Posted by Jerry Eckert.
Engineer from Looking for a team in Raleigh, NC sponsored by New England Prototype/Brooks Automation.
Posted on 12/15/99 8:55 PM MST
In Reply to: Bandwidth must be limited posted by Joe Johnson on 12/15/99 4:23 PM MST:
: I don't know anything about the sensors, but I suspect that they have increased the number and resolution of the analog in channels just as they doubled the number of PWM outputs.
: If this is true, then I think that the CPU will spend too much time sending data to receive all the data from the joysticks etc.
: If there are 16 8 bit sensors, that would mean 256 bits of info without the start & stop bits. With a loop time of about 20 milliseconds that would mean about 10000 bits per second of data just from the sensors alone.
: Even at 19.2Kbaud, this is a fairly high percentage of time spent just sending data.
Good points, Joe. And thanks for saving me the typing!
For the past two competitions I implemented something similar to the dashboard (sans the fancy graphics) using the debug port on the receiver. In the first implementation of this debug mode I drove the output channels and wrote the data to the debug port. I soon discovered it didn't take much debug output to cause the control response to become noticably sluggish. It didn't require much more to cause the outputs to be disabled by the sanity timers. I finally ended up bypassing the device outputs when debug mode was enabled.
Jerry