View Full Version : Big Robot No Brain

08-31-2008, 03:50 AM
I am kinda new to basic stamp My bots are on 75MHz and have video senders
My quesion is when the bot reaches its range limit it can it switch to a basic stamp program
to shut down to a safe mode .keep in mind that these are rather large and powerful.
also to extend my range·can a·75MHz receiver send·pwm comands to a basic stamp and·it be intergated into a hacked transmitter for a homemade relay station
the tx signal is controlled by variable resistors and I need 7 or 8 channels
any one got any idea where·to start with a limited buget and lots of spare parts

Mike Green
08-31-2008, 04:48 AM
You would need to provide a lot more information about your bot to be able to answer your questions.
When you say PWM, what do you mean? That could be standard R/C servo control pulses or something else.
How do you anticipate "switching over"? How would your bot know it's out of range? What are the PWM
signals controlling?

09-01-2008, 02:45 AM
These bots are tank type steering with snowblower trac system and wheelchair motors running at 24 volts with standard hoddy type hitec 75 MHz 8 channel reciever controlling two IFI 883
also the other bots use vantec controllers and one with a robotec controller
standard r/c servo control pulses control these fine and they can be plugged right into the basic stamp just like a servo
letting plenty of amperage to the DC motors thru these controllers
with the video sender power at 5 watt. I geuss you might concider them full sized unarmed battlebots used for survallance
however when the bot reaches it's range limit they somtimes start to behave erratic
It would be nice to have a basic stamp monitoring the receiver and kick over to a program to run a safe shutdown till back in range
I have plenty of robot and they are fine in the range they run in
however out of range is'nt good

Mike Green
09-01-2008, 03:42 AM
How would you have the Stamp monitor the receiver? Does the receiver have a signal quality output?

I think the most direct solution would be for the Stamp to control a series of reed relays that normally connect the outputs of the receiver to their respective motor controllers. The Stamp would use one I/O pin to control a switching transistor that would turn on the relays. The Stamp would somehow monitor the receiver's signal quality output and turn off the relays when the signal becomes too weak. Each servo input would have a pull down resistor that would hold it off when the receiver is disconnected. 8 of the Stamp I/O pins would be connected to the servo inputs. They would normally be in input mode so they're high impedance. Once the relays are turned off, the Stamp would switch its 8 I/O pins to output mode and begin outputting servo control pulses based on some kind of failsafe behavior. The Stamp could also monitor the servo control pulses prior to the switchover. I don't think the Stamp is fast enough to track the servo pulses in "real time", but it wouldn't have to measure every servo pulse on every channel on every cycle of the receiver's 8 channels since the receiver would normally feed through.