Pololu robotics forum

Re: SSC Problem: Motors Don't Move and red LED

Author: ModMob
Forum: Pololu Servo Controllers
Date: 2012-02-08

Thanks for the response. I don't think I described my problem very well...

I've made sure my grounds are connected and have corrected the position value.

Here's what's happening now: Regardless of the baud rate (a number of tested baud rates as low as 9600) I get a red LED and flashing green LED when I turn the controllers on. But when I connect the reset pin to ground for a moment, my servo goes to the correct position. So after I ground the reset pin momentarily, everything works as expected. I'm wondering what might be causing the need for the reset? Is there some way I can avoid this? Routing another wire to my microcontroller is problematic in my set up.

Thanks,
Sean

Re: Breakbeam Sensor Help

Author: DavidEGrayson
Forum: Electronics
Date: 2012-02-08

I don't have any experience with that sensor, but I can at least point you to resources that you might find helpful.

According to the datasheet, that sensor has an LED and a phototransistor.

It looks like you need to use the red and black wires to power the LED, and you probably need an appropriate current-limiting resistor.

For the phototransistor you might be able to make a circuit like the one in this article (but I'm not sure if it's good):

http://www.evilmadscientist.com/article.php/nightlight

I found this by searching Google for "connect phototransistor to led".

--David

Re: Entering Programming Mode.. FAILED!

Author: DavidEGrayson
Forum: Orangutan Robot Controllers
Date: 2012-02-08

Hello, Dave.

I'm sorry you are having trouble with our products. What is your connection to jay.davey? Are you two working on the same project?

In the future, whenever the programming fails and the red LED comes on, please try to run the programmer's configuration utility and tell us the error message. This will help me to understanding what is happening. The one error message you quoted is correct. The two most common errors that people encounter are that the target VDD went out of range (i.e. the AVR is not adequately powered) or that the programmer didn't receive the expected response when entering programming mode (i.e. the programming cable is not connected).

Since the programmer and Baby Orangutan were both working for you for some time, I think there is probably something about your system or your procedures that causes them to stop working. Could you tell me more about what you are doing? How are you powering the Baby Orangutan, and have you verified the voltage with a multimeter? What was it connected to before you stopped being able to program it? Is it possible you plugged the programming cable in backwards? Do you have anything connected to the programmer besides USB and the 6-pin ISP cable?

I've never experienced a problem like you are describing where it takes multiple tries for AVR Studio to connect to the programmer. This makes me worried that there is something wrong with your USB cable, USB port, or with the electronics the programmer is connected to. It would be good to try just connecting to the programmer in AVR Studio 4 while it is disconnected from everything except USB and it would be good to try different ports and different cables to see if that particular problem goes away.

You said you have Windows XP. Have you installed Service Pack 3?

Just for good measure, could you try measuring the voltage difference between GND and VBUS (+5V) on each programmer and let me know the results, in case there is something wrong with your USB port?

I have two Baby Orangutan 328's and three USB AVR Programmers on order, to arrive tomorrow morning, (Just missed getting them today.) This way, I can run a programming test with virgin devices. If these do not work (which I expect), I will be seriously peeved.

When you get your new devices tomorrow, here is what I recommend doing: Get one new programmer and one new Baby Orangutan, and let us know exactly every step you took to set them up. Simplify things as much as possible; the only thing you need to connect for programming is a power source for the Baby Orangutan. It would be great if you even take of a video of the process so we can see a video of what you are doing.

Please check this out.
I fervently hope the problem is a firmware bug that can be cured by an update.
I have a critical project stalled with people waiting on me because of this problem.
I need a way forward.

I'm sorry you are having so much trouble. We test every board that we ship, and the test for the programmer involves programming a Baby Orangutan B-168. Lots of our customers are using the USB AVR Programmer to program our ATmega328P-based boards, such as the 3pi robot, and Baby Orangutan B-328 and they are generally successful. We've been shipping our programmers with the same firmware version (1.01) for over two years now. We have found some problems with it, and issued firmware updates, but we haven't found any bugs that would affect basic programming of an ATmega328P.

