BiCopter + F3FC + Betaflight

[Frederoo]

Hello!

I got my BiCopter yesterday, put it together, but then ran into Betaflight setup issues. I have everything soldered like in the Build Video (motors on top tabs, servos on bottom) but it seems the left part is refusing to cooperate. The left motor controller is making sounds when I turn the copter, and the servo is not making any movements at all (the other one is countering the movement as expected). That made me think the servo and motor outputs are switched.
Here I ran into a Betaflight/F3FC documentation issue: there seems to be no diagram showing which pad goes to which logical output (1 -> A00, 4 -> A01, T1 -> B01 etc.).
I wonder if anyone else ran into this issue? Or has this tab diagram?

[code]
# resource
resource BEEPER 1 A00
resource MOTOR 1 B00
resource MOTOR 2 A04
resource SERVO 1 A07
resource SERVO 2 A08
resource PPM 1 A01
resource LED_STRIP 1 B08
resource SERIAL_TX 1 B06
resource SERIAL_TX 2 A02
resource SERIAL_TX 3 B10
resource SERIAL_RX 1 B07
resource SERIAL_RX 2 A03
resource SERIAL_RX 3 B11
resource I2C_SCL 2 A09
resource I2C_SDA 2 A10
resource LED 1 B04
resource LED 2 B05
resource SPI_SCK 2 B13
resource SPI_MISO 2 B14
resource SPI_MOSI 2 B15
resource ADC_BATT 1 A05
resource ADC_RSSI 1 A06
resource ADC_CURR 1 B02
resource SPI_PREINIT_IPU 1 B12
[/code]

I played around wyth switching outputs a bot and swapped servo 2 and motor 1: when I live tested the motors, one of them spun up, the other didn’t. In the setup above, none of them do. The diagram/pad mappings would be so helpful…

PS You can see above that I use CPPM, that also needed a pin switch – the default setup in the video uses SBus so R1 Rx pad needed to be swapped with pad labeled 6 as per BetaFlight docs.

[jihlein]

My best guess:

PWM1 A08 TIM1 Ch1
PWM2 A07 TIM17 Ch1
PWM3 B00 TIM3 Ch3
PWM4 A04 TIM3 Ch2
PWM5 B01 TIM3 Ch4
PWM6 A01 TIM2 Ch2
R1 B07
T1 B06
R2 A03
T2 A02
R3 B11
T3 B10
FB A06
SDA A10
SCL A09
Current B02
LED Not Sure
Beeper A00

Note – I haven’t watched the build video in any detail, but it’s important that the servos be on outputs PWM 1/2 and motors be on PWM 3/4, or vice versa, I’m not sure which betaflight prefers. The reason for this is so the internal servo timers and internal motor timers can be independently set, allowing the servos to be updated at 270 Hz and the motors updated with one shot, for example. I “think” the servos should be on PWM 1/2.

[Frederoo]

Thank you so much! This gives me an idea what might be wrong at least – PWM timers. I tried swapping motors/serwos and didnt get far (apart from having that one usable ESC and servo). To be sure I even desoldered the servo to check if it works, and it does. The ESC also works, as it produces the init tune.

So, from Betaflight code:
[code]
const timerHardware_t timerHardware[USABLE_TIMER_CHANNEL_COUNT] = {
DEF_TIM(TIM1, CH1, PA8, TIM_USE_MOTOR, 0),
DEF_TIM(TIM17, CH1, PA7, TIM_USE_MOTOR, 0),
DEF_TIM(TIM3, CH3, PB0, TIM_USE_MOTOR, 0),
DEF_TIM(TIM3, CH2, PA4, TIM_USE_MOTOR, 0),
DEF_TIM(TIM3, CH4, PB1, TIM_USE_MOTOR, 0),
DEF_TIM(TIM2, CH2, PA1, TIM_USE_PPM, 0),
DEF_TIM(TIM16, CH1, PB8, TIM_USE_LED, 0),
};
[/code]

Looks like the PWM channel definitions with associated timers. So, the ESCs should be on the same timer, or different? The current setup wyth one working servo and one functional ESC is:

[code]
resource MOTOR 1 A04
resource MOTOR 2 A07
resource SERVO 1 B00
resource SERVO 2 A08
[/code]

Attachments:

1. 

   BiCopter-BuildVideo-connections.jpg
   

[jihlein]

Here’s your timer mapping then:

[code]
resource MOTOR 1 A04 TIM3 Ch2
resource MOTOR 2 A07 TIM17 Ch1
resource SERVO 1 B00 TIM3 Ch3
resource SERVO 2 A08 TIM1 Ch1
[/code]

This won’t work, all channels controlled by timer 3 have to use the same protocol and timing. I suspect the motor protocol is either too fast of incompatible with the servo, and since both motor 1 and servo one are on pins controlled by timer 3, this creates a problem.

