Analog Digital Umwandlung, einstiegs Code.

[julius (Gast)]

Hi,


habe hier ein ADC Beispiel das einfach nicht funktionieren will.

#include <avr/io.h> //Defines pins, ports, etc.
#include <util/delay.h>

static inline void initADC0(void) {
  ADMUX |= (1 << REFS0); //reference voltage on AVCC
  //ADCSRA |= (1 << ADPS1) | (1 << ADPS0); //ADC clock prescaler /8
    ADCSRA |= (1 << ADPS1) | (1 << ADPS2); //ADC clock prescaler /64

  ADCSRA |= (1 << ADEN); //enables the ADC
}

int main(void) {
  uint16_t potentiometerValue;
  uint16_t threshold_level;
  threshold_level= 0b10000000;
  DDRD |= (1 << PD7); //Data Direction Register B: writing a 1 to the bit enables output

  initADC0();

  while (1) {
    ADCSRA |= (1 << ADSC); //start ADC conversion
    loop_until_bit_is_clear(ADCSRA, ADSC); //wait until ADC conversion is done
    potentiometerValue= ADC; //read ADC value in
    if (potentiometerValue > threshold_level) {
      PORTD= 0b10000000; //turn on LED attached to port PB0
    }
    else {
      PORTD= 0b00000000; //turn off LED attached to port PB0
    }
      return (0); //this line is never actually reached
    }
}

Quelle: 
http://www.learningaboutelectronics.com/Articles/AVR-potentiometer-circuit.php
Leicht abgewandelt.

Verkabelung angepasst an Atmega32, ADC0 = PA0, led out = PD7


Laufen soll es auf einem Atmega32 mit 8Mhz und einem prescalar von 64 
für 125.000hz Abtastrate.
Eine LED ist an PD7 angeschlossen, soll an sein wenn der ADC0 über 128 
steht und aus darunter.
Momentan ist die LED immer an.


Was läuft hier falsch?



Zum kompilieren verwende ich diese Makefile:

# Hey Emacs, this is a -*- makefile -*-
#
# WinAVR makefile written by Eric B. Weddington, J�rg Wunsch, et al.
# Released to the Public Domain
# Please read the make user manual!
#
# Additional material for this makefile was submitted by:
#  Tim Henigan
#  Peter Fleury
#  Reiner Patommel
#  Sander Pool
#  Frederik Rouleau
#  Markus Pfaff
#
# On command line:
#
# make all = Make software.
#
# make clean = Clean out built project files.
#
# make coff = Convert ELF to AVR COFF (for use with AVR Studio 3.x or VMLAB).
#
# make extcoff = Convert ELF to AVR Extended COFF (for use with AVR Studio
#                4.07 or greater).
#
# make program = Download the hex file to the device, using avrdude.  Please
#                customize the avrdude settings below first!
#
# make filename.s = Just compile filename.c into the assembler code only
#
# To rebuild project do "make clean" then "make all".
#

# mth 2004/09 
# Differences from WinAVR 20040720 sample:
# - DEPFLAGS according to Eric Weddingtion's fix (avrfreaks/gcc-forum)
# - F_OSC Define in CFLAGS and AFLAGS


# MCU name
#MCU = atmega168
DEVICE = atmega32
MCU = $(DEVICE)

# Main Oscillator Frequency
# This is only used to define F_OSC in all assembler and c-sources.
F_OSC = 8000000
F_CPU = $(F_OSC)
CFLAGS = -mmcu=$(DEVICE) -DF_CPU=$(F_CPU)

# Output format. (can be srec, ihex, binary)
FORMAT = ihex

# Target file name (without extension).
TARGET = poti


# List C source files here. (C dependencies are automatically generated.)
SRC = $(TARGET).c


# List Assembler source files here.
# Make them always end in a capital .S.  Files ending in a lowercase .s
# will not be considered source files but generated files (assembler
# output from the compiler), and will be deleted upon "make clean"!
# Even though the DOS/Win* filesystem matches both .s and .S the same,
# it will preserve the spelling of the filenames, and gcc itself does
# care about how the name is spelled on its command-line.
ASRC = 



