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ADC1 problems with Firmware/Hardware issue?

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sam.vanratt
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ADC1 problems with Firmware/Hardware issue?

Hi everyone

Today I checked voltages just to understand what might be wrong in the setup. As the motor looks good AND works in the "diagnose" area when I apply the duty cycle (,20-0,50 tested) just as it should and smooth (,35A at 29V with no load). Current works as well, just the RPM function does not produce a movement but rattles. With the cursor keys the motor does nothing but consuming power, so I didn't fiddle around with them, as I do not know what they should do.

I'm using the "Current noReverse Brake ADC2" setting, which I understand to apply a voltage at ADC1 (in my case a HALL throttle with 0,9V-3.3V output) and have the ADC2 with my brakes connected (low active)

When I'm in the Input Wizard and chose the "Current noReverse Brake ADC2" setting for ADC the ADC1 jumps to 1,34V with no input connected. With a 22k PullDown resistor the voltage sinks to 1,22V. This does sound wrong at start. As I have two identical VESCs I tested the second one with the same app settings and it behaves the same. In addition the ADC1+2 is directly connected to the STM32 so no possible wrongdoing (PCB) here. When I connect the throttle the startup/running problems occur but the motor does not start until it reaches 2,3V.

What am I doing wrong?

 

Is maybe my Firmware (3.40) incompatible to my Hardware (4.10) as I could not explain the biased voltage (1,34V) at startup with fitting setup values from the right firmware.

 

Hope someone can explain the (for me) strange ADC1+2 bias. It might be the key to my stuttering of my BLDC.

 

Cheers

Sam

 

 

sam.vanratt
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I checked the ADC possibilities. Unluckily none seems to work with my Voltage level in, which seems very unlikely/unusual. With a variable resistor (5k Poti) the Current profile works, but the motor spins up in a few seconds (to max RPM) and does not stay at a level of the input. With RTapp on I see the duty cycle rise from 10% to the (max defined) 95%. As the profile name (Current ,....) suggests it seems the uC provides a voltage to detect the current flow and therefore is unable to work with a voltage level. Same applies for Duty cycle or pid that I used.

With the available documentation (Input controls) I do not seem to get further.

Cheers

Sam

Pedelec usage in combination with a GoldenMotor MagicPie3 BLDC

TechAUmNu
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Joined: 2017-09-22 01:27
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Are you actually using the input setup wizard to configure the ADC parameters in VESC tool? You can have it work with any voltage range between 0 and 3.3 with almost any throttle and brake mapping in any mode.

sam.vanratt
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Last seen: 2 months 2 weeks ago
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Hi TechAUmNu,

thanks for your reply.

My first go was of course the Wizard; as it did not show usable results I searched the docu, then source code (nearly unreadably to me even with the remarks) and then trial and error.

I'm using a throttle with 0,8V to 3,2V range (which is detected as long as I don't apply a profile), but as soon as I apply the "current no reverse brake ADC2" profile (or the "current no reverse brake") I receive an offset of 1,34V without anything connected apart from a voltmeter on ADC1+2 and the input get corrupted. Meanwhile I tried every profile possible with no result or some strange behavior as mentioned in the topic.

As I get same result on both of my VESCs it's surely something I (or firmware) do wrong. When I use the testing lab "Duty Cylce", "erpm", "current" the motor runs smoothly as it should (still there's an acceleration issue, I guess because of the high mass and current limitation=>inertio I'd say), so only the throttle (and brake) are ruining a good day.

Cheers and a happy new year 2019!

Sam

Pedelec usage in combination with a GoldenMotor MagicPie3 BLDC

sam.vanratt
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Last seen: 2 months 2 weeks ago
Joined: 2018-11-18 14:09
Posts: 83

Hi all

yesterday I had time to dive into my bike project again. Thanks to a colleague I used an external ST32 debugger to look into the uC what he's doing. After a few minutes of fiddling around it was pretty clear: the stuttering comes from braking all the time (accelerating-braking, accel, braking, a few times a second) AND the 5V pin on my first VESC has been badly soldered and connected with mOhms to a few kOhms resistance depending on "mood". As I had no brakes attached at that time I figured out that

a) no matter what profile I used (PID, Current, ...) the ADC2 was always looked into and used as brake

b) the brake input is used as analogue input

c) no pullup/down resistors attached or in the uC defined at the ADC1 or 2

d) very high noise/influence from the board itself (that's why I had 1,34V open connect voltage which fluttered between 1V and 3V

 

So my first problem with the stuttering was solved (10k pull up Resistor to 3,3V and ADC2 inverted as my digital brake pulls to Ground), just as well as the smooth running.

What's open is the startproblem (short start, (overcurrent?) and then stop from instant startup with no slow start, but for that I'll open another thread.

Cheers

Sam

Pedelec usage in combination with a GoldenMotor MagicPie3 BLDC