o add sram poc test

poc/sram_m32/1

@@ -0,0 +1,110 @@
+ 
+#include <avr/io.h>  
+#include <util/delay.h>
+#include <avr/eeprom.h> 
+
+#include <stdio.h>
+
+#include "uart.h"
+
+extern FILE uart_stdout;
+
+uint16_t ee_data01 __attribute__((section(".eeprom"))) = 0x01;
+uint16_t ee_data02 __attribute__((section(".eeprom"))) = 0x02;
+uint16_t ee_data03 __attribute__((section(".eeprom"))) = 0x03;
+uint16_t ee_data04 __attribute__((section(".eeprom"))) = 0x04;
+
+
+#define DATAPORT    PORTA
+#define ADDRPORTLO  PORTA
+#define ADDRPORTHI  PORTC
+#define CRTLPORT    PORTD
+
+
+#define LATCH_LE_PIN    2
+#define LATCH_OE_PIN    3
+#define SRAM_OE_PIN     4
+#define SRAM_CE_PIN     5
+#define SRAM_WE_PIN     6
+
+
+// LE high -> forward imput 
+// LE low  -> latch input
+#define LATCH_LEHI      CRTLPORT != _BV(LATCH_LE_PIN);     
+#define LATCH_LELO      CRTLPORT &=~_BV(LATCH_LE_PIN);
+// OE high -> normal logic level
+// OE low  -> high impendance
+#define LATCH_OEHI      CRTLPORT != _BV(LATCH_OE_PIN);
+#define LATCH_OELO      CRTLPORT &=~_BV(LATCH_OE_PIN);
+// OE high output disable
+// OE low output enable
+#define SRAM_OEHI       CRTLPORT != _BV(SRAM_OE_PIN);
+#define SRAM_OELO       CRTLPORT &=~_BV(SRAM_OE_PIN);
+// CE high chip disable
+// CE low chip enable
+#define SRAM_CEHI       CRTLPORT != _BV(SRAM_CE_PIN);
+#define SRAM_CELO       CRTLPORT &=~_BV(SRAM_CE_PIN);
+// WE high write disable
+// WE low write enable
+#define SRAM_WEHI       CRTLPORT != _BV(SRAM_WE_PIN);
+#define SRAM_WELO       CRTLPORT &=~_BV(SRAM_WE_PIN);
+
+
+
+
+int sram_write(uint16_t addr, uint8_t data)
+{
+
+    uint8_t addr_lo = addr &  8;
+    uint8_t addr_hi = addr >> 8;
+    
+    SRAM_OEHI;
+    SRAM_CELO;
+    SRAM_WELO;
+
+
+    DATAPORT = data;
+    
+    LATCH_LEHI
+    ADDRPORTLO = addr_lo;
+    ADDRPORTHI = addr_hi;
+    LATCH_LELO
+
+    SRAM_CEHI;
+
+    SRAM_CELO;
+
+
+}
+
+
+
+int main (void) {            // (2)
+ 
+    DDRB  = 0xff;             // (3)
+    PORTB = 0xff;             // (4)
+    uint8_t i = 0; 
+    uint8_t j = 7; 
+    uint8_t * addr = 0x0000;  
+    uint16_t c = 0; 
+    uart_init();
+    stdout = &uart_stdout;
+    
+    while(1) {                // (5a)
+        PORTB  |=  (1<< j);
+        j++;
+        if ( j == 8 ) j = 0; 
+        PORTB  &= ~(1 << j );  // Toggle PB0 z.B. angeschlossene LED
+        /* 
+           Die maximale Zeit pro Funktionsaufruf ist begrenzt auf 
+           262.14 ms / F_CPU in MHz (im Beispiel: 
+           262.1 / 3.6864 = max. 71 ms) 
+           16 * 62.5ms (+ Zeit für Schleife) = ca. eine Sekunde warten
+        */
+        
+        for (i=1; i<=70; i++)         
+            _delay_ms(15);    
+    }
+    return 0;                 // (6)
+}
+

