HOTT receiver)

Mennos HOTT firmware either uses com 1 (TELEMETRY_HPORT = 0) = pin J2-9 (HoTT is using half duplex TX line only) or com 3 (TELEMETRY_HPORT = 1) = pin J2-10 (=PC6 = M7)
I have not tested this, but I assume the PWM functionality of PC6 will be disabled if you select TELEMETRY_HPORT = 1.

[Mullet]

Thanks as always for your detailed answers.

Yeah I'd most likely use PC6 to transmit to an OSD instead of HOTT. So it looks like I'll get to be the guinea pig using it for other purposes. That leaves me with M5, M6, and M8. These will go towards a camera gimbal system... maybe the STorM32. Not sure 3 PWM will be enough. I still have 1 PWM left on the actual M4, but I wanted to use that for a buzzer. I might have to tap the extra PWM lines going to the on-board ESCs. Then I'm thinking of using the TX/RX and 5v lines for 3DR Telemetry. No BT. This should make for a nice FC board combo that should do enough of what the AQ6 does.

[aBUGSworstnightmare]

Yeah I'd most likely use PC6 to transmit to an OSD instead of HOTT.

In case of a MavLink OSD you can simply use the TX-Signal from the board; why should you need an extra UART for that?

[Mullet]

With regard to using TX from the board... I'm sure you're referring to just making a Y splitter off the the TX going to BT, which was the same suggestion you made for the BLDC expander board. I suppose I could do that and then have an extra PWM channel for something else.

[funkjan]

I read more or less the whole thread, but still would appreciate, if I can get some help in building up a small FPV quad with 4 brushless ESC's and a 2S Lipo - very light build (3.5g motors and MU-3A 0.7g ESC no BEC)


The hardware I got here is a M4 V2 board and a Kisssys Expansion board.

- What do I have to do to make the M4 capable of running with a 2S Lipo?

- And where and how exactly (which pads to be used) do I connect the 4 brsuhless ESC's (Kisssys has M5-M8 connectors but sorry for such a naiv question I got only 4 motors on a quad so this should be M1-M4?)?

- Is there a ready for download FW version for such a build or can somebody help me out with one?


Maybe I missed anything in the wiki or a thread here? - so any help here or links are welcome.

I already fly a M4 V2 Ladybird build and I got a bunch of bigger copters up to DSLR carrying Octos, but this small Ladybird is by far the one what gives me the biggest fun - love the fast RTH sounds like bees


Thanks in advance!


Jan

[LPR]

Jan

I too like the way a brushed small quad can do a return to home. I have mine set at 12 m/s and I like to fly it high and far away till it's just a dot. Then do a return to home and have is stop just in front of me at the home WP. It's a crowd pleaser.

With your Kisssy expansion board the easiest way to go would be to use the four connection to control your four ESCs.
To use the Kisssy expansion board you need to have the firmware for external ESCs.
The four connection on the expansion board are for ports 5 thru 8.

You can use the firmware wizard to easily find the right firmware.

To use a 2s lipo I would buy a BEC that would give 5 volts to power the M4 when connected to the VUSB connection on the M4 board.

You must also connect a wire from the 2s lipo to the ADC connection so the M4 can adjust the motors thrust to the voltage level of the lipo.

Here's a link to a recent build that's similar to yours.

viewtopic.php?f=40&t=4632&p=34638#p34638

Larry

[Patnet]

Hi Joerg, please can you clarify. Using your extension board with the latest revision, I'm still voltage sensing from the lipo to the ADC on the M4V2. Would that be right? In addition to lipo to your board for power.

Thanks. Working on the build with the one you sold me.

[aBUGSworstnightmare]

Hi Joerg, please can you clarify. Using your extension board with the latest revision, I'm still voltage sensing from the lipo to the ADC on the M4V2. Would that be right? In addition to lipo to your board for power.

Thanks. Working on the build with the one you sold me.

Yes, that is correct!
In case of 2S to 3S supply the connections are:
ADC input on M4: LiPo
LiPo connector on M4BLDC: LiPo
some explanation is here: viewtopic.php?f=40&t=3857&start=30#p28953

In case of 4S to 6S supply the connections are:
ADC input on M4: LiPo
LiPo connector on M4BLDC: external 5V or 6V (recommended) BEC, or 7.2V from LiPo balancer connector (in case one don't wants to use an external BEC)
prove of concept is shown here: viewtopic.php?f=40&t=3857&start=40#p29367

[Patnet]

Got it, thanks. Works great.

[funkjan]

Jan

I too like the way a brushed small quad can do a return to home. I have mine set at 12 m/s and I like to fly it high and far away till it's just a dot. Then do a return to home and have is stop just in front of me at the home WP. It's a crowd pleaser.

With your Kisssy expansion board the easiest way to go would be to use the four connection to control your four ESCs.
To use the Kisssy expansion board you need to have the firmware for external ESCs.
The four connection on the expansion board are for ports 5 thru 8.

You can use the firmware wizard to easily find the right firmware.

To use a 2s lipo I would buy a BEC that would give 5 volts to power the M4 when connected to the VUSB connection on the M4 board.

You must also connect a wire from the 2s lipo to the ADC connection so the M4 can adjust the motors thrust to the voltage level of the lipo.

Here's a link to a recent build that's similar to yours.

viewtopic.php?f=40&t=4632&p=34638#p34638

Larry

Hello Larry,

think that is the slowest reply ever and I realy want to appologize myself for that!!!

But after I did place my post/request here last year my mother past away all of a sudden and I had to stop for several reasons all my RC related activities and forgot my post here completely.

I'm realy sorry Larry about that and again thx a lot for your very informative help!!


Jan