two electrical questions

[mechanicalbrain]

i wanted to use the accelerometer on the robot but we had one (i thought that i must have lost one becuase as i understand it they work on one axis so what would be the point of sending one). then after looking at the parts list i realised they only sent one. is there something im not understanding? if anyone used them or knows how to wire them please help. my other question involves the operator interface. im making a nice control board and want to make a row of toggle switches (about 6-10) and some push buttons (4 or so) as well as a control device containing 3 potentiometers but the electrical guides first provides only talks about using them on port 3. so... im wondering what i can do to the other ports and how to wire the electrical components to the serial conector (i asume their are other ways than first talks about). the material first provided was this.

[sciguy125]

You can find a schematic of the joystick ports here:

http://www.chiefdelphi.com/forums/sh...ck+schemati c

I recall something about needing pots with a certain value (100k I think). If it's not that value, it won't work.



As for the accelerometer, you can get a datasheet on the first website:

http://www.usfirst.org/robotics/2005/specsheets.htm

Knowing acceleration in one axis is moderately useful. The only thing I can think of off the top of my head is collision detection. If there's a spike in acceleration, you've hit something.

[mechanicalbrain]

thanks but the joystick reference wasnt exactely what i had in mind im just hooking up a bunch of digital switches and i want to know what ports to avoid and how much i can fit in.

[BrianBSL]

What you are probally looking for is http://www.ifirobotics.com/docs/oi-r...de-2-21-05.pdf , specifically pages 7-10 which tell you which ports have which connections. There are a total of 16 digital inputs, and 16 analog inputs. This sort of limits you to 16 switch inputs (if it is a DPST ON-OFF-ON toggle switch, and you want to use both ON's, you need 2 inputs), although we usually have more than that by using resistor networks on an analog (same way the hat works on an analog joystick).

Hope this helps.

[mechanicalbrain]

thanks alot now i just need to figure out the accelerometer....

[BrianBSL]

Originally Posted by mechanicalbrain

thanks alot now i just need to figure out the accelerometer....

What's your question about it? They did only send one, so you can only use it in one axis. What did you want to use it for? It gives an analog 0-5 output so you hook it up to the analog inputs ports on the controller.

We've had some pretty good luck with the Analog Devices (www.analog.com) MEMS stuff (most of their accelerometer's are 2 axis), though we've done a lot more with the gyro's than the accelerometers. www.sparkfun.com sells some boards with them mounted or you can buy the EB's from analog.

[Gdeaver]

The 2005 accelerometer makes a pretty good tilt sensor. Could have been used in the ramp riot game to detect when the robot started on the ramp. Pay attention to the wire diagram for this year's sensor. Red is negative - black is positive and white is signal.

[mechanicalbrain]

the accelerometers ive seen on bots arent being used to their potential. our team is trying to use them to have the robot know where it is on the field for a better autonomous or even autonomous outside of the normal autonomous time

[BrianBSL]

Originally Posted by mechanicalbrain

the accelerometers ive seen on bots arent being used to their potential. our team is trying to use them to have the robot know where it is on the field for a better autonomous or even autonomous outside of the normal autonomous time

Heh, good luck with that. We've done a bit of that and not had a ton of luck (tons of drift). I don't think its for a lack of trying that people haven't really done this much.

[Al Skierkiewicz]

Besides using the digital inputs with switches on the joystick ports, you can switch resistor sets on the pot inputs. If you use the four pushbuttons such that they are shorting out a string of resistors that are the series equivalent of a 100K pot then you can read the values just as you would a pot. We use a modified Radio Shack 2 pole 6 throw rotary switch to make a nice 11 position switch for program sub calls. The 11 positions have 10 9k (90K series resistance) resistors between them with a final 9K in series with the switch. At position 1 the resistance is 99k at postion 11 the resistance is 9K.