[SOLVED] Atmega644 - problem with digital read on pins 24 (D18) and 25 (D19)

Using Arduino Microcontrollers
1

Hi,

I'm try to read the state of each switch on a DIP switch.

void setup(){
pinMode(19, INPUT);	// Set pin to input
pinMode(18, INPUT);		// Set pin to input
pinMode(15, INPUT);		// Set pin to input
digitalWrite(19,HIGH); 	// enable internal pull-up
digitalWrite(18,HIGH);		// enable internal pull-up
digitalWrite(15,HIGH);		// enable internal pull-up

if (digitalRead(19)==LOW)
        volumeCtrlLocked=true;
else volumeCtrlLocked=false;
if (digitalRead(18)==LOW)
	outputLocked=true; 
else outputLocked=false;
if (digitalRead(15)==LOW)
	phaseLocked=true;
else phaseLocked=false;
}

The digitalRead on pins 24 (D18) and 25 (D19) always returns LOW for some reason. D15 responds as expected, it only returns LOW when the switch is closed.
It also works fine when I connect the DIP switch to some other digital pins, instead of D18 and D19.

I'm using the Sanguino software and upload the code using an Uno. At first I thought that it might have something to do with the JTAG interface being enabled, but the problem still occurs after disabling it by setting the fuses.

The reason that I want to use this pins is that I have a PCB that connects the DIP switch to these pins, so using other pins in no real option for me.
I must be missing something here...

EDIT: I attached the boards.txt file with the settings of the fuses and other settings as well.

boards.txt (1.9 KB)

2

I ran this sketch based on yours:

bool volumeCtrlLocked, outputLocked, phaseLocked;

void setup(){
  
  Serial.begin (115200);
  
  pinMode(19, INPUT);	// Set pin to input
  pinMode(18, INPUT);	// Set pin to input
  pinMode(15, INPUT);	// Set pin to input
  digitalWrite(19,HIGH); 	// enable internal pull-up
  digitalWrite(18,HIGH);	// enable internal pull-up
  digitalWrite(15,HIGH);	// enable internal pull-up

  if (digitalRead(19)==LOW)
    volumeCtrlLocked=true;
  else volumeCtrlLocked=false;
  
  if (digitalRead(18)==LOW)
    outputLocked=true; 
  else outputLocked=false;
  
  if (digitalRead(15)==LOW)
    phaseLocked=true;
  else phaseLocked=false;
  
  Serial.print ("volumeCtrlLocked = ");
  Serial.println (volumeCtrlLocked, DEC);
  Serial.print ("outputLocked = ");
  Serial.println (outputLocked, DEC);
  Serial.print ("phaseLocked = ");
  Serial.println (phaseLocked, DEC);
}

void loop () { }

Jumpering together pins D18 and D19 worked as expected on my Sanguino board.

My fuse settings are:

Signature = 0x1E 0x96 0x0A 
Processor = ATmega644P
Flash memory size = 65536 bytes.
LFuse = 0xFF 
HFuse = 0xDC 
EFuse = 0xFD 
Lock byte = 0xFF 
Clock calibration = 0x84

Note that changing boards.txt doesn't change the fuses on the actual chip unless you re-burn the bootloader.

3

Thanks, I did re-burn the bootloader. I`ll try your fuse settings later on today.

4

At first I thought that it might have something to do with the JTAG interface being enabled, but the problem still occurs after disabling it by setting the fuses.

this seems like a likely theory. Are you sure you have the fuse settings correct for disabled JTAG?

5

westfw:

At first I thought that it might have something to do with the JTAG interface being enabled, but the problem still occurs after disabling it by setting the fuses.

this seems like a likely theory. Are you sure you have the fuse settings correct for disabled JTAG?

I´m a beginner, so I might have the fuses set wrongly to disable JTAG.

These are all settings:

atmega644.name=Sanguino W/ ATmega644P

atmega644.upload.protocol=stk500
atmega644.upload.maximum_size=63488
atmega644.upload.speed=57600

atmega644.bootloader.low_fuses=0xFF
atmega644.bootloader.high_fuses=0xD2
atmega644.bootloader.extended_fuses=0xFF
atmega644.bootloader.path=atmega
atmega644.bootloader.file=ATmegaBOOT_168_atmega644p.hex
#atmega644.bootloader.file=ATmegaBOOT_644P.hex
atmega644.bootloader.unlock_bits=0x3F
atmega644.bootloader.lock_bits=0x0F

atmega644.build.mcu=atmega644p
atmega644.build.f_cpu=16000000L
atmega644.build.core=arduino
atmega644.build.variant=standard
6

I changed the fuse settings:

atmega644.bootloader.low_fuses=0xFF
atmega644.bootloader.high_fuses=0xD2
atmega644.bootloader.extended_fuses=0xFD

Now I can use D18 and D19 for reading the dipswitch.

Thanks!