poc/sram_m32/Makefile

@@ -0,0 +1,446 @@
+# Hey Emacs, this is a -*- makefile -*-
+#
+# WinAVR makefile written by Eric B. Weddington, Jörg 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 = atmega32
+
+# Main Oscillator Frequency
+# This is only used to define F_OSC in all assembler and c-sources.
+#F_OSC  = 3686400
+F_OSC  = 16000000
+
+# Output format. (can be srec, ihex, binary)
+FORMAT = ihex
+
+# Target file name (without extension).
+TARGET = main
+
+
+# List C source files here. (C dependencies are automatically generated.)
+SRC = $(TARGET).c uart.c fifo.c
+
+
+# List Assembler source files here.
+# Make them always end in a capital .S.  Files ending in a lowercase .s
+# will not be considered source files but generated files (assembler
+# output from the compiler), and will be deleted upon "make clean"!
+# Even though the DOS/Win* filesystem matches both .s and .S the same,
+# it will preserve the spelling of the filenames, and gcc itself does
+# care about how the name is spelled on its command-line.
+ASRC = 
+
+
+
+# Optimization level, can be [0, 1, 2, 3, s]. 
+# 0 = turn off optimization. s = optimize for size.
+# (Note: 3 is not always the best optimization level. See avr-libc FAQ.)
+OPT = s
+
+# Debugging format.
+# Native formats for AVR-GCC's -g are stabs [default], or dwarf-2.
+# AVR (extended) COFF requires stabs, plus an avr-objcopy run.
+#DEBUG = stabs
+#DEBUG = dwarf-2
+
+# List any extra directories to look for include files here.
+#     Each directory must be seperated by a space.
+EXTRAINCDIRS = 
+
+
+# Compiler flag to set the C Standard level.
+# c89   - "ANSI" C
+# gnu89 - c89 plus GCC extensions
+# c99   - ISO C99 standard (not yet fully implemented)
+# gnu99 - c99 plus GCC extensions
+CSTANDARD = -std=gnu99
+
+# Place -D or -U options here
+CDEFS =
+
+# Place -I options here
+CINCS =
+
+
+# Compiler flags.
+#  -g*:          generate debugging information
+#  -O*:          optimization level
+#  -f...:        tuning, see GCC manual and avr-libc documentation
+#  -Wall...:     warning level
+#  -Wa,...:      tell GCC to pass this to the assembler.
+#    -adhlns...: create assembler listing
+CFLAGS = -g$(DEBUG)
+CFLAGS += $(CDEFS) $(CINCS)
+CFLAGS += -O$(OPT)
+CFLAGS += -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums
+CFLAGS += -Wall -Wstrict-prototypes
+CFLAGS += -Wa,-adhlns=$(<:.c=.lst)
+CFLAGS += $(patsubst %,-I%,$(EXTRAINCDIRS))
+CFLAGS += $(CSTANDARD)
+CFLAGS += -DF_OSC=$(F_OSC) -DF_CPU=$(F_OSC)UL
+
+
+
+# Assembler flags.
+#  -Wa,...:   tell GCC to pass this to the assembler.
+#  -ahlms:    create listing
+#  -gstabs:   have the assembler create line number information; note that
+#             for use in COFF files, additional information about filenames
+#             and function names needs to be present in the assembler source
+#             files -- see avr-libc docs [FIXME: not yet described there]
+ASFLAGS = -Wa,-adhlns=$(<:.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) $(MATH_LIB)
+
+
+
+
+# Programming support using avrdude. Settings and variables.
+
+# Programming hardware: alf avr910 avrisp bascom bsd 
+# dt006 pavr picoweb pony-stk200 sp12 stk200 stk500
+#
+# Type: avrdude -c ?
+# to get a full listing.
+#
+AVRDUDE_PROGRAMMER = stk500v2
+
+# com1 = serial port. Use lpt1 to connect to parallel port.
+AVRDUDE_PORT = /dev/ttyUSB0    # programmer connected to serial device
+
+AVRDUDE_WRITE_FLASH = -U flash:w:$(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)
+
+# set 4mhz
+# avrdude -p atmega8 -P /dev/ttyUSB0  -c stk500v2 -U lfuse:w:0xe3:m 
+#
+
+# ---------------------------------------------------------------------------
+
+# 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. : 
+flash: $(TARGET).hex $(TARGET).eep
+	sudo $(AVRDUDE) $(AVRDUDE_FLAGS) $(AVRDUDE_WRITE_FLASH) $(AVRDUDE_WRITE_EEPROM)
+
+fuse_4_int:
+	sudo $(AVRDUDE) $(AVRDUDE_FLAGS)  -U lfuse:w:0xd3:m -U hfuse:w:0x99:m 
+
+fuse_16_ext:
+	sudo $(AVRDUDE) $(AVRDUDE_FLAGS)  -U lfuse:w:0xdf:m -U hfuse:w:0x99:m 
+
+
+
+
+
+# Convert ELF to COFF for use in debugging / simulating in AVR Studio or VMLAB.
+COFFCONVERT=$(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
+

