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RE: [avr-gcc-list] Bug? with switch statement

From: John Theofanopoulos
Subject: RE: [avr-gcc-list] Bug? with switch statement
Date: Fri, 13 Dec 2002 15:37:56 -0500

Try declaring your readPort as an unsigned char

John Theofanopoulos

-----Original Message-----
From: address@hidden [mailto:address@hidden
On Behalf Of Hendrix, Jeff
Sent: Friday, December 13, 2002 2:07 PM
To: address@hidden
Subject: [avr-gcc-list] Bug? with switch statement

I'm compiling the code below with 2002-06-25 release from avrfreaks. I
was originally testing this code on a mega128, the I tried in in avr
studio with the same results. I also tried compiling it to an 8515
target and still get the same results. What's happening is the switch
statement will only ever take the last case. To simulate this, you need
to turn on the high nibble on port C pins (to simulate the pullups), and
then turn off one of the bits in the high nibble. The only time it takes
one of the case paths is when bit 8 is off (0x70), all the other times
it just ignores the other cases. Anyone have any ideas?


#include <io.h>

char ReadKeyPad(void)
   char readPort = 0;
   char curKey = 0;

   // check ROW1
        PORTC = 0xfe;  // turn on pull ups and ground row 1
        readPort = PINC&0xf0;   // check just the high nibble
        switch (readPort) {
        case 0xe0:     // key 1 held down
                curKey = 1;
        case 0xd0:     // key 2 held down
                curKey = 2;
        case 0xb0:     // key 3 held down
                curKey = 3;
        case 0x70:     // key 4 held down
                curKey = 4;

        PORTC = 0;
   return curKey;

int main(void)
        char kp;
        DDRC = 0x0f;
        PORTC = 0x00;

   while (1) {
                kp = ReadKeyPad();
        return 0;
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