Skip to main content

duty cycle testing



Now that I saw a physical response, I should try to make it similar to how a servo should be controlled.

Servos are actuators that receive (expect) position input (as opposed to motors, which receive speed/intensity input). Simply put, it registers input as pulses, decoding the ratio of high (a "on" signal) to low in a given period as a position value. 

As I am waiting for my servo to be shipped, I will continue to work with the LED light. 

As opposed to my previous setup of having the light turn on every time the request is given, I will have the light turn on and off in a regular pattern until a request is given, upon which the pattern will change for one "cycle" (on-and-off pair).

The on-and-off logic (previously the LED control logic) will be run in a separate thread:

def dCycle(*args):
   global dCVal
   var = 1
   while var==1:
     dutyCycle = dCVal
     GPIO.output(17, GPIO.HIGH)
     time.sleep(dutyCycle)
     GPIO.output(17, GPIO.LOW)
     time.sleep(2-dutyCycle)

This code says that the total "cycle" will be 2 seconds, with "dutyCycle" being the length of time that the LED will be on. The global value "dCVal" will contain the length of time the light will be on. 

In the beginning, "dCVal" will be set to 0.15 seconds:

if __name__ == "__main__":
   global dCVal
   dCVal = 0.15
.
.
.
  thread.start_new_thread(dCycle,())

Every time the request is received, the value of dCVal will be changed to give it a different cycle pattern:

(in request received logic)
     dCVal = 1
     time.sleep(2)
     dCVal = 0.15

The LED will be on for a solid second when requests are received then return back to the short length once that is achieved. 

The time.sleep value of 2 somewhat resembled a setup/hold time in digital logic (reminded me of it, at least)... but not really at the same time. 
Labels:

Comments

Post a Comment

Popular posts from this blog

dabbling with cylon

I'm playing around with Cylon JS whenever I have the time. in order to use the leap motion for control, the hand control will need to communicate with the pc that is connected to the leap motion device (leap motion does not provide an arm/linux driver). it seems that Cylon devices can communicate with each other through socket.io or http, and I am currently playing around with that.
Post a Comment
Read more

interfacing alcohol sensor with the led

Programmed the Arduino to have the alcohol sensor play with the LED display. I had the display show either "open" or "lock" depending on the alcohol sensor level. Here is the result: Notice that this has a very notable flaw with respect to its potential use as a "breathalyzer lock": it stays "open" as long as there is alcohol present, which only then "lock"s. This means that currently, if you leave it alone (no breathing into it), it will keep the device unlocked. This is something I will have to resolve. code used for this: int del = 5000; int gasPin = 0; int value = 0; int lastValue = 0; void setup(){ //  Serial.begin(9600);   pinMode(12, OUTPUT);   pinMode(11, OUTPUT);   pinMode(10, OUTPUT);   pinMode(9, OUTPUT);   pinMode(8, OUTPUT);   pinMode(7, OUTPUT);   pinMode(6, OUTPUT);   pinMode(5, OUTPUT);   pinMode(4, OUTPUT);   pinMode(3, OUTPUT);   pinMode(2, OUTPUT);   pinMode(1, OUTPUT);...
Post a Comment
Read more

alcohol sensor (and some patience)

Soldered the alcohol sensor into something that is connectable: I tried to connect this to the Arduino, as I had the appropriate circuitry, but I did not get any legitimate output from it. 5V going in, 5V coming out with no variations. Nothing seems to be awry in wiring, as the circuit seems to be grounded properly (and the 5V current is flowing).  There are a couple of potential factors as to why I'm not seeing any results: - I'm using a 10k ohm resistor, while some guides (and the datasheet for the sensor) asks for 100-200k. However, there seems to be a good amount of people using 10k and getting at least some kind of result. A batch of 100k ohm resistors I ordered is on its way, so I guess I can try with them when they come. - This site  claims that these sensors take 24-48 hours for its signals to be stable. It also tells me that I should not be powering the sensor directly from the Arduino, which I have been doing, out of concern that the power draw of ...
Post a Comment
Read more