--David

Re: Serial data transmission to PC

Author: Jim Remington
Forum: Orangutan Robot Controllers
Date: 2012-02-08

If sprintf() takes up too much program memory, keep in mind that there is a nice little routine in the avrlibc library called itoa(), which converts an integer to ascii characters in decimal or hex.

itoa(da,send_buffer,10); //will convert to decimal
itoa(da,send_buffer,16); //will convert to hex

you need to #include <stdlib.h>

Re: Breakbeam Sensor Help

Author: NewbieTechie
Forum: Electronics
Date: 2012-02-08

yes

Re: Entering Programming Mode.. FAILED!

Author: dave.wyland
Forum: Orangutan Robot Controllers
Date: 2012-02-08

This is a more serious problem than first appears.

I have a commercial design on the bench at work that uses the USB AVR Programmer programming an Atmega328 in the Baby Orangutan programming configuration. Last week, I was happily programming it using the USB AVR programmer. Yesterday, it stopped programming, giving the usual error indicating that something is unplugged. The programmer connects OK, with a little persistence. But it fails when I attempt to read the serial number. Or anything else.

I bought two USB AVR programmers. Assuming that I had somehow fried the first programmer, I installed the second programmer, including downloading and installing its software and assigning it to COM4. It failed as well.

Next, I tried the programmer on a Baby Orangutan 328 running. the B.O. 328 lights up OK (green LED), and the USB AVR programmer lights up OK - initially - with the green LED on and the yellow LED blinking. This configuration also fails.

Note: Connection to the programmer is flaky, sometimes taking several ties to connect. I am running Windows XP on my work computer using Atmel AVR Studio 4, using assembly language, with code previously developed and being modified for a new design.

Another oddity: The USB AVR programmer presently connected to the B.O. 328 has progressively failed between yesterday and today. This morning, I could still get it to connect to Studio 4, usually with several tries of unplugging and replugging the USB connector. Now, it does not connect at all. The last error I received from the Configuration Utility program (and had received yesterday) was that the programmer had sent a command to the device and received no response back. (I hope I have this correct. I can no longer bring up the programmer even to generate the error.)

I decided to cross-check this whole problem against a Baby Orangutan 328 + USB AVR programmer configuration in a home project that I have been working with for 2+ years. This home project has been working on my desk, unchanged during this time. Last night, I went home to verify that I can still read from the 328. Failed! This is with an untouched hardware configuration sitting on my desk in the form of a Pololu USB AVR programmer connected to the B.O. 328.

But there was a software change. Two months ago, my desktop died, and I got another to replace it. I had to switch to Windows 7 (from Windows XP) , but transferred everything over. As I recall, I re-downloaded Studio 4, and I may have re-downloaded the USB AVR drivers. Studio 4 runs fine, assembling code. I had not verified that programming still worked on the new desktop computer.

I have two Baby Orangutan 328's and three USB AVR Programmers on order, to arrive tomorrow morning, (Just missed getting them today.) This way, I can run a programming test with virgin devices. If these do not work (which I expect), I will be seriously peeved.

Please check this out.
I fervently hope the problem is a firmware bug that can be cured by an update.
I have a critical project stalled with people waiting on me because of this problem.
I need a way forward.

Re: [HELP] Building fastest line follower

Author: DavidEGrayson
Forum: Electronics
Date: 2012-02-08

I'd be happy to answer any questions you have about our products, but we can't choose all your components for you. However I do recommend replacing the Arduino UNO, the L293D, and any clamp diodes with a single Baby Orangutan B-328.

--David

Re: Integrating the MLX90614 w/ the Orangutan SVP 1284p

Author: DavidEGrayson
Forum: Orangutan Robot Controllers
Date: 2012-02-08

For anyone following this thread, cpitts14 has spoken on the phone to both Kevin and me about this problem.

