I am using the Marvelmind navigation system (Indoor Navigation Positioning System (433MHz Kit) Product Code : RB-Mav-01) in conjunction with the Devantech MD25 motor controller (Devantech MD25 Dual 12V 2.8A H-Bridge DC Motor Driver Product Code : RB-Dev-31). The problem is that the highest speed the motor controller can run is 38400, while the Marvelmind navigation system is designed to run at 500,000. The system works, but it takes 3 seconds for the motors to react to commands coming in from the nav system. How can I speed up the motor controller? Or what else should I do? I noticed that the Devantech MD49 24-volt system also has a maximum rate of 38400.
Hi,
Did you try to decrease the baudrate of the RB-Mav-01 to 38400 to match the Devantech MD25 maximum baudrate ?
The default baudrate of the RB-Mav-01 is 500kbps as you have indicated. The baudrate is configurable as explained here
Regards,
Hi,
I did decrease the baudrate of the RB-Mav-01 to 38400 to match the Devantech MD25 maximum baudrate. The system works, but the response time is very slow. It takes the motors on my robot about 3 seconds to respond to commands from the RB-Mav-01. This is way too slow for effective navigation. I am just wondering if there is any way to decrease this response time to something like a tenth of a second or so.
Thanks,
DexterThe baudrate doesn’t seem the one causing the delay issue. An MD25 command can be at maximum composed of 3 bytes. So, even at 38400, it shouldn’t take 3 seconds to respond.
Is the Marvelmind communicating directly with the MD25 Motor Controller ? Is there something in between that could cause this delay ? (a microconctroller for example)
Could you post a clear picture showing your current setup ?
I would like to send you a copy of the wiring diagram, but don’t know how do it from this editor. Yes, there is a microcontroller that could be causing the delay. The Rx (pin 0) of the Arduino Uno is connected to the Tx of the Marvelmind hedgehog. The Tx (pin 1) of the Arduino is connected to the Rx on the MD motor controller. I took a picture of the wiring diagram with my phone…how do I get that photo to you? Should I use an email address? That’s about all the wiring diagram shows…it’s pretty simple. Do you think the Arduino Uno is causing the delay?
An Arduino in between the Marvelmind and the MD25 Motor Driver would indeed explain the 3 seconds delay you have.
What is the baudrate you are using in your Arduino sketch ? Have you tried to increase this baudrate ?
You can click on “Attachements” , “Choose File”, then “Add the file” to add an attachement on your post. (please see attached picture)
The attachment shows my wiring diagram. I have my range sensors hooked up through the Arduino (they are not shown in this diagram) and there is no delay when using them. Is the problem maybe that the Marvelmind is designed to run at 500 000, and doesn’t respond quickly
enough when running at 38400? Let me know if my wiring sketch is unreadable…it’s basically an Arduino Uno, the MD25, and the Marvelmind hedgehog/beacon.
I decided to use a faster motor controller, the MD04 (MD04 24V 20A H-Bridge USB DC Motor Driver P[highlight=#fbfbfb][font=Helvetica Neue, Helvetica, Arial, sans-serif]roduct Code : RB-Dev-81), which goes up to 115200. My question is: What motors should I use with this? Does RobotShop sell compatible motors for this motor controller?[/font][/highlight]
RB-Dev-81 can provide up to 20A at voltages between 5V and 24V. This covers a huge range of motors, so it’s really up to you to determine which motor (torque and rpm) best suit your application. The baud rate does not affect the motors.
Hello,
Regarding the update rate:
- Have you frozen the map, before getting the data?.. Because, even with defaul 38kbps, update rate is ~9Hz or so. With 500kbps, it can be as high 30Hz
BR,
Maxim
Hi,
Since it’s been about 5 months since I looked at this, I’m a little fuzzy on the details, but I think I solved the delay problem by taking out a “delay(3000)” that was in the code.
Thanks for your help,
Dexter
Hello guys,
We didn’t visit the forum, which wasn’t too wise, but, anyway, when you have issues with Marvelmind systems, don’t hesitate to chat with us in real time on https://marvelmind.com/ or drop us email to [email protected]
We will be happy to help.
Kind regards,
Maxim
Marvelmind Robotics