RoboticsGeneral

Question about the Hexapod Robot Kit

userHead Piero78 2012-06-08 18:35:09 9142 Views8 Replies
Hi! I've a question about the electronic control of the Hexapod Robot Kit.
If I use 18 [u][b]6V[/b][/u] servo motors, can I use ONLY the [url=http://www.dfrobot.com/index.php?route=product/product&path=35_38&product_id=655]DFRduino mega2560 V2.0[/url] with the [url=http://www.dfrobot.com/index.php?route=product/product&path=35_39&product_id=339]Mega IO Expansion Shield For Arduino Mega V1.2[/url]? Can I connect all servo motors directly on the Mega IO Expansion Shield For Arduino Mega V1.2 without the 2 Servo driver boards?
Thanks!
2012-06-15 11:57:44 In our kit we are using the CDS Servos which are controlled through serial. This makes it a lot easier on the MEGA since it only has to send out serial strings to the servos. If you use regular servos, the Arduino Servo library is simulating a PWM which uses some delays, this will cause a whole lot of clock cycles for 18 servos. That is why we switched to the CDS servos, they offer much more accuracy, and it allows the MEGA to continue running its program.



userHeadPic Hector
2012-06-15 04:11:33 Ok, thanks!

But in your kit you use this solution.

userHeadPic Piero78
2012-06-13 09:56:36 Hi Piero,


Yeah, I would expect the MEGA to operate a bit slower for a program which is using so many servos, but I have never tried...So I'm not sure at what point you might start to feel like your MEGA is feeling laggy...I will ask around see if anyone else has experience with this.
userHeadPic Hector
2012-06-12 19:43:47 Ehm, I explain, [u]I don't want use the servos of the kit[/u], I want to use others standard [u][b]6V[/b][/u] servors.
I want to use 2 external power, one for the Mega and one for the expansion shield (and servos connected to them).

This topic is to know if, in this situation, I can connect all servos directly to the expansion shield.

[quote]You could connect them to the MEGA expansion shield and operate them, you will need to provide external power to the servos through the power terminal on the expansion shield, the power provided by the MEGA would not be enough to drive so many servos.
[/quote]

Ok, this is the response I want.  ;)

Another question, Ive red on the Net that it should be delaies to execute commands by servos. Do you know this problem with mega+expansion?

Thanks!
userHeadPic Piero78
2012-06-12 11:17:26 no.  These servo are digital servo which uses half duplex RS485 as communication protocols. You will not be able to driver the servo directly without the driver board. userHeadPic R2D2C3PO
2012-06-12 11:07:43 Hi Piero,


my bad...


You could connect them to the MEGA expansion shield and operate them, you will need to provide external power to the servos through the power terminal on the expansion shield, the power provided by the MEGA would not be enough to drive so many servos.


Just make sure the servos are standard S+- style servos

userHeadPic Hector
2012-06-11 19:50:29 Ok, the servos of your kit are 7.2V servos, I understand. But, if I will use 6.0V servos, can I connect them directly on the board? This is my question.

Thanks!
userHeadPic Piero78
2012-06-11 14:18:07 Hi Piero,


No, the Servo's provided with this kit require that you use the Servo driver boards. These servos are not like traditional servos. Also, connecting them directly to the IO Expansion shield would not provide enough power for all the servos to function properly.

userHeadPic Hector