Did you resolve your problem yet? Are you going to get the robot finished on time?

--David

Re: Breakbeam Sensor Help

Author: DavidEGrayson
Forum: Electronics
Date: 2012-02-08

Hello, NewbieTechie.

Do you already know how to get an LED to turn on in general, without involving a sensor?

--David

Re: duty cycle of linear actuators

Author: DavidEGrayson
Forum: Mechanical Design and Actuators
Date: 2012-02-08

Hello, 87jeepwrangler.

I expect that the linear actuators will work fine for your application. We haven't heard of any duty cycle limitations, but you could ask the manufacturer, Iowa Export-Import. Let us know what they say.

--David

Re: Dual, 90-Degree Shaft

Author: DavidEGrayson
Forum: Product Suggestions
Date: 2012-02-08

Thank you for the suggestion, Antony. --David

Re: possible to auto reset on fatal error?

Author: DavidEGrayson
Forum: Pololu Servo Controllers
Date: 2012-02-08

Hello, Waltemus.

I'm glad you were able to solve your own problem in such a clever way. It think it is unlikely that we will release a new version of that board because we have since released the Micro Maestro 6-Channel USB Servo Controller, which is better than it in almost every way. In particular, it has more advanced options for deciding what to do when there is an error, and recovering from errors.

--David

Re: 18V15 SMC -- serial problem?

Author: DavidEGrayson
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

I'm glad that you figured out the problem! --David

Re: Kinetic object controlled by an integrated computer syst

Author: DavidEGrayson
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

Hello, Ezio.

Have you tried asking the creators for some details about how it works? You could ask what components they used in the comments section.

Yes, it is possible to control motors with an Arduino (if you have the additional circuitry required) and it is possible to control an Arduino from a PC. I don't know of any software that does it though.

Are there pivots point having four concentric shafts?

I don't know.

I think you could probably make something work with Arduino Mega and a lot of stepper motors and stepper motor drivers. Stepper motors would be better than servos because servos have a limited range of motion.

--David

Re: 18V15 SMC -- serial problem?

Author: foe
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

Just to close the circle on this ... my serial problems were apparently due to the motor I was using and prossibly a loose ground as well. The 18V15 now works beautifully with my arduino and my better quality linear actuator.

Cheers, David

Re: OO and libs

Author: daubi
Forum: Software and Microcontrollers
Date: 2012-02-08

hm .. if I do not use it than I should not call the constructor.
and the constructor might allocate the memory dynamic ..if that helps.
and I would hope that gcc can remove unused libs part.

but yes this is the general discussion: design principles compared to resource usage.

last time I had to do with embeded programing like this I did it in assembler.
And event than I had 8 KB RAM, but only 1 MHz

Re: TTL to RS422

Author: DavidEGrayson
Forum: Electronics
Date: 2012-02-08

Hello, astondb8.

The Pololu 23201a Serial Adapter does NOT have a MAX232 chip on it. The MAX232 serves a similar purpose, but it is not what we put on our serial adapter.

Please clarify what TTL-to-RS232 adapter you have. Do you have a Pololu 23201a Serial Adapter?

Pololu 23201a Serial Adapter

Please tell me more about your wiring. What did you connect the Arduino's RX to? What did you connect the Arduino's TX to? It sounds like you are successfully powering the adapter, but just in case: how you are supplying 5V to the serial adapter?

I don't know much about RS-422 and I know nothing about this peripheral you are connecting to. Is it possible that the peripheral requires a particular handshaking line to be in a particular state before it will turn on and communicate? Typical terminal programs will do things with the DTR and RTS line when you open a connection. I recommend doing some experiments with Br@y Terminal. It allows you to control the RTS and DTR lines, so you can see if those have an effect. Another thing you could to is measure the voltages on different pins on the standard PC RS-232 output (which works) and compare those to the voltages on the output of your serial adapter.

--David

Re: Serial data transmission to PC

Author: DavidEGrayson
Forum: Orangutan Robot Controllers
Date: 2012-02-08

Hello, Akis.

