Remembering a previous value?

i'm having little problem , i'm hoping can help!

what i'm trying create electric melodeon (like accordion). need take pressure value between set of bellows (which have done) , compare atmospheric pressure value (which have done).

then want create midi note depending on pressure value. essentially, if button being pressed, want 1 note if pressure value lower last pressure value, , different note if it's higher.

i'm having trouble getting arduino remember previous pressure value. there technique achieve this?

here's code [there bits of code key matrix, ignore them ]:

code: [select]


int analogvalue1 = 0;        // value read pot
int differencebob = 0;
int oldbob = 0;
int bob = 0;

void setup() {
  serial.begin(31250); // opens serial port, sets data rate 9600 bps
  pinmode(1, output);    //
  pinmode(2, output);    //
  pinmode(3, output);    //
  pinmode(4, output);    //
  pinmode(5, output);    //
  pinmode(6, output);   //
  pinmode(7, input);    //
  pinmode(8, input);    //
  pinmode(9, input);    //
  pinmode(10, input);    //
  pinmode(11, input);   //
  pinmode(12, input);   //
}



void loop() {
 
  bob = analogread(a0) / 6;
  oldbob = bob;
 
  delay (10);
 
  digitalwrite(2, high);
  digitalwrite(3, low);
  digitalwrite(4, low);
  digitalwrite(5, low);
  digitalwrite(6, low);
  delay(5);
 
if (bob < oldbob); {
  if (digitalread(7) == high) {
    sendmidi (0x90, 40, bob);
  }
  if (digitalread(7) == low) {
    sendmidi (0x80, 0x18, bob);
    }}
if (bob > oldbob); {
    if (digitalread(7) == high) {
    sendmidi (0x90, 45, bob);
  }
  if (digitalread(7) == low) {
    sendmidi (0x80, 0x18, bob);
    }}
   
  }

void sendmidi (int cmd, int value, int vel) {
  serial.write (cmd);
  serial.write (value);
  serial.write (vel);
}

quote

i'm having trouble getting arduino remember previous pressure value. there technique achieve this?

store in global or static variable called "previouspressurevalue"

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