Search found 21 matches

by James
Fri Sep 24, 2021 8:21 am
Forum: Velocity and Position Control
Topic: Quadratic encoders - voltage issue
Replies: 6
Views: 16112

Re: Quadratic encoders - voltage issue

Just don't increase both resistors, because the ratio won't change and the signal level issue will persist.
If voltage clamping is an issue, you might want to consider a fast TVS like NXP's PESD3V3, which clamps at 3.3V, so the resistor divider can have a more... relaxed session.
by James
Sat Aug 14, 2021 12:08 pm
Forum: Velocity and Position Control
Topic: Quadratic encoders - voltage issue
Replies: 6
Views: 16112

Re: Quadratic encoders - voltage issue

May I suggest that in future production runs, you replace that 2.2k pulldown resistor, with a 220k one? The voltage divider formed with the 1.2k series resistor would then barely affect the input voltage, and you would still have the input pin referenced to ground (and not left floating) when not us...
by James
Wed Aug 11, 2021 2:37 am
Forum: Velocity and Position Control
Topic: Configuring an MCP236 to use encoders
Replies: 2
Views: 5465

Re: Configuring an MCP236 to use encoders

*bump*

Anyone (other than BasicMicro's Support) that can provide any insight on the configuration of the MCPs?
by James
Tue Jul 27, 2021 10:44 am
Forum: Velocity and Position Control
Topic: Quadratic encoders - voltage issue
Replies: 6
Views: 16112

Re: Quadratic encoders - voltage issue

Please include somewhere in that manual (preferably on the wiring section) that there are 3.4k pulldown resistors connected to the DIN pins, I just ended up having to redesign and rebuild an expansion board to include strong pullups (since my encoders have 100k pullups). And that was after spending ...
by James
Tue Jul 27, 2021 10:43 am
Forum: Velocity and Position Control
Topic: Configuring an MCP236 to use encoders
Replies: 2
Views: 5465

Configuring an MCP236 to use encoders

There is nowhere in the manual nor the datasheet, a detailed explanation of how to setup the controller options to use encoders. I'm referring to pin setups, specifically. For example, one of the possible functions of multiplexed pins 14 and 15 on the DB15 interface, is as channels A and B respectiv...
by James
Tue Jul 27, 2021 6:29 am
Forum: General Discussion
Topic: Need help troubleshooting a burned MCP236.
Replies: 19
Views: 23892

Re: Need help troubleshooting a burned MCP236.

A year later... (... and a lot of family issues...) The controllers are working fine, finally. I did run the tests you suggested before replacing the last two FETs, all turned out OK, particularly the pcb. The in-lab made voltage clamps are beasts, the FAN3111C mosfet gate driver is probably THE bes...
by James
Thu Jul 30, 2020 6:53 am
Forum: General Discussion
Topic: Not able to open port in Jetson TX2
Replies: 2
Views: 3045

Re: Not able to open port in Jetson TX2

Here's what's wrong: Open() fails to open the port, because it returns 0. If you open "roboclaw.py", and check Open() (lines 1030-1035 in my version), you'll see that Open() is supposed to return 1 on success, and 0 if the serial library raises an exception, which in your case it does. You...
by James
Wed Jul 29, 2020 3:51 pm
Forum: General Discussion
Topic: Need help troubleshooting a burned MCP236.
Replies: 19
Views: 23892

Re: Need help troubleshooting a burned MCP236.

Turns out that controller was not repaired properly... We attempted a live test today. The clamps worked, nothing got fried. But the (repaired) controller failed. I used the Studio app to test the controller, with the motors connected but the wheels of the UGV in the air. Minimal mechanical load. Th...
by James
Tue Jul 14, 2020 1:19 pm
Forum: General Discussion
Topic: Need help troubleshooting a burned MCP236.
Replies: 19
Views: 23892

Re: Need help troubleshooting a burned MCP236.

Nope, I'm referring to an idle state. Measured currents and temperatures are on idle, with motors disconnected and the motor PWM set to 0% via the Studio app. I know of the thermal pads, very convenient, very not messy :) I'll see if I can replace the one on the controller I repaired (though I was c...
by James
Mon Jul 13, 2020 2:38 pm
Forum: General Discussion
Topic: Need help troubleshooting a burned MCP236.
Replies: 19
Views: 23892

Re: Need help troubleshooting a burned MCP236.

I went through the wiring and measured some current values. The measurements are made at the controller BAT+ connection. The older MCP230A runs at ~113 mA idle (no motors connected, motor PWM set at 0). The newer MCP236 runs at ~121 mA idle (identical conditions). Supply voltage is 53.7 V (13-cell L...