Please use the [ code] and [ /code] tags (without the spaces) to make your code more readable.

I can see two things wrong in your code:

sprintf(send_buffer,"%d",da);
serial_send(send_buffer, 100);
serial_send("\r\n", 2);

On the second line, you are telling our library to send 100 characters (the entire the send_buffer) but you've only initialized the first couple characters of send_buffer so this will probably result in the microcontroller sending junk to the terminal. To fix this problem you would change the first two lines to:

int length = sprintf(send_buffer, "%d", da);
serial_send(send_buffer, length);

The second problem, and the reason you didn't actually see any junk appear on your serial terminal, is that you are calling serial_send a second time without waiting for the first transmission to finish. I recommend reading the documentation of any library function you are calling. The documentation of serial_send says:

Sets up a buffer for background transmission. ... If serial_send() is called before serial_send_buffer_empty() returns true (when transmission of the last byte has started), the old buffer will be discarded and tramission will be cut short. This means that you should almost always wait until the data has been sent before calling this function again. See serial_send_blocking(), below, for an easy way to do this.

So you have two choices: wait for the first transmission to finish before starting the second, or just combine the first and second transmissions. I prefer the latter because it makes your code simpler:

int length = sprintf(send_buffer, "%d\r\n", da);
serial_send(send_buffer, length);

You could even combine the lines together:

serial_send(send_buffer, sprintf(send_buffer, "%d\r\n", da));

--David

Re: 18v7 Fully Assembled unit failed on first power on

Author: BotBuilderMe
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

When I get home from work, I'll see what that toggle does!

Re: 18v7 Fully Assembled unit failed on first power on

Author: DavidEGrayson
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

If you want to figure out what's wrong with the 18v7, could you post your settings file here, and also a screenshot of the Status tab at a time when you think the motor should be moving but is not?

I have a hunch that you never moved the servo output to the neutral position, so a Safe Start violation is preventing the motor from moving. The safe start feature can be disabled in the "Advanced Settings" tab.

--David

Re: A4988 Stepper 1.5A 8ohm 12V?

Author: RyanTM
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

I'm glad you got it working. What you are describing sounds like the driver is overheating. Can you try lowering the current, or adding a heatsink or fan?

- Ryan

TTL to RS422

Author: astondb8
Forum: Electronics
Date: 2012-02-08

Hi

Firstly, sorry for my English is not my native language.

Regarding my question, I work on an Arduino project on which I have to use an RS422 link.
The microcontroller only coming out of the UART TTL, I must turn this nivau TTL to RS232 converter then I utiliose 232/422 to drive my peripheral.

The connection TTL> 232 is made with a MAX232 (Pololu 23201a)
I supplies 5v and I connect Rx and Tx. (and GND of course)
Then I plug in a standard RS232/RS422 converter, but this arrangement does not work.
If I replace the MAX232 with a standard RS232 PC connection, everything works perfectly with HyperTerminal connection.
So I guess it does not come from my wiring.

If I do not use my converter 232/422 and I loop the Tx and Rx output Max232 (Pololu 23201a) I have sent the return of give on either HyperTerminal Serial Monitor is on the Arduino IDE.

It is therefore obvious that the PC sends a signal that the microcontroller does not send or I miss a signal to open the side RS422 connection.

Have you ever used this type of link (TTL> RS422) and if so, how did you handle this setup?

Thank you for your help

cdlt
Yves

Re: Serial data transmission to PC

Author: konda
Forum: Orangutan Robot Controllers
Date: 2012-02-08

Dear Kevin and all,

First of all sorry for my very late response, but it is the first time after a year that I can dedicate some time in my project.

