Some question about Crazyflie connections

[Yaro]

Hi all,

I've looked into schematics for crazyflie 2.0 and can't understand why batteries are connected in this way to NRF518 with VBAT and VBAT_SINK.

It's used a voltage divider to down voltage from 4.2v to 1.4V but internal ref. is 1.2, how can you measure correctly battery level?
Why VBAT_SINK is connected to NRF518 and not to ground?

About PGOOD and CHG are simply HIGH/LOW output? If you already measure voltage on VBAT, why you need ISET?

I've tryed to use PMV for motor control, but they acts stange. I've used same configuration but with 9.4kOhm resistor instead 10kOhm and 3v3 for input. It work up to 50% pwm and stop working from 50% to 100%. Why that?

Thank you!

[tobias]

t's used a voltage divider to down voltage from 4.2v to 1.4V but internal ref. is 1.2, how can you measure correctly battery level?

There is a possibility to configure internal dividers in the NRF51 as well.

Why VBAT_SINK is connected to NRF518 and not to ground?

If it would have been connected to ground the OFF current would be much higher. Now we can turn the measurement on and off. However the chip will be a little bit powered from these pins when it is OFF so only low current are allowed (that's why we use >100k resistors).

About PGOOD and CHG are simply HIGH/LOW output? If you already measure voltage on VBAT, why you need ISET?

With ISET it is possible to measure the charge current.

I've tryed to use PMV for motor control, but they acts stange. I've used same configuration but with 9.4kOhm resistor instead 10kOhm and 3v3 for input. It work up to 50% pwm and stop working from 50% to 100%. Why that?

PWM or PMV mosfet? Could you provide more information?

[Yaro]

I've tryed to use PMV for motor control, but they acts stange. I've used same configuration but with 9.4kOhm resistor instead 10kOhm and 3v3 for input. It work up to 50% pwm and stop working from 50% to 100%. Why that?

PWM or PMV mosfet? Could you provide more information?

I've used PMV31 mosfet with 9.4kOhm, 100Ohm and 3v3 to PWM a motor, but with freq. above 50% motor stop rotating, I've also tryed 100% pwm, but nothing. I've checked connections and they are good. I've also tryed to analyze signal with a logic analyzer and seems good too. What can be the problem?

[Yaro]

I've tryed again with another microcontroller and found that when I set output to high(output is PWM output, 100% duty) and connect to MOSFET, motor doesn't throttle. I've tryed 2 microcontroller and have the same problem. I've tryed to connect an external source(battery) to MOSFET PWM pin an this time motor throttle at full speed. Where can be the problem?