Hi Arram,
Fellow user here.
I am using the Arduino IDE and found that it is true that you have to put a negative in for one motor. You then flip the signs to go in reverse.
Because the motors are mounted in mirror image, they would have had to make two version with opposite wiring. Or make a weird tweak to the board.
Part of robotics is using software to make the simple hardware work.
Thank you for your reply but can you be a little more specific please. Do you mean I have to flip the signs when I am programming in mblock or arduino IDE? Which means simply putting a - in front of one of the motor speeds? For example:
set M1 motor speed -100
set M2 motor speed 100
Or am I missing something? I ask this because I have looked at sample programs and not a single one of them says this simple fact. In all of those programs they set 100 for forward and -100 for backwards.
Hi Arram,
since the motors are mirror-mounted, one of the two motors must be controlled with a negated signal if they are to rotate in the same direction from the robot’s viewpoint. I think, When I work with robotics, I have to cope with it. It is also the intention to understand these relationships. That a 10-year-old can not alone, I understand.
Lego Mindstorms experience is probably not helpful at first. The Mindstorms software is a sequential function chart, mBlock has a procedural programming.
By the way, the mbot Ranger gives a “comfort function” forward / backward / right / left, which takes the position of the motors into account:
In my opinion, it is not necessarily better if things happen in the background, which can not be reconstructed as a beginner.
That’s how I see it.
Maybe it was an example code for another board. MBot Ranger has forward / backward / left / right.
When programming line follower conventionally, it looks like this:
I see what you are saying but in all tutorials I have seen that is not the case. If you have time please see the video in this link. This person is using an orion board just like me, and when they set both motors to 100 it is for forward. If they set it to 100 and -100 it is to turn the bot. There are several other videos that do the same thing and many posts on this forum with orion board examples.
It’s very possible that they swapped the wiring…a lot of people seem to want to take that path. Or, the motors were wired in reverse from the factory at that time. There have been some motor issues and recalls, so things may have changed over time.
It is so often to find example code or comments in code which are outdated or leave out an important detail…such as “hey, we swapped the wiring”.
At first I thought mine was wrong until I realized that the sample code did work and when I examined the code I understood.
I did watch 5 minutes of the tutorial, but he only uses the MOVE commands which take care of the sign for you automatically. Do they use the SET MOTOR command somewhere in the video so I can see what they do?
We hear him speak, we see him programming, but unfortunately we do not know what the robot is really doing - on the other hand, I do not find any examples with rotated signals …
I am sorry the video is long but you need to go to around 14:00 minutes in the video. He starts doing an Orion program. He basically says ‘let’s make the robot go forward’ and he sets M1 to 100 and M2 to 100. He then says ‘lets make the robot turn’ and he sets M1 to 100 and M2 -100.
On my robot, to make it go forward I have to set it opposite and if I change the wiring, as I stated before, it messes up the default program.
Here is a link to a topic in this forum. The person coded a program in mblock for the starter kit to use the remote. Yet again, in this program, M1 100, M2 100 is forward. They did not have to reverse the signs in the program to make it work, which leads me to believe something is messed up on my robot but I can’t figure out what.
Look at Matticus’ reply #16 in [Trouble programming IR buttons in 3.2] (the link you provided).
For key pressed #64, he set one motor positive and one negative. In post #10, someone uploaded a table showing the codes: 64 = ‘^’
So for the ‘^’ button, (presumably forward), he sets one motor positive and one negative.
For code #25 “down arrow”, he reverses the signs.
For 9 (right turn) he sets both negative, and for 7 (left turn both positive).
This is exactly what I do for the mCore as well.
As for Amethyst’s example, her code would still work…sort of…but the buttons would be switched around. She may not have mentioned that she was working that bug out, or she threw together an example without fully testing it…I have done that myself (oh, the shame).
If you’re wondering why they don’t simply switch the wiring for one of the motors, here’s an explanation from a designer’s point of view:
The Orion board can be used to control many things…a robot’s wheels, a powered pulley, or an articulated arm.
In some cases, the motors are mounted such that they must be turned opposite to get the desired effect (robot wheels). In other cases, this might not be true (an elbow motor and a wrist motor of an articulated arm).
If you wire it for one design, it will be backwards for the other.