Based on your previous response, I have created the following program:

#include <pololu/orangutan.h>

char da=120;
char send_buffer[100];

int main()
{
char buf[1];

serial_set_baud_rate(9600);
serial_send("Hi\r\n", 4);

while (1)
{
serial_receive(buf, 1);
while (serial_get_received_bytes() < 1);
sprintf(send_buffer,"%d",da);
serial_send(send_buffer, 100);
serial_send("\r\n", 2);
}
}

As I mentioned earlier, my goal here is to appear the full contents of register "da" to my hyper terminal screen via the serial port.

Unfortunately, the above code displays only the first two digits of “da” (in our case 12) and does not display the third digit (0).

What do I do wrong? Is there any alternative method of writing the above program without the usage of “sprintf” command but only with pololu’s serial command library?

Thank you in advance,

Akis

Kinetic object controlled by an integrated computer system.

Author: ezio1975
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-08

I'm trying to implement a control system similar to what you see in this video
http://www.youtube.com/watch?v=kaO3Jp2O39g
motors can be controlled by a PC through the Arduino?
does anyone know how to do and knows a software through which control motors?
It looks like eight pivot points, each pivot point having four concentric shafts, each shaft having an arm on the front and a stepper motor or servo at the back to position it. If you make it small enough for the arms to be moved by ordinary RC servos you can control those directly from the Arduino. For anything else you would need to add a driver circuit.

Are there pivots point having four concentric shafts?

Thanks
Ezio
www.esedraband.it

Re: Wiring my 1205 Stepper and A4983 Driver to Arduino Mega

Author: herring_fish
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

I was doing some set up testing on the Arduino Mega 2560 with an LCD board on top. I hooked up the VDD wire, which is the next to the bottom pin on the right, to the 5 Volt pin socket on the LCD. It ran fine the first few times but between tests, the VDD wire came off.

I had the VMOT, at 12 volts, off when I hooked it back up. When I did, the LCD shut down. The display stopped right away but it took about 5 seconds for the back lighting to go dark. When I pulled to wire back out, the display came back on and was apparently un-harmed. I plugged it in and pulled it out over and over and got the same shut down response and recovery.

Then I decided to plug the VDD wire into the 5 volt socket at the end of the Arduino board next to pin 22. I got the same issue and I can’t figure out what is going on? Of course the motor won’t work with the VDD wire in or out.

What can I do to fix this?

Re: possible to auto reset on fatal error?

Author: waltemus
Forum: Pololu Servo Controllers
Date: 2012-02-07

It didn't work directly connecting the pad to reset but adding a 0.1 μF capacitor in between did work wonderfully. I made the connection easily detachable like a jumper. It would be nice to see a built in jumper that does the same thing on a future release. Time to heat shrink it and try it out in the air...this should be fun :)

Dual, 90-Degree Shaft

Author: antony.trupe
Forum: Product Suggestions
Date: 2012-02-07

I'd love to see a version of "120:1 Mini Plastic Gearmotor 90-Degree 3mm D-Shaft Output" with the shaft sticking out both sides of the gearbox.

Re: 18v7 Fully Assembled unit failed on first power on

Author: BotBuilderMe
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

I did do that, I set the slide to the middle in the control panel software for the ServoCenter and went into the SMC software and did the Quick Input Setup. Slide all the way to right (higher #) when promoted for full forward and all the way to left for full back.

Back in my ServoCenter software, I set the trigger points for the extend and retract of the actuator. Launch my software project, feed the trigger points and it doesnt extend/retract. Remove 18v7, plug in Syren controller...open the control panel software, set trigger points and open project...feed in the trigger points and the device extends/retracts on demand.

Here's what I am using http://www.dimensionengineering.com/SyRen10.htm I thought the spec sheet on the 18v7 was pretty similar?

Re: 18v7 Fully Assembled unit failed on first power on

Author: DavidEGrayson
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

Did you try using the Quick Input Setup Wizard? What went wrong?

--David

Re: 18v7 Fully Assembled unit failed on first power on

Author: BotBuilderMe
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

I didn't notice it until the part arrived.

I haven't had any luck using signals sent from the ServoCenter card to the controller to make the linear actuator move. I had a Syren 10 arrive today and that worked. With your controller being significantly less expensive, I was hoping to make it work.

