PRO
rz90208
USA
Asked
Looking for an inexpensive way to isolate the EZBv4 signal line from the Hitech 805bb servos on my inMoov.
I am think of using 2 Ardunio megas as isolation devices.
Connecting the EZB servo ports to pins 0 - 24 of the Arduino and the servos to pins 30 - 54 of the Arduino
and using the following code (just a quick sketch)Code:
void setup() {
for (int i=0;i<25;i++)
{
pinMode(i,INPUT);
pinMode(i+30,OUTPUT);
}
}
void loop() {
int val = 0;
for (int i=0;i<25;i++)
{
val = digitalRead(i);
digitalWrite(i+30,val);
}
}
I have not tried it yet, thought I would bounce it off the community first.
Your thoughts?
RichardZ
Related Hardware Arduino Due/Mega
Related Controls
EZ-B Connection
EZ-B v4 Info
Good luck
And a lot less time and work.
Opto-isolators are also designed not blow as often as Buffer chips/Arduino go-between boards.
Are you powering the servos via a separate PSU/Battery or only one supply for both servos and EZB’s?
If you use a Arduino to isolate the signal between the EZB and servos, wouldn’t this then just blow the port/s on the Arduino, if this is really the problem??
also, the arduino servo library isn’t to be trusted. If you take a look on the oscilloscope, the way the pwm is generated is kinda hacked and it moves around quite a bit. It’s okay, but I’m not a fan of the pwm is generates. Also, I don’t know if all the ports you wish to use can be servo or pwm read on the arduino.
if you wanted to have another controller responsible for the servos, id recommend connecting the arduino via uart to the ezb and using virtual servos so there’s no analog interpretation. This would be similar to how the scc-32 works.
My first thought was to use opto-couplers but the Arduino solution just seemed so much easier and I have a drawer full of 74LS244's from my TRS-80 days.
Showing my age now!
@CEM
I am using a Switching power supply out of a large Dell Server.
I run the 12v output through 2 12v to 6v DC to DC converts. The 6v powers the EZBs and the Servos NOT through the EZBs.
@DJ
I knew you would have some insight on this.
It just seemed to easy as I have plenty Arduinos Megas on the shelf.
Maybe I am making to much of this. Since no one else is having this issue, just consider it a fluke and wire him back up and move on.
if you look at high quality servos, such as the ezrovot hdd’s, they’ll have a glue like substance on the pcb where the wire is soldered. This prevents the signal wire from hitting the positive wire under stress
im guessing the servos in question don’t have that. Perhaps the preemptive solution is to put some hot glue on the pcb where the wires solder
I do believe your problem could somewhere lies in your power configuration.
Some cheaper DC to DC converters are notorious noisy and has caused me issues in the past. Not to your extent of blowing out ports, but it has caused very strange issues.
Also what current rating are they?
Do you have access to an oscilloscope to look at the 6v DC power lines?
https://synthiam.com/Community/Questions/Ezbv4-D12-23-Not-Working-3158/comments
@cem
Yes, I have a dual trace tektronix scope
Here is the dc-dc converter I am using.
Looks like you have been over everything in your passed posts.
Just curious, but have you reverted to having two battery packs one for servos and one for the EZB controllers. And discounting the Dell PSU and the dc to dc converters, and see if you get this problem??
No I have not. After replacing the servo and the 2 EZB lower boards and have not powered up the Robot.
I have been trying to come up with a way to insure it does not happen again.