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1  Using Arduino / Sensors / Sharp IR distance sensor and external ADC? on: March 12, 2014, 06:16:17 am
Hi,

is it worth to use an external ADC with more than 10 bit resolution with the sharp IR distance sensors? Especially for the higher distances where the voltage difference per cm gets very small. Or is the output so shaky that the 10bit internal ADC is fine enough?
Sharp IR data sheet: http://www.sharpsma.com/webfm_send/1487

Thanks
Robert
2  Using Arduino / Networking, Protocols, and Devices / Re: nRF24L01 serial like synchronous bi-directional communication on: February 20, 2014, 01:17:19 am
You may have sender and receiver too close together. Try to have at least one meter between them.
3  Community / Products and Services / Re: Open source, TOF laser rangefinder on: February 19, 2014, 01:08:57 am
I nearly ordered one yesterday. Had it in the cart already. On the website it looks as if they were on stock.
What is the lead time if I order now?

Regards,
Robert
4  Community / Products and Services / Re: Open source, TOF laser rangefinder on: February 18, 2014, 03:33:37 pm
Hi,

Very interesting product and a good explanation.
Will the Sensor work with an Arduino? And can you provide a sketch example?

Robert
5  Using Arduino / Sensors / Lidar-Lite on: February 18, 2014, 01:01:08 am
Hi,

I just found this https://www.dragoninnovation.com/projects/32-lidar-lite-by-pulsedlight project asking for money to back the manufacturing of a TOF sensor. I think this would be a great sensot for hobby robotics - seeing the price of 80$ for a sensor which measures the distance up to 40m with 100Hz.
The I2C interface is 5V tolerant.

Wanted to do some commercial for them. I hope they make it. Would be a great addition for my robot projects. :-)

Robert
6  Using Arduino / Sensors / Re: Arduino Mega 2560 and HacroCam on: January 02, 2014, 01:17:26 am
Hi,

I don't have the software. But I uploaded a custom/enhanced version of the most important a part of it in this topic:
http://forum.arduino.cc/index.php?PHPSESSID=9etnterkc1vvmfnb22fgjlctj7&topic=141081.msg1062759#msg1062759

Regards,
Robert
7  Using Arduino / Networking, Protocols, and Devices / Arduino to Java Serial protocoll with retransmit on: September 11, 2013, 01:01:44 am
Hi,

I am currently writing a serial protocol for my robot. Communication is between the Arduino and Processing.
It will contain a simple checksum a retransmit and a kind of "talk allowance" to prevent collisions because of the half duplex nature of the wireless link.

I didn’t find anything ready to use. If someone has something ready or something to start on I would be glad.
The thing gets more complex than I thought  smiley-roll

Thanks
Robert
8  Using Arduino / Networking, Protocols, and Devices / Re: Shorten Messages sent via serial link on: September 10, 2013, 02:00:08 am
I gave it a short try. Works great for positive integers.
I struggle with reconstructing negative integers and floats on the processing side. I will need to spend some more time on it.
9  Using Arduino / Networking, Protocols, and Devices / Re: Shorten Messages sent via serial link on: September 10, 2013, 12:42:16 am
Thanks robtillaart.

Great answer as usual. I'll give this a try.

Robert
10  Using Arduino / Networking, Protocols, and Devices / Re: Shorten Messages sent via serial link on: September 09, 2013, 08:28:05 am
Well, validation is done implicitly and not completely.

Arduino:
Code:
Serial1 << "#" << _FLOAT(theta,4) << ";" << X_pos << ";" << Y_pos << ";" << PING2cm(PingCM[0]) << ";" << PING2cm(PingCM[1]) << ";" << endl;

Processing:
Code:
if (myString.substring(0, 1).equals ("#")) {
        float[] nums = float(splitTokens(new String(myString.substring(1)), ";"));
          theta=nums[0];
          x_pos=nums[1]; x_pos_MAP = round(Size/2 + x_pos);
          y_pos=nums[2]; y_pos_MAP = round(Size/2 - y_pos);
          lastPingL = nums[3];
          lastPingR = nums[4];
          drawSonar(int(lastPingL), 10, -5, 8);
          drawSonar(int(lastPingR), -10, 5,8);
      }

So if the # ist lost or any number is no longe a falid float - the message will cause an exception and will be droped. But as long as the basic structure isn't changed the message is still valid.

So far I didn't notice bad effects from altered messages. There is a non valid one once in a while. But more often my commands sent from the PC to the robot are dropped because hte robot is currently sending. So I need to implement a kind of "allowance to talk" whcih gets handed over between the two. Some true message validation wouldn't hurt either.
11  Using Arduino / Networking, Protocols, and Devices / Re: Shorten Messages sent via serial link on: September 09, 2013, 08:05:22 am
Quote
Is there a way to submit the data in a more compressed form?
Yes, but you loose the ability to sync messages. If a byte get lost, and that DOES happen, ASCII messages are easy to re-sync. Binary messages are MUCH harder to re-sync.

Do you have some sample code for resyncing. At the moment I do only fire the messages. If they are unvalid I drop them But it might still happen that the message is valid but the sensor reading got changed.
I also still need to implement kind of a handover procedure so that not both sides try to send messages at the same time.

Quote
1.523434
Are 6 decimal places reasonable?
I can certainly cut on this one. Done. I cut it down to 4 decimal places.
12  Using Arduino / Networking, Protocols, and Devices / Shorten Messages sent via serial link on: September 09, 2013, 07:42:14 am
Hi,

I send sensor data from my robot via a wireless link to my PC. There Processing is used to process the data.
At the moment I use Stings to send the messages.

Is there a way to submit the data in a more compressed form?

Example message:

#1.523434;100;-150;15;20;

content:
message type;theta;x-coordinates,y-coordinates;sensor1;sensor2

Thanks
Robert

13  Using Arduino / Sensors / Re: Arduino Mega 2560 and HacroCam on: September 09, 2013, 12:21:31 am
I didn't follow what problems you have with the cam and the MEGA. But as stated my cam didn't work either when I connected it to the mega. It worked with the Uno. Still didn't have time to cross check with the Uno again.
I'll try it in the next days.
14  Using Arduino / Sensors / Re: Arduino Mega 2560 and HacroCam on: September 02, 2013, 12:49:18 am
The demo sketch displays the image exactly once when started. You need to restart it when you want a new picture. At least that's what I remember.
15  Using Arduino / Sensors / Re: Arduino Mega 2560 and HacroCam on: August 30, 2013, 12:43:02 am
You use the 32 Bit Version of Processing? The 64 Bit version doesn't support Serial communication.
Did you put in the correct COM port name?

My guess is that the com port is not correctly connected. Due to one of the reasons above.
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