{"id":148,"date":"2019-10-23T08:26:02","date_gmt":"2019-10-23T08:26:02","guid":{"rendered":"https:\/\/starthardware.org\/en\/?p=148"},"modified":"2020-09-25T21:58:31","modified_gmt":"2020-09-25T21:58:31","slug":"unit-20-my-digital-cat-2-2","status":"publish","type":"post","link":"https:\/\/starthardware.org\/en\/unit-20-my-digital-cat-2-2\/","title":{"rendered":"Unit 20 \u2013 My digital cat 2\/2"},"content":{"rendered":"\n

Let\u2019s program our digital cat. It\u2019s still a way to go.<\/p><\/blockquote>\n\n\n\n

We have to teach the digital pet some things. It should blink with the eyes (LEDs). It should purr when it\u2019s stroked. It should grumble when it is ignored. Let\u2019s start with the blinking.<\/p>\n\n\n\n

(BTW: This is part 2, find Part one here: https:\/\/starthardware.org\/en\/unit-19-my-digital-cat-1-2\/<\/a> )<\/p>\n\n\n\n

Blinking eyes<\/h3>\n\n\n\n

Blinking eyes is actually not that different from the blinking LED example we discussed in the very beginning of that course. The LEDs can be connected to two digital Arduino pins. That means we need the commands pinMode and digitalWrite twice. The code could look like that:<\/p>\n\n\n\n

int ledPin1 = 10;\nint ledPin2 = 11;\n\nvoid setup() {\n  pinMode(ledPin1, OUTPUT);\n  pinMode(ledPin2, OUTPUT);\n}\n \nvoid loop() {\n  digitalWrite(ledPin1, HIGH);\n  digitalWrite(ledPin2, HIGH);\n  delay(5000);\n  digitalWrite(ledPin1, LOW);\n  digitalWrite(ledPin2, LOW);\n  delay(50);\n}<\/code><\/pre>\n\n\n\n
Now, both LED blink always in in the same speed. That is a bit boring, no? We should randomly blink the LEDs. Fortunately, there is a random-command.<\/p>\n\n\n\n
Info: random();<\/h3>\n\n\n\n
The random(maximum)-command creates a random number between 0 and the as argument given number (maximum). This number is never reached. If you write random(5) the random results are 0, 1, 2, 3 and 4.<\/p>\n\n\n\n
Let\u2019s generate a random number between 0 and 500. The eyes (LEDs) should switch off when the random number equals 1. That will create random intervals for eye blinking. Now, we put in a small delay at the end of the program. That will give us the needed break to see, that there is something really happening.<\/p>\n\n\n\n
int ledPin1 = 10;\nint ledPin2 = 11;\n\nvoid setup() {\n  pinMode(ledPin1, OUTPUT);\n  pinMode(ledPin2, OUTPUT);  \n}\n \nvoid loop() {\n  \/\/ LEDs on\n  digitalWrite(ledPin1, HIGH);\n  digitalWrite(ledPin2, HIGH);\n  \n  \/\/ blink\n  if (random(500)==1){\n    digitalWrite(ledPin1, LOW);\n    digitalWrite(ledPin2, LOW);\n    delay(50);\n  }\n  \n  delay(10);\n}<\/code><\/pre>\n\n\n\n
Purring<\/h3>\n\n\n\n
The digital pet should purr when it is stroked. To detect if it is stroked, we will use a digital sensor inside. When you stroke it, your hand will cover up some light and the sensor can detect that.<\/p>\n\n\n\n
But at first Arduino hast to measure the normal light when the pet is not stroked. It can do it when it is connected to the USB but we have to code it. Let\u2019s store that value into the variable lightNormal: lightNormal=analogRead(sensorPin);<\/p>\n\n\n\n
The variable sensorThreshold is used to calibrate the brightness difference when it should start to purr. That is done with if(analogRead(sensorPin)> lightNormal + sensorThreshold){\u2026}. It may be that you have to change the value. Just try out other values if it doesn\u2019t purr.<\/p>\n\n\n\n
That is the code without blinking eyes:<\/p>\n\n\n\n
int sensorPin = 0;\nint sensorThreshold = 20;\n\nint lightNormal;  \n\nvoid setup() {\n  lightNormal = analogRead(sensorPin);\n}\n \nvoid loop() {\n  \/\/ Schnurren\n  if (analogRead(sensorPin)> lightNormal+ sensorThreshold){\n    tone(speakerPin,0.001);\n  } else {\n    noTone(speakerPin);\n  }\n\n  delay(10);\n}<\/code><\/pre>\n\n\n\n
Grumble<\/h3>\n\n\n\n
But what if nobody plays with the pet? When it is ignored for to long, it will play a little melody to get attention. We do it like we did with he blinking eyes. We use a random command. Of course, the pet must not grumble while it is stroked. So we have to connect two conditions. We can do that in the if-statement using the double et-sign (&&).<\/p>\n\n\n\n
int sensorPin = 0;\nint sensorThreshold = 20;\n\nint speakerPin = 9;\n\nint lightNormal;  \n \nvoid setup() {\n  lightNormal = analogRead(sensorPin);\n}\n \nvoid loop() {\n\n  \/\/ Meckern\n  if ((random(10000)==1)&&(analogRead(sensorPin)< lightNormal+100)){\n    tone(speakerPin,1200);\n    delay(100);\n    tone(speakerPin,800);\n    delay(200);\n    tone(speakerPin,1000);\n    delay(200);\n    tone(speakerPin,1200);\n    delay(100);\n  }  \n  \n  delay(10);\n}<\/code><\/pre>\n\n\n\n
If your digital pet should grumble or not is of course up to you \ud83d\ude09<\/p>\n\n\n\n
Here you can find the complete code for the digital pet:<\/p>\n\n\n\n
int ledPin1 = 10;\nint ledPin2 = 11;\n\nint sensorPin = 0;\nint sensorThreshold = 20;\n\nint speakerPin = 9;\n\nint lightNormal;  \n \nvoid setup() {\n  pinMode(ledPin1, OUTPUT);\n  pinMode(ledPin2, OUTPUT);\n  \n  lightNormal = analogRead(sensorPin);\n}\n \nvoid loop() {\n  \/\/ LEDs on\n  digitalWrite(ledPin1, HIGH);\n  digitalWrite(ledPin2, HIGH);\n  \n  \/\/ blinking\n  if (random(500)==1){\n    digitalWrite(ledPin1, LOW);\n    digitalWrite(ledPin2, LOW);\n    delay(50);\n  }\n  \n  \/\/ purring\n  if (analogRead(sensorPin)> lightNormal+ sensorThreshold){\n    tone(speakerPin,0.001);\n  } else {\n    noTone(speakerPin);\n  }\n  \n  \/\/ grumbling\n  if ((random(10000)==1)&&(analogRead(sensorPin)< lightNormal +100)){\n    tone(speakerPin,1200);\n    delay(100);\n    tone(speakerPin,800);\n    delay(200);\n    tone(speakerPin,1000);\n    delay(200);\n    tone(speakerPin,1200);\n    delay(100);\n  }  \n  \n  delay(10);\n}<\/code><\/pre>\n\n\n\n
Wow! That was complicated. Time to tinker something!<\/p>\n\n\n\n
Digital Cat \u2013 Paper Model<\/h2>\n\n\n\n
Get the paper model files from here: Download<\/a><\/p>\n\n\n\n