I don’t know how betaflight internally distinguishes between servos and motors, which is going to be critical. But the bottom line is servos need to be on output pads 1/2 or 3/4, and motors the opposite, either 3/4 or 1/2.

Ahhh wait a minute – found this under “Starting PIDSs” on the Bi Copter store page:

resource MOTOR 1 B00
resource MOTOR 2 A04
resource MOTOR 3 NONE
resource MOTOR 4 NONE
resource SERVO 1 A07
resource SERVO 2 A08

So:

Servo 1 to PWM out 2
Servo 2 to PWM out 1
Motor 1 to PWM out 3
Motor 2 to PWM out 4

I don’t know of 1 = right or left, which will be critical.

[RCExplorer – David]

All I did with mine was to change these resources:
resource MOTOR 1 B00
resource MOTOR 2 A04
resource MOTOR 3 NONE
resource MOTOR 4 NONE
resource SERVO 1 A07
resource SERVO 2 A08

[Frederoo]

This does not work for me at all (which I still find strange and unusual). I can start the left motor in the Servo tab, by setting the midpoint value of SERVO 2 low, than high again (after that I have to unplug the power to reset the ESC). I also managed to swap the working servo to the other side, but can’t get all of them to work at once. :/

I did apply all the “Starting PIDs” as per the video, I wouldn’t be writing here if I didn’t.

I’ll try errasing flash and starting over, maybe I did something to another setting. Is it correct if I have the working servo under Servo 3 in the Servo tab? I kind of expected “resource SERVO 1” to map to “Servo 1”. Is that how the smix settings work?

[Frederoo]

Ok, I got the servos working by unsoldering the motor connection and swapping cables. BUT the right motor is still not spinning. I guess from the diagram it is number 2.

[code]
resource MOTOR 1 B00
resource MOTOR 2 A04
resource SERVO 1 A07
resource SERVO 2 A08
[/code]

As you can guess, the erase did nothing to fix the issue. It actually showed motor 5 in the resources (I wondered why @david unset motors 3 and 4 – now I know).

Now, as you can see above, the resources are stock. The problem is I still don’t have control over one motor, and I don’t have anything to swap with, as all the rest works as expected. That got me thinking about the pad to CPU mappings, perhaps motor 5 was actually connected to something? Or maybe auto-detected? I don’t remember what the mapping was, but will errase again to check.

EDIT: So, the defaults after errase are:
[code]
# resource
resource BEEPER 1 A00
resource MOTOR 1 A08
resource MOTOR 2 A07
resource MOTOR 3 B00
resource MOTOR 4 A04
resource MOTOR 5 B01
resource PPM 1 A01
resource SONAR_TRIGGER 1 A06
resource SONAR_ECHO 1 B01
resource LED_STRIP 1 B08
resource SERIAL_TX 1 B06
resource SERIAL_TX 2 A02
resource SERIAL_TX 3 B10
resource SERIAL_RX 1 B07
resource SERIAL_RX 2 A03
resource SERIAL_RX 3 B11
resource I2C_SCL 2 A09
resource I2C_SDA 2 A10
resource LED 1 B04
resource LED 2 B05
resource SPI_SCK 2 B13
resource SPI_MISO 2 B14
resource SPI_MOSI 2 B15
resource ESCSERIAL 1 A08
resource ADC_BATT 1 A05
resource ADC_RSSI 1 A06
resource ADC_CURR 1 B02
resource SPI_PREINIT_IPU 1 B12
[/code]

So, I’ll be trying B01 for the other motor. If this works, I suggest making a new diagram and putting it on the store product page somewhere, probably in the BiCopter + electronics page. 😉 After applying the “Starting PIDs” settings on a clean BetaFlight 3.5 resources look like this:
[code]
resource MOTOR 1 B00
resource MOTOR 2 A04
resource MOTOR 5 B01
resource SERVO 1 A07
resource SERVO 2 A08
[/code]

[jihlein]

@Frederoo – I’m going to suggest that the left servo goes to PWM 1, right servo goes to PWM 2, left motor to PWM 3, and right motor to PWM 4.

I know that this does not match the wiring diagram, but I think it matches the resource map and the motor mixing/servo mixing rules.

It also follows from what what we’ve been using on the dRonin firmware successfully (well almost, we have the left/right motors on 1/2 and left/right servos on 3/4). What this does help prove is the timer assignments are correctly allowing independent servo and motor protocols with a 1/2 and 3/4 split.

Beyond that, I’ll bow out of the betaflight discussion because I’m not familiar enough with the internal workings of the code and may just add to the confusion……

[jihlein]

Just for grins and giggles, I rebuilt betaflight 3.5.0 to include the built in bicopter mixer on F3 targets, and compiled it for the DTFc and F3Fc targets. It fits with taking up too much more flash space. Doing this eliminates the need for the mmix and smix cli changes.