Re: 18v7 Fully Assembled unit failed on first power on

Author: DavidEGrayson
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

Hello. I'm sorry for the mistake in the coupon and the extra hassle. I wish you had let me know before placing the order. --David

Re: possible to auto reset on fatal error?

Author: waltemus
Forum: Pololu Servo Controllers
Date: 2012-02-07

I just discovered the pin that lights the red LED is normally high and goes low to light it. I'm going to try soldering a wire to the pad and connecting it to the reset pin.

duty cycle of linear actuators

Author: 87jeepwrangler
Forum: Mechanical Design and Actuators
Date: 2012-02-07

What is the duty cycle of your linear actuators? I couldn't find any technical data on your site that specified duty cycle, and the only thread covering the topic went unanswered link here

I'm considering using one of your linear actuators in place of a servo on a LARGE rc car for the steering. I'd ideally like to be able to drive this thing around for a couple hours at a time while constantly steering when needed.

thanks.

Breakbeam Sensor Help

Author: NewbieTechie
Forum: Electronics
Date: 2012-02-07

Basically I need one generic led to turn on when an object passes though the senor shown on the following link

http://search.digikey.com/us/en/product ... ND/1015177

I figure its pretty simple to do just need direction on how to wire it up.

Re: A4988 Stepper 1.5A 8ohm 12V?

Author: NonaSuomy
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

Well seems like I got it working, I was using the USB to power the 5V to the atmega1284p and the 5v of the pololu driver, switched to the 5V of the PSU and then the stepper started to sing so I shut off the PSU then put in the Multimeter inline with the coil and fired it back up, the meter then stayed stable so I adjusted the pot to 0.7 amps and then hooked it up to the uC digital pins D2 + D3 and ran the sample code.

The stepper happily started spinning at a steady rate.

I left it running to check to see if the 4988 was getting hot but was chilled to the touch.

So I left it running for a few seconds and then it started to sputter and jitter then stop.

Flicked off the power supply for a few seconds then hit it up again and the motor started to spin again but for a shorter amount of time, then the sputter, then jitter then stopped.

Motor never gets hot same with the stepper driver.

Have you seen anything like this before?

Checked the data lines from the uC and see the data flowing with the scope.

See power on the 12V rails and 5V rail.

checked voltage on the sleep/reset pin while running there is just under 5v there, when it quits there is 0.3v.

The stepper coil pins have 0.015v on them when it quits.

Is the driver going into a fail safe sleep of some sort from a problem?

When I put the scope on the stepper coil pins it shows no pulse action just flat lines. when it cuts out and when it's jittering you see it pulse spastically.

*just to note I noticed I didn't have the enable pin on digital pin 4 (had it set to GND) so I change that from this picture and it still did the same thing.
P7200380.JPG

Re: OO and libs

Author: paul
Forum: Software and Microcontrollers
Date: 2012-02-07

Hello,

Now I understand what you are saying, but if that array were part of the object, you would lost a lot of flexibility. For example, the memory used by the read() function would always be in use, even when you are not using the sensors. With our current method, you can make the array a local variable so that it is only used temporarily.

-Paul

Re: MinIMU-9 quiescent current

Author: grahamh
Forum: Other Pololu Products
Date: 2012-02-07

Thanks for the quick reply!
I hadn't realised it would be so efficient, 200uA is more or less acceptable (~400 hours standby, with luck).
I'm considering using the 3v output to supply some of the fussier devices in my design, so I can probably justify the higher power usage.

Re: OO and libs

Author: daubi
Forum: Software and Microcontrollers
Date: 2012-02-07

@david: yes unsigned int *sensorValues,

Re: OO and libs

Author: DavidEGrayson
Forum: Software and Microcontrollers
Date: 2012-02-07

Daubi, I think you and Paul are talking about two different arrays. You're asking about the array that is passed by pointer as the first parameter to PololuQTRSensors::read and PololuQTRSensors::readLine, right?