# Optimization level, can be [0, 1, 2, 3, s]. 
# 0 = turn off optimization. s = optimize for size.
# (Note: 3 is not always the best optimization level. See avr-libc FAQ.)
OPT = s

# Debugging format.
# Native formats for AVR-GCC's -g are stabs [default], or dwarf-2.
# AVR (extended) COFF requires stabs, plus an avr-objcopy run.
#DEBUG = stabs
DEBUG = dwarf-2

# List any extra directories to look for include files here.
#     Each directory must be seperated by a space.
EXTRAINCDIRS = 


# Compiler flag to set the C Standard level.
# c89   - "ANSI" C
# gnu89 - c89 plus GCC extensions
# c99   - ISO C99 standard (not yet fully implemented)
# gnu99 - c99 plus GCC extensions
CSTANDARD = -std=gnu99

# Place -D or -U options here
CDEFS =

# Place -I options here
CINCS =


# Compiler flags.
#  -g*:          generate debugging information
#  -O*:          optimization level
#  -f...:        tuning, see GCC manual and avr-libc documentation
#  -Wall...:     warning level
#  -Wa,...:      tell GCC to pass this to the assembler.
#    -adhlns...: create assembler listing
CFLAGS += -g$(DEBUG)
CFLAGS += $(CDEFS) $(CINCS)
CFLAGS += -O$(OPT)
CFLAGS += -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums
CFLAGS += -Wall -Wextra -Wstrict-prototypes
CFLAGS += -Wa,-adhlns=$(<:.c=.lst)
CFLAGS += $(patsubst %,-I%,$(EXTRAINCDIRS))
CFLAGS += $(CSTANDARD)
#CFLAGS += -DF_OSC=$(F_OSC)



# Assembler flags.
#  -Wa,...:   tell GCC to pass this to the assembler.
#  -ahlms:    create listing
#  -gstabs:   have the assembler create line number information; note that
#             for use in COFF files, additional information about filenames
#             and function names needs to be present in the assembler source
#             files -- see avr-libc docs [FIXME: not yet described there]
ASFLAGS = -Wa,-adhlns=$(<:.S=.lst),-gstabs 
ASFLAGS += -DF_OSC=$(F_OSC)


#Additional libraries.

# Minimalistic printf version
PRINTF_LIB_MIN = -Wl,-u,vfprintf -lprintf_min

# Floating point printf version (requires MATH_LIB = -lm below)
PRINTF_LIB_FLOAT = -Wl,-u,vfprintf -lprintf_flt

PRINTF_LIB = 

# Minimalistic scanf version
SCANF_LIB_MIN = -Wl,-u,vfscanf -lscanf_min

# Floating point + %[ scanf version (requires MATH_LIB = -lm below)
SCANF_LIB_FLOAT = -Wl,-u,vfscanf -lscanf_flt

SCANF_LIB = 

MATH_LIB = -lm

# External memory options

# 64 KB of external RAM, starting after internal RAM (ATmega128!),
# used for variables (.data/.bss) and heap (malloc()).
#EXTMEMOPTS = -Wl,-Tdata=0x801100,--defsym=__heap_end=0x80ffff

# 64 KB of external RAM, starting after internal RAM (ATmega128!),
# only used for heap (malloc()).
#EXTMEMOPTS = -Wl,--defsym=__heap_start=0x801100,--defsym=__heap_end=0x80ffff

EXTMEMOPTS =

# Linker flags.
#  -Wl,...:     tell GCC to pass this to linker.
#    -Map:      create map file
#    --cref:    add cross reference to  map file
LDFLAGS = -Wl,-Map=$(TARGET).map,--cref
LDFLAGS += $(EXTMEMOPTS)
LDFLAGS += $(PRINTF_LIB) $(SCANF_LIB) $(MATH_LIB)