I have a spare DTFc board and I tested with that, and can get proper motor and servo operation in both the servo 1/2 motor 3/4 and servo 3/4 motor 1/2 configurations with only minor changes to the resource allocations.

I’ll check the F3Fc when my kit arrives, hopefully this weekend. This is not, and won’t become, an official part of betaflight, but if it works, I could post the hex file here if desired.

I’m suspicious of the wiring diagram, I really think the servos have to be on 1/2 or 3/4 physical pads with the motors on 3/4 or 1/2 physical pads respectively in order to get the timer allocation correct and the proper protocols going to the servos and motors. Particularly so since there’s another report of a bicopter not functioning correctly.

Until I can check this with a logic analyzer I wouldn’t recommend changing anything until I verify what works and doesn’t work.

[Kevin_Erik]

Awesome work J !
In about a month or so I’ll order a Bi-Copter. Can’t really do too much too fast without drawing wife-agro.

[Frederoo]

Great news @Jihlein! I would be willing to test that build if you share. Or I might look into building it myself, is there a branch on GitHub for that?

About wifes… (translated)
Anna: Why did you buy another copter?
Fred: I wanted to have one that is well designed and actually flies.
Anna: Unlike those that could fly but don’t?

Well, its the fourth day and it still does not. 😛 But I feel we are getting there. 😉

Back on topic, the other motor output does not work (which is not a real surprise for me, but I kind of hoped it would). I’ll be looking carefully at what @Jihlein wrote in the first reply to this topic and try to get both motors on Timer 3. Right now, after swapping wires I do have servos on pads labeled 1 and 2, and motors on 3 and 4.

[jihlein]

Here’s the BetaFlight 3.5.0 firmware for the F3Fc with the restored bicopter mixer. The changes are not on my git repository yet, but I will commit/push them after we know this works. Note the hex file had to be compressed as the straight hex file was too large to attach.

I will post what I think the necessary CLI commands are shortly.

Edit:

Before we charge off in a new direction, please try this test. Reset the F3Fc configuration to defaults, then configure the board as a quadcopter, but change the motor output protocol from oneshot (the default) to 50 Hz PWM. The reason for this is both the motors and servos should respond to this protocol, where the servos can’t respond to oneshot. Then on the motor tab, test each “motor” individually and observe what happens. When slider #1 is activated, does the device attached to physical output pad #1 respond? Same questions for sliders #2 thru #4. This will accomplish a few things. We’ll know that all the hardware is good, and we’ll know what virtual widget (motor or servo) numbers respond to what physical output numbers in the default configuration.

As far as the built in bicopter mixer goes, we can hook this up two ways after selecting the bicopter mixer:

Output 1/2/3/4 <-> left motor/right motor/left servo/right servo

resource motor 3 none
resource motor 4 none
resource servo 1 B00
resource servo 2 A04

or:

Output 1/2/3/4 <-> left servo/right servo/left motor/right motor

resource motor 3 none
resource motor 4 none
resource motor 1 B00
resource motor 2 A04
resource servo 1 A08
resource servo 2 A07

If I’ve got the left/right positions backwards, simply swap the pin resources, or move the physical wires. This mirrors my testing with the DTFc, just substituting the appropriate F3Fc resource pins for the DTFc pins.

Until I get my F3Fc, this is my best guess as to what will get you operating correctly.

Attachments:

1. betaflight_3.5.0_RCEXPLORERF3.zip

[RCExplorer – David]

Oh no. I think I messed up the schematic/pins 🙁
Crap. I’m not home for another week, so I can’t test it.
Ah man 🙁

@jihlein knows what he’s talking about! Try his suggestions.
I’ll see if I can check stuff remotely with the help of Johanna.

[Frederoo]

@jihlein your BetaFlight build seems to work without issues, as far as I could test. 🙂 I copied the recommended config without all the mixes and with my resource mappings and it worked the same as vanilla 3.5 build. Unfortunately…

I think I found the final issue with my BiCopter – there is something wrong with one of the ESCs – it produces the init sound, but does not want to start the motor. I tested both ESCs unsoldered on a PWM servo tester, and the other spun up. So this final issue is probably faulty electronics… :/

Thanks for all the help! @jihlein your advice about timers and the pad map was spot on. Both combinations of servos/motors work as long as they are in pairs on either pads 1/2 or 3/4. I made an updated schematic, and will probably do a better one when I have time next week…

Attachments:

1. 

   F3FC-BiCopter-connections.jpg
   

[jihlein]

ESC maybe out of calibration?

[Author]

Posts