--David

Re: OO and libs

Author: daubi
Forum: Software and Microcontrollers
Date: 2012-02-07

Regarding the Sensor array ..as mentioned .. I would see it as part of the sensor object. And when I check the init function you got the numbers of pins and from that allocate the right size.
In general you can do exactly the same in C using struct and function pointers for the methods.
And ..it is not about complaining. Right now it is about understanding.

Re: D15V35F5S3 #2111 Thermal Dissipation

Author: bmeslabs
Forum: Other Pololu Products
Date: 2012-02-07

Thanks for the quick reply.

From what I've calculated, my application will use 6.66A at 5V which is hopefully the worst case. Normal operating conditions should be lower, I am expecting around 4A.

But you've answered my real question which is I should probably add a heatsink to the regulator.

Re: Jrk21v3 + LACT4P-12V-20 - USB connection lost during run

Author: DavidEGrayson
Forum: Pololu Motor Controllers and Motor Drivers
Date: 2012-02-07

I'm sorry you're still having trouble even with a different power supply.

If you haven't done it already, could you try unplugging one of the leads of the linear actuator motor (so it can't move) and see if the problem still happens?

It's interesting that your failure rate changed when you switched to a different power supply. I think this means that working on the power supply is a good idea. It sounds like the power supply voltage is dropping at least 3 V (from 20 V to 17 V) while switching directions. I think this is the root of your problem, and there are two things you can try to reduce it:

You could try adding capacitance between the jrk's GND and VIN lines. A few hundred µF would probably be OK, but since you have a 22000µF capacitor you might as well put it there and see if it helps. It should be mounted close to the jrk.
Try using the brake duration parameter. If you set it to a value that is large enough, it would prevent the jrk from driving the motor while the motor is moving in the opposite direction. I would set it to something big like 1000 ms at first to see if that helps, but you'll probably want to try reducing it later so you can get better control of the motion.

It sounds like the cables between the power supply and the jrk are only 0.4m, which should be ok.

You said your max acceleration is 15, but what is the PID period?

--David

Re: D15V35F5S3 #2111 Thermal Dissipation

Author: jan
Forum: Other Pololu Products
Date: 2012-02-07

Hello.

First off, you have the right part number (#2111) for the 7-amp version, but you have the product name for the 3.5-amp version. Anyway, the power is limited by overheating, so at the upper limit of the output current, the module will get very hot, with the hottest parts approaching 150 degrees C. I do not know what kind of tolerance you have on that 7A load, but I would be nervous using this regulator without carefully characterizing it in your application. You should also keep in mind that the efficiency and heating distribution are not always the same.

- Jan

Re: Beginner problem - Sequence with autohotkey

Author: DavidEGrayson
Forum: Pololu Servo Controllers
Date: 2012-02-07

I'm glad you are making progress. If the red LED is on all the time it probably means that either you turned it on in your script or an error occurred. Could you check your script for "led_on" commands and check the Maestro Control Center's Errors tab?

--David

Re: Motor Driver Heat Sinks

Author: jan
Forum: Product Suggestions
Date: 2012-02-07

Are you saying you have 330 uF on the motor driver outputs? That would definitely not be appropriate, and it could account for some of your motor driver overheating (it might also kill those caps soon). I think the only legit way to deal with the singing is to use a PWM frequency that's past what you can hear (typically 20 kHz).

- Jan

Re: Encoder Wheels

Author: jan
Forum: Product Suggestions
Date: 2012-02-07

I don't understand what you're saying. (I'm saying that to offer a full encoder solution, we need several components, including motors with the shafts out the back. Since we already have that motor part solved, we are selling them since some customers can make their own encoders. We're still going to work on our encoder solution.)

