I have a project that I created that used an SD Card Module. I have another project that will have it's own Micro Controller. Is it possible for the 2 projects to share the same SD Card Module. If so am I correct that both micro controllers SCK, MISO, & MOSI would all be connected to the same pin, but for the CS pin would does it matter what pin they use say 10, & 4?

Thanks
Scott 

Then he still has to code for ever combination of all possible combinations. Doesn't he?

How are you expecting the value to change?

I'm sure thats true, but he said "returns what button was pressed" not buttons were pressed.

You don't need 255.  If you do it the smart way you only need 8.

Which is what I have, you have to test with if then else logic anyways.

Can you just do something like this

switch (byte) {
case 10000000:
   ....
   ....
   break;
case 1000000:
   ....
   ....
   break;
case 100000:
   ....
   ....
   break;
case 10000:
   ....
   ....
   break;
case 1000:
   ....
   ....
   break;
case 100:
   ....
   ....
   break;
case 10:
   ....
   ....
   break;
case 1:
   ....
   ....
   break;
default:
   ....
   ....
   break;
}

I think what you are trying to do would require an interrupt. you appear to want to run a loop and display a value and then if that value changes it would be displaying the new value. I could be wrong but I too am still learning the Arduino. you will have to have the variable you want to display define as a global as volitile so that the interrup function could change the value. My understanding is that when am interrupt is called all control does to the interrupt function and all current processing stops until the interrupt function is completed, at which time the process continues. Hopes this helps.

Bumping this back to the top, still looking for an answer.

I am using timer interrupts, and I have a question when to you issue noInterrupts() does this stop the count flags or do the count flag or do they keep getting incremented and reset  or does all that stop.

All,

I am compiling 2boots on ubuntu and am getting the following warning? Also if I am understanding the instructions right PD4 is digital pin 4 for the Chipselect. To use the SD Card Module on the Uno its Digital Pin 10. When I change the pin from PD4 to PD10 i get errors. but first I'm just trying the get it to compile and upload. When I try to upload the PD4 the flash.sh throws errors but it will upload the nommc one correctly. anyways here is the warnings. is this something I should be concerned about?

scott@ubuntu:~/embedded-master/avr/2boots$ make
[ -d build ] || mkdir build

----------[2boots-atmega328p-16000000L-nommc-board-arduino.hex]-------------------
Compiling 2boots for:
- board-arduino
- MCU:atmega328p @ 16000kHz
- MMC: nommc

avr-gcc -g -Wall -Os -funsigned-char -fno-split-wide-types -fno-inline-small-functions -mcall-prologues -ffunction-sections -fdata-sections -ffreestanding -combine -fwhole-program -fno-jump-tables -mmcu=atmega328p -DF_CPU=16000000L    -Wl,--section-start=.text=0x7800  -Wl,--relax -nostartfiles -Wl,-gc-sections board-arduino.c mmc_fat.c stk500v1.c prog_flash.c -o build/2boots-arduino-atmega328p-16000000L-nommc.elf
board-arduino.c: In function ‘main’:
board-arduino.c:62:45: warning: function with qualified void return type called
stk500v1.c: In function ‘handle_addr’:
stk500v1.c:236:3: warning: dereferencing type-punned pointer will break strict-aliasing rules

sucessfully compiled to build/2boots-arduino-atmega328p-16000000L-nommc.elf
   text      data       bss       dec       hex   filename
    832         0       135       967       3c7   build/2boots-arduino-atmega328p-16000000L-nommc.elf
avr-objcopy -j .text -j .data -O ihex build/2boots-arduino-atmega328p-16000000L-nommc.elf build/2boots-arduino-atmega328p-16000000L-nommc.hex   


----------[2boots-atmega328p-16000000L-PD4-board-arduino.hex]-------------------
Compiling 2boots for:
- board-arduino
- MCU:atmega328p @ 16000kHz
- MMC: PD4

avr-gcc -g -Wall -Os -funsigned-char -fno-split-wide-types -fno-inline-small-functions -mcall-prologues -ffunction-sections -fdata-sections -ffreestanding -combine -fwhole-program -fno-jump-tables -mmcu=atmega328p -DF_CPU=16000000L  -DMMC_CS=PD4 -DMMC_PORT=PORTD -DMMC_DDR=DDRD  -Wl,--section-start=.text=0x7800  -Wl,--relax -nostartfiles -Wl,-gc-sections board-arduino.c mmc_fat.c stk500v1.c prog_flash.c -o build/2boots-arduino-atmega328p-16000000L-PD4.elf
board-arduino.c: In function ‘main’:
board-arduino.c:62:45: warning: function with qualified void return type called
stk500v1.c: In function ‘handle_addr’:
stk500v1.c:236:3: warning: dereferencing type-punned pointer will break strict-aliasing rules

sucessfully compiled to build/2boots-arduino-atmega328p-16000000L-PD4.elf
   text      data       bss       dec       hex   filename
   2184         0       674      2858       b2a   build/2boots-arduino-atmega328p-16000000L-PD4.elf
avr-objcopy -j .text -j .data -O ihex build/2boots-arduino-atmega328p-16000000L-PD4.elf build/2boots-arduino-atmega328p-16000000L-PD4.hex   

-----[Size reports]----------------------------------------

   text      data       bss       dec       hex   filename
      0      2184         0      2184       888   build/2boots-arduino-atmega328p-16000000L-PD4.hex
      0       832         0       832       340   build/2boots-arduino-atmega328p-16000000L-nommc.hex


Thanks for your help.

Does anyone know if this ebay item can be used to burn the bootloader and sketches to a standalone arduino. If so does anyone have any hookup diagrams?

http://www.ebay.com/itm/USBASP-USB-AVR-Programmer-for-Atmel-USB-ASP-USBISP-ISP-Arduino-Bootloader-USA-/150739530304?pt=LH_DefaultDomain_0&hash=item2318c6b240

Thanks
Scott

Sorry for that Actual file size. Also can the hex file be copied to windows in binary and use the Arduino IDE to burn to a board where the programmer is an Arduino as ISP unsing ladyada technique to load boot loader to a 328 chip with an arduino.

? All,

when I run the make on ubuntu it generates the following files. my question is; does the size of the hex file matter?

ls -la build/*.hex
-rw-rw-r-- 1 scott scott 2374 Feb  3 15:39 build/2boots-arduino-atmega168-16000000L-nommc.hex
-rw-rw-r-- 1 scott scott 6183 Feb  3 15:39 build/2boots-arduino-atmega168-16000000L-PD4.hex
-rw-rw-r-- 1 scott scott 2374 Feb  3 15:39 build/2boots-arduino-atmega168-8000000L-nommc.hex
-rw-rw-r-- 1 scott scott 6183 Feb  3 15:39 build/2boots-arduino-atmega168-8000000L-PD4.hex
-rw-rw-r-- 1 scott scott 2374 Feb  3 15:39 build/2boots-arduino-atmega328p-16000000L-nommc.hex
-rw-rw-r-- 1 scott scott 6183 Feb  3 15:39 build/2boots-arduino-atmega328p-16000000L-PD4.hex
-rw-rw-r-- 1 scott scott 2399 Feb  3 15:39 build/2boots-arduino-atmega328p-8000000L-nommc.hex
-rw-rw-r-- 1 scott scott 6195 Feb  3 15:39 build/2boots-arduino-atmega328p-8000000L-PD4.hex