# Programming support using avrdude. Settings and variables.

# Programming hardware: alf avr910 avrisp bascom bsd 
# dt006 pavr picoweb pony-stk200 sp12 stk200 stk500
#
# Type: avrdude -c ?
# to get a full listing.
#
AVRDUDE_PROGRAMMER = stk500

# com1 = serial port. Use lpt1 to connect to parallel port.
AVRDUDE_PORT = com1    # programmer connected to serial device

AVRDUDE_WRITE_FLASH = -U flash:w:$(TARGET).hex
#AVRDUDE_WRITE_EEPROM = -U eeprom:w:$(TARGET).eep


# Uncomment the following if you want avrdude's erase cycle counter.
# Note that this counter needs to be initialized first using -Yn,
# see avrdude manual.
#AVRDUDE_ERASE_COUNTER = -y

# Uncomment the following if you do /not/ wish a verification to be
# performed after programming the device.
#AVRDUDE_NO_VERIFY = -V

# Increase verbosity level.  Please use this when submitting bug
# reports about avrdude. See <http://savannah.nongnu.org/projects/avrdude> 
# to submit bug reports.
#AVRDUDE_VERBOSE = -v -v

AVRDUDE_FLAGS = -p $(MCU) -P $(AVRDUDE_PORT) -c $(AVRDUDE_PROGRAMMER)
AVRDUDE_FLAGS += $(AVRDUDE_NO_VERIFY)
AVRDUDE_FLAGS += $(AVRDUDE_VERBOSE)
AVRDUDE_FLAGS += $(AVRDUDE_ERASE_COUNTER)



# ---------------------------------------------------------------------------

# Define directories, if needed.
DIRAVR = c:/winavr
DIRAVRBIN = $(DIRAVR)/bin
DIRAVRUTILS = $(DIRAVR)/utils/bin
DIRINC = .
DIRLIB = $(DIRAVR)/avr/lib


# Define programs and commands.
SHELL = sh
CC = avr-gcc
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
SIZE = avr-size
NM = avr-nm
AVRDUDE = avrdude
REMOVE = rm -f
COPY = cp




# Define Messages
# English
MSG_ERRORS_NONE = Errors: none
MSG_BEGIN = -------- begin --------
MSG_END = --------  end  --------
MSG_SIZE_BEFORE = Size before: 
MSG_SIZE_AFTER = Size after:
MSG_COFF = Converting to AVR COFF:
MSG_EXTENDED_COFF = Converting to AVR Extended COFF:
MSG_FLASH = Creating load file for Flash:
MSG_EEPROM = Creating load file for EEPROM:
MSG_EXTENDED_LISTING = Creating Extended Listing:
MSG_SYMBOL_TABLE = Creating Symbol Table:
MSG_LINKING = Linking:
MSG_COMPILING = Compiling:
MSG_ASSEMBLING = Assembling:
MSG_CLEANING = Cleaning project:




# Define all object files.
OBJ = $(SRC:.c=.o) $(ASRC:.S=.o) 

# Define all listing files.
LST = $(ASRC:.S=.lst) $(SRC:.c=.lst)


# Compiler flags to generate dependency files.
### GENDEPFLAGS = -Wp,-M,-MP,-MT,$(*F).o,-MF,.dep/$(@F).d
GENDEPFLAGS = -MD -MP -MF .dep/$(@F).d

# Combine all necessary flags and optional flags.
# Add target processor to flags.
ALL_CFLAGS = -mmcu=$(MCU) -I. $(CFLAGS) $(GENDEPFLAGS)
ALL_ASFLAGS = -mmcu=$(MCU) -I. -x assembler-with-cpp $(ASFLAGS)





# Default target.
all: begin gccversion sizebefore build sizeafter finished end

build: elf hex eep lss sym

elf: $(TARGET).elf
hex: $(TARGET).hex
eep: $(TARGET).eep
lss: $(TARGET).lss 
sym: $(TARGET).sym