- Jan

D15V35F5S3 #2111 Thermal Dissipation

Author: bmeslabs
Forum: Other Pololu Products
Date: 2012-02-07

Good Day,

I am looking to use the D15V35F5S3 #2111 voltage regulator to power a devices which draws 35Watts (5V at 7A). According to the specification sheet I read that the regulator has a 90% efficiency in this range meaning I will have 40W input, and the regulator will consume 5Watts.

Without any heatsink on the regulator and assuming the device will operate at room temperature, how hot will the regulator get.

Thanks.

Re: SSC Problem: Motors Don't Move and red LED

Author: jan
Forum: Pololu Servo Controllers
Date: 2012-02-07

Hello.

Your post has several statements that make me think you might have some fundamental misunderstandings or bad approaches. For instance, what do you mean by "I’ve found the correct baud rate (based on LED feedback)" when you don't know what the resulting LED pattern indicates? In any case, you should determine the appropriate baud rate and then possibly confirm you are actually sending what you think you are with an oscilloscope or similar tool. The solid red LED with flashing yellow means the servo controller thinks the baud rate is too slow. It looks like you're trying to send stuff at 38400 bps, which would definitely not be too slow, so it would be nice to verify what you are sending; do you have access to an oscilloscope?

Other troubling statements are "I only have the serial input wired" and "powering the Pololu controller from the same source as the Maple (common ground)". You definitely need to have the grounds connected for the serial input to mean anything, and connecting the grounds is not the same thing as using the same power source. But, you're getting responses from the servo controller (based on the LEDs), so I think you're actually doing something a little differently than you described.

Finally, your "arbitrary for testing" position you are sending is not a valid position; if the rest of your system were to work, it would probably lead to a damaged servo.

I recommend that you start with the Mini SSC II protocol, which is simpler (note that you'll have to use a lower baud rate), try to confirm what your serial line is actually doing, and make sure your electrical connections make sense. If you are not sure or have no progress, you can post a picture or schematic of your setup here.

- Jan

SSC Problem: Motors Don't Move and red LED

Author: ModMob
Forum: Pololu Servo Controllers
Date: 2012-02-07

I’m having a problem getting my Pololu Micro Serial Servo Controller working. I’m using it with a Leaflabs Maple with the Pololu protocol. I’m not able to move any of my Hitec HS-645MG servos.
I’ve found the correct baud rate (based on LED feedback) but once I try to send bytes in the main loop I get a solid red LED and a flashing yellow LED. I’ve read the user’s guide and I’m sending the bytes as per the protocol (start byte, device ID, command, servo num, data1, data2).

Would anyone be able to tell me what a solid red LED with a flashing LED yellow specifically means?

Additional set up details: I only have the serial input wired. The controller and servos are powered from the same 6V regulated supply. The serial input from the Maple will be at 3.3V for high. The Maple’s max baud rate is 115200.
I’ve tried various things like changing the baud rate, different delays and powering the Pololu controller from the same source as the Maple (common ground). All these things had no influence.
Thanks,
Sean

void setup() {
Serial2.begin(38400);
pinMode(29, OUTPUT); //LED for making sure program loaded correctly
delay(1000);
}

void loop() {

unsigned char buff[6];

buff[0]=0x80;//start byte
buff[1]=0x01;//device id
buff[2]=0x04;//command number
buff[3]=0x01;//servo number
buff[4]=0x00;//data1... arbitrary for testing
buff[5]=0x0F;//data2...arbitrary for testing

for(int i=0;i<6;i++){
Serial2.print(buff[i],BYTE);
}
digitalWrite(29, HIGH);
}

Re: Beginner problem - Sequence with autohotkey

Author: al777
Forum: Pololu Servo Controllers
Date: 2012-02-07

When i opened the cmd, i realized that i need to start the device script, i must have missed this part, sorry.

So, i made it, but for some reason, the red LED keeps on all the time, maybe my servos are drawing too much current, and this kinda resets the device,
that is strange because when i start the sequence using the Maestro Control Center, i do not get the red LED.

Okay, thank you very much for you help, i am goingo to study a little more and see what can i do.

Regards,

Felipe.