We want to have our drive train speed controllers in brake mode during autonomous and in coast mode during the regular game play. We asked FIRST if we could hook up a spike to a switch to turn the brake/coast mode off and on and they said NO. (custom electronics rule…still trying to clarify.) So we are wondering if it is safe to connect the middle pin of the brake/coast header to a digital I/O signal and ground to the brake pin and 5V to the coast pin. Then depending on what the digital output value is, it will be in either mode.
Only connect to the center pin of the 3 pin header on the Victor to control Brake/Coast with a Digital Output pin on the RC unit. A high output will put the Victor in Coast and a Low will put the Victor in Break Mode. Your PWM cable will connect the two grounds together. Be Careful, some of these pins connect directly to the uP and miss wiring or shorting can damaged the uP. We can not comment on whether it is FIRST legal.
Is there a way to control a Victor Brake/Coast Mode without external electronic circuits or from a Digital Output and be FIRST legal?
In past years, Teams have used a limit switch connected to the Victor Brake/Coast jumper. They then used a servo to control the limit switch. This was legal in previous years but we can not comment on whether this will be legal this year.
It seems that dynamic braking is disabled when the victor recieves no pwm input, (when the robot is disabled in the FIRST competition), regardless of the brake/coast jumper. Is this correct?
Would it be possible to let braking remain active when not recieving a pwm signal in later revisions of the 884?
No. When the Victor 884 does not a have a PWM signal, it looks at the jumper setting. If the jumper setting is Coast Mode, the Victor will remain in Coast. If the jumper setting is in Brake Mode, the Victor will remain in Brake Mode. Be aware that braking is proportional to the motor turning. Thus you can still turn a motor by hand slowly while in Brake Mode but it would be very difficult to turn it fast.
If the brake/coast pin of a Victor is connected to a digital I/O on the RC as described in the Q&A, what state will the Victor be in while the RC is disabled? Can one RC I/O be connected to the brake/coast pins of more than one Victor?
**The Victor will still be controlled by the RC while disabled. Even though the RC is disabled and you can not send the RC any need data, the RC is still running your code and the Digital Outputs are still active.
You can connect 2 Victor’s Coast/Brake pin to 1 RC Digital Output.**