That is the beauty of software. One board, one motor, one wiring. The programming is used to adjust the system to the task at hand. Otherwise, it would require multiple boards, multiple motor styles, etc.
One of the major advances provided by computers is flexibility.
I watched the tutorial at the 14 minute mark.
The tutor is just throwing together code on the screen…if he downloaded it to the robot he would probably be a bit surprised.
Nobody’s perfect.
By the way…if you want to see my C++ source code for a robot which uses the IR sensor to avoid running off the edge of table (most of the time), I included it below. Only use it on a low table with carpet underneath, because eventually the robot takes a dive.
http://somedisassemblyrequired.com/index.php/2017/01/01/mbot-example-program
Yes I see your point. And I finally verified this by downloading part of a manual for programming the ranger. I found a section of the book that says exactly the same thing you said.
However, not to be a stickler, I have a few issues with the company and the instruction manual included in the kit. Makeblock needs to understand that people buying these kits are probably ordinary middle class people who have a kid that wants to do simple programs. Most of these people will expect to open the box, build the robot, plug it in, download 1 piece of software, and begin.
That has not been my experience so far, and judging by the masses of posts on this forum, and the comments on other forums, many people are frustrated and upset.
Makeblock has issues that range from poor motors (thankfully I escaped that fate so far), to poor instructions, to poor examples.
Dear Makeblock, you need to include the firmware issues AND programming examples for the specific board people have on their bot IN the instruction manual. The manual itself should have at least 5 - 10 basic examples of how to make the bot move. People do not want to sift through forums for days on end looking for things that should be with the product. I do thank all of the people who took time to help me. I will try to forget this horrific experience and hopefully get some joy from programming the robot with my daughter.
I’ve been working with Makeblock products, notably the mBot for a couple of years now, even authored an ebook on it (link) in an effort to start addressing the documentation issues. One of the things I will note, having working with robotics kits from many different manufacturers, is that the manufacturer’s documentation always leaves a bit to be desired. With much of the manufacturing being done in China, there is also a language issue and often the translations from the technical dialect of Mandarin is a daunting task because Mandarin does not translate directly English and vice versa. That being said, the community does a good job of filling in the gaps as best it can.
While I truly understand your frustration (having gone through it myself a few times), I would encourage you and your child to keep at it. It’s relatively easy to write helper functions in Scratch that provide the easy to use functionality that you are asking for and that may be the shortest path to helping your child master programming for the mBot Starter Kit.
I would also observe that one might be cautious about taking a lot of the “tutorials” on YouTube as being canonical. If you are using the same code as the speaker and your robot is not doing what you expect I’ve frequently found it is due to the speaker posting code that they didn’t really test. You are absolutely right to question things, and I would encourage you to continue doing so. We will all profit from that. 
This Christmas, we got an mBot for my girl and the starter robot for my boy from Santa. I think mblock and the Android app all have much better functionality for the mBot, but the starter kit has more room for expansion.
I got an excellent book (Exploring Arduino by Jeremy Blum) before Christmas, and have found that the most useful thing about mBlock is that you can look at the translation to Arduino IDE. Basically, for my son’s starter robot, I do all the programming with Arduino IDE, so he can now run his robot and get distances and speeds via Bluetooth from his tablet (using the Bluetooth Electronics app). It’s a steep learning curve, but the Makeblock hardware is fantastic, and because it is Arduino, the possibilities for expansion are endless. He is getting a voice control module for his birthday, and some additional sensors to improve avoidance.
The way I have it set up now, he can write programs in mBlock, and we can add the translation to our base program so that he can toggle to them from the controller. That way he learns the fundamentals from mBlock, and gets introduced to Arduino IDE.
I know it is frustrating, but the point I am trying to make is that you shouldn’t be discouraged. There is a lot of support on this forum, and the extra work is well worth it,
Hi Arram,
Sincerely sorry for the disappoting on you.
I also want to say thank you since I just notice this either. I find there is still some misunderstanding in the instruction which may mislead users. I will update all the official instructions which include this part. Thank you and thanks for all users to clear this issue.
The instructions on the forum are various and some of the instructions may out of date, I’d suggest that you can visit our learn website for the info of our products or send email to tec-support@makeblock.com if there is any problem. The advantages of the forum is that you can get help from all the users which may have more experience with some robots.