# Eye candy.
# AVR Studio 3.x does not check make's exit code but relies on
# the following magic strings to be generated by the compile job.
begin:
  @echo
  @echo $(MSG_BEGIN)

finished:
  @echo $(MSG_ERRORS_NONE)

end:
  @echo $(MSG_END)
  @echo


# Display size of file.
HEXSIZE = $(SIZE) --target=$(FORMAT) $(TARGET).hex
ELFSIZE = $(SIZE) -A $(TARGET).elf
sizebefore:
  @if [ -f $(TARGET).elf ]; then echo; echo $(MSG_SIZE_BEFORE); $(ELFSIZE); echo; fi

sizeafter:
  @if [ -f $(TARGET).elf ]; then echo; echo $(MSG_SIZE_AFTER); $(ELFSIZE); echo; fi



# Display compiler version information.
gccversion : 
  @$(CC) --version



# Program the device.  
program: $(TARGET).hex $(TARGET).eep
  $(AVRDUDE) $(AVRDUDE_FLAGS) $(AVRDUDE_WRITE_FLASH) $(AVRDUDE_WRITE_EEPROM)




# Convert ELF to COFF for use in debugging / simulating in AVR Studio or VMLAB.
COFFCONVERT=$(OBJCOPY) --debugging \
--change-section-address .data-0x800000 \
--change-section-address .bss-0x800000 \
--change-section-address .noinit-0x800000 \
--change-section-address .eeprom-0x810000 


coff: $(TARGET).elf
  @echo
  @echo $(MSG_COFF) $(TARGET).cof
  $(COFFCONVERT) -O coff-avr $< $(TARGET).cof


extcoff: $(TARGET).elf
  @echo
  @echo $(MSG_EXTENDED_COFF) $(TARGET).cof
  $(COFFCONVERT) -O coff-ext-avr $< $(TARGET).cof



# Create final output files (.hex, .eep) from ELF output file.
%.hex: %.elf
  @echo
  @echo $(MSG_FLASH) $@
  $(OBJCOPY) -O $(FORMAT) -R .eeprom $< $@

%.eep: %.elf
  @echo
  @echo $(MSG_EEPROM) $@
  -$(OBJCOPY) -j .eeprom --set-section-flags=.eeprom="alloc,load" \
  --change-section-lma .eeprom=0 -O $(FORMAT) $< $@

# Create extended listing file from ELF output file.
%.lss: %.elf
  @echo
  @echo $(MSG_EXTENDED_LISTING) $@
  $(OBJDUMP) -h -S $< > $@

# Create a symbol table from ELF output file.
%.sym: %.elf
  @echo
  @echo $(MSG_SYMBOL_TABLE) $@
  $(NM) -n $< > $@



# Link: create ELF output file from object files.
.SECONDARY : $(TARGET).elf
.PRECIOUS : $(OBJ)
%.elf: $(OBJ)
  @echo
  @echo $(MSG_LINKING) $@
  $(CC) $(ALL_CFLAGS) $(OBJ) --output $@ $(LDFLAGS)


# Compile: create object files from C source files.
%.o : %.c
  @echo
  @echo $(MSG_COMPILING) $<
  $(CC) -c $(ALL_CFLAGS) $< -o $@ 


# Compile: create assembler files from C source files.
%.s : %.c
  $(CC) -S $(ALL_CFLAGS) $< -o $@


# Assemble: create object files from assembler source files.
%.o : %.S
  @echo
  @echo $(MSG_ASSEMBLING) $<
  $(CC) -c $(ALL_ASFLAGS) $< -o $@



