CAN ISSUE

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CAN ISSUE

Postby farooq_niaz » Thu May 01, 2014 7:43 pm

I am assembling old quad with DIMU and ESC32. Using QGC1.4 B1 CAN MOT_L is 15 and CAN_MOT_L is 0. ESCS are programmed with r54. Given CAN ID 1,2,3,4 to ESCs.

I had made a CAN cable with 120 resistor at one end. One DIMU I soldered 120 on empty R3 spot.

When I try to arm the ESCs they are not arming. I have not connected power to the ESCs motor side. Each ESCs microcontroller is being powered by 5V from the autoquad's 5V and Ground.

When I try to get resistance from two can terminals (ESCs or DIMU). I am getting very low value of resistance around 1 ohm. I had checked that escs were arming when I use them in PWM mode.

if i disconnect dimu and measure the resistance when all esc are connected to can wire with one end of the wire terminated with 120ohm resistor the resistance is 0.9 ohm.

With dimu not connected the resistance is on R3 on dimu is 120 Ohm???
strange
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Re: CAN ISSUE

Postby bn999 » Thu May 01, 2014 8:13 pm

You have a short somewhere on the bus. Check the CANL/CANH pads on each ESC individually.
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Re: CAN ISSUE

Postby farooq_niaz » Thu May 01, 2014 9:51 pm

Ok found issue.

One of the ESCs CAN header is giving some short circuit around 1 ohm.

When I isolated this ESC and put it on pwm all esc start to arm afterwards. I think the CAN chip is bad.

Now the bus is giving 40 Ohm impedance which is lower than 50 ohm limit. What else should i look for.

Need advice from Jussi as this is a very new ESC and still on the bench.
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Re: CAN ISSUE

Postby chschmid » Thu May 01, 2014 10:45 pm

How many 120Ohr resistors do you have in line?

I had made a CAN cable with 120 resistor at one end. One DIMU I soldered 120 on empty R3 spot.


One is alraedy on the DIMU from factory. Just keep the extra one on the DIMU board (total 2 x 120Ohm) and remove the one on the cable. Check for anything (fine hair ect). I had a bad Crash due to that. The ESCS armed but stopped working midair because the rsistance of the bus was to low.

Cheers
Christof
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Re: CAN ISSUE

Postby farooq_niaz » Fri May 02, 2014 7:23 pm

I have one connected on cable and one i soldered on dimu at r3
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Re: CAN ISSUE

Postby Jdmagoo » Fri May 02, 2014 10:37 pm

farooq_niaz wrote:I have one connected on cable and one i soldered on dimu at r3


Yes that's to many, you only need to add one, either at R3 or on the cable but not both. The DIMU v1.1 already has one installed from the factory so you only need to add one more

Edit: just saw Christof already replied and he is correct
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Re: CAN ISSUE

Postby farooq_niaz » Sat May 03, 2014 3:06 pm

I cut the 120 resistor on the cable. Now with 120 Soldered on the R3 position on DIMU and three ESC connected in parallel to the DIMU on CAN bus impedance is 60Ohm :D


But the fourth ESC is now showing open circuit on the CANL and CANH pins.
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