# Target: clean project.
clean: begin clean_list finished end

clean_list :
  @echo
  @echo $(MSG_CLEANING)
  $(REMOVE) $(TARGET).hex
  $(REMOVE) $(TARGET).eep
  $(REMOVE) $(TARGET).obj
  $(REMOVE) $(TARGET).cof
  $(REMOVE) $(TARGET).elf
  $(REMOVE) $(TARGET).map
  $(REMOVE) $(TARGET).obj
  $(REMOVE) $(TARGET).a90
  $(REMOVE) $(TARGET).sym
  $(REMOVE) $(TARGET).lnk
  $(REMOVE) $(TARGET).lss
  $(REMOVE) $(OBJ)
  $(REMOVE) $(LST)
  $(REMOVE) $(SRC:.c=.s)
  $(REMOVE) $(SRC:.c=.d)
  $(REMOVE) .dep/*



# Include the dependency files.
-include $(shell mkdir .dep 2>/dev/null) $(wildcard .dep/*)


# Listing of phony targets.
.PHONY : all begin finish end sizebefore sizeafter gccversion \
build elf hex eep lss sym coff extcoff \
clean clean_list program

[Tom (Gast)]

julius schrieb:
> return (0); //this line is never actually reached

Tip: Wo endet die while(1)-Schleife genau?

[Tom (Gast)]

Nachtrag:

> http://www.learningaboutelectronics.com/Articles/A

Wenn auf einer Seite nicht vernünftig formatierter Quellcode (und das 
Wort LM741) auftauchen, ist das als Warnung in Bezug auf inhaltliche 
Qualität zu verstehen.

[julius (Gast)]

Ok, der Code war jetzt nicht schön formatiert. An schlechten Code hatte 
ich nicht gleich dabei gedacht.

mit dem return(0) ausdokumentiert funktioniert der Code, halbwegs.
Der Bereich in dem die LED aus ist ist relativ klein, vielleicht ein 
viertel der Poti Drehung.

[julius (Gast)]

Was ist verkehrt am LM741?

[Andreas B. (bitverdreher)]

julius schrieb:
> An schlechten Code hatte
> ich nicht gleich dabei gedacht.

Das solltest Du aber.

> Was ist verkehrt am LM741?

R42 ist falsch beschaltet.

Gruß
Andreas

[Felix Adam (Gast)]

Du hast die Schwelle auf 128 festgelegt, während der Adc einen Wert bis 
1023 liefert. Womöglich deshalb?

[Forist (Gast)]

julius schrieb:
> Was läuft hier falsch?
>
> Zum kompilieren verwende ich diese Makefile:
> ...

Für Make-Files in der Länge gibt es die Funktion Anhang. Wer soll denn 
beim Lesen durch den ganzen Kram durchscrollen.

Erst Nachdenken ...

Viel wichtiger wäre zu wissen, ob z.B. loop_until_bit_is_clear() tut, 
was es soll und ob dein µC tatsächlich mit 8MHz läuft.

[Wolfgang (Gast)]

julius schrieb:
> return (0); //this line is never actually reached
>     }
> }

Und warum machst du dann hinter return(0) zwei geschweifte Klammern 
zu?

[Tom (Gast)]

julius schrieb:
> An schlechten Code hatte
> ich nicht gleich dabei gedacht.

Wer ernsthaft mit Quellcode arbeitet, würde nie unformatierten Quellcode 
irgendwohin klatschen, als Lehrbeispiel schon gar nicht. Mit 
formatiertem Code  sieht man mit minimaler Erfahrung das falsche return 
innerhalb der Endlos-Main-Schleife sofort.

Immerhin hast Du aus dem Beispiel gelernt, dass Kommentare völlig 
irreführend sein können ;)


julius schrieb:
> Was ist verkehrt am LM741?

Zu seiner Zeit nichts. Aber seit vielen vielen Jahren ist das einzige 
Problem, dessen Lösung 741 heißt, dieses: "Ich habe noch einen Haufen 
741 in der Bastelkiste und will die verbasteln." In allen anderen Fällen 
gibt es geeignetere OPVs. Wenn der 741 in einer Lehr-Seite auftaucht, 
heißt das mit großer Wahrscheinlichkeit, dass selbige mehr oder minder 
kompetent von irgendwo zusammenkopiert ist.