poc/sram_m32/docs/sram_access.txt

@@ -0,0 +1,61 @@
+Zustand 1 :
+  OE des RAMS auf 1
+  CE   "  "   auf 0
+  WE   "  "   auf 0
+  Datenbus mit Datenwort besetzen
+  Adressbus setzen
+  Zustand = 2
+
+Zustand 2 :
+  CE des RAMS auf 1
+  Zustand = 3
+
+Zustand 3:
+  CE des RAMS auf 0
+  Datenbus hochohmig (also Z) setzen
+  Zustand = 0 (idle)
+
+Beim Lesen passiert folgendes
+
+Zustand 1 :
+  OE des RAMS auf 0
+  CE   "  "   auf 0
+  WE   "  "   auf 1
+  Datenbus hochohmig (also Z) setzen
+  Adressbus setzen
+  Zustand = 2
+
+Zustand 2 :
+  CE des RAMS auf 1
+  Zustand = 3
+
+Zustand 3:
+  CE des RAMS auf 0
+  Datenwort am Datenbus einlesen
+  Zustand = 0 (idle)
+
+
+
+
+
+
+
+
+
+
+OE/ und WR/ dürfen nicht gleichzeitig aktiv sein. Du mußt also bei
+ansteuern.
+
+Der Ablauf zum Beschreiben:
+1. OE/ und WR/ inaktiv
+2. Adresse anlegen
+3. Daten anlegen
+4. WR/ aktiv
+5. WR/ inaktiv
+
+Der Ablauf zum Lesen:
+1. OE/ und WR/ inaktiv
+2. Adresse anlegen
+3. OE/ aktiv
+4. Daten einlesen
+5. OE/ inaktiv

poc/sram_m32/fifo.c

@@ -0,0 +1,28 @@
+#include "fifo.h"
+
+void fifo_init(fifo_t * f, uint8_t * buffer, const uint8_t size)
+{
+    f->count = 0;
+    f->pread = f->pwrite = buffer;
+    f->read2end = f->write2end = f->size = size;
+}
+
+uint8_t fifo_put(fifo_t * f, const uint8_t data)
+{
+    return _inline_fifo_put(f, data);
+}
+
+uint8_t fifo_get_wait(fifo_t * f)
+{
+    while (!f->count);
+
+    return _inline_fifo_get(f);
+}
+
+int fifo_get_nowait(fifo_t * f)
+{
+    if (!f->count)
+        return -1;
+
+    return (int) _inline_fifo_get(f);
+}

poc/sram_m32/fifo.h

@@ -0,0 +1,69 @@
+#ifndef _FIFO_H_
+#define _FIFO_H_
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+typedef struct {
+    uint8_t volatile count;     // # Zeichen im Puffer
+    uint8_t size;               // Puffer-Größe
+    uint8_t *pread;             // Lesezeiger
+    uint8_t *pwrite;            // Schreibzeiger
+    uint8_t read2end, write2end;        // # Zeichen bis zum Überlauf Lese-/Schreibzeiger
+} fifo_t;
+
+extern void fifo_init(fifo_t *, uint8_t * buf, const uint8_t size);
+extern uint8_t fifo_put(fifo_t *, const uint8_t data);
+extern uint8_t fifo_get_wait(fifo_t *);
+extern int fifo_get_nowait(fifo_t *);
+
+static inline uint8_t _inline_fifo_put(fifo_t * f, const uint8_t data)
+{
+    if (f->count >= f->size)
+        return 0;
+
+    uint8_t *pwrite = f->pwrite;
+
+    *(pwrite++) = data;
+
+    uint8_t write2end = f->write2end;
+
+    if (--write2end == 0) {
+        write2end = f->size;
+        pwrite -= write2end;
+    }
+
+    f->write2end = write2end;
+    f->pwrite = pwrite;
+
+    uint8_t sreg = SREG;
+    cli();
+    f->count++;
+    SREG = sreg;
+
+    return 1;
+}
+
+static inline uint8_t _inline_fifo_get(fifo_t * f)
+{
+    uint8_t *pread = f->pread;
+    uint8_t data = *(pread++);
+    uint8_t read2end = f->read2end;
+
+    if (--read2end == 0) {
+        read2end = f->size;
+        pread -= read2end;
+    }
+
+    f->pread = pread;
+    f->read2end = read2end;
+
+    uint8_t sreg = SREG;
+    cli();
+    f->count--;
+    SREG = sreg;
+
+    return data;
+}
+
+#endif                          /* _FIFO_H_ */

poc/sram_m32/main.c

@@ -0,0 +1,140 @@
+ 
+#include <avr/io.h>  
+#include <util/delay.h>
+#include <avr/eeprom.h> 
+
+#include <stdio.h>
+
+#include "uart.h"
+
+
+#define debug(x, fmt) printf("%s:%u: %s=" fmt, __FILE__, __LINE__, #x, x)
+
+extern FILE uart_stdout;
+
+uint16_t ee_data01 __attribute__((section(".eeprom"))) = 0x01;
+uint16_t ee_data02 __attribute__((section(".eeprom"))) = 0x02;
+uint16_t ee_data03 __attribute__((section(".eeprom"))) = 0x03;
+uint16_t ee_data04 __attribute__((section(".eeprom"))) = 0x04;
+
+
+#define DATAPORT    PORTA
+#define ADDRPORTLO  PORTA
+#define ADDRPORTHI  PORTC
+#define CRTLPORT    PORTD
+
+
+#define LATCH_LE_PIN    2
+#define LATCH_OE_PIN    3
+#define SRAM_OE_PIN     4
+#define SRAM_CE_PIN     5
+#define SRAM_WE_PIN     6
+
+
+// LE high -> forward imput 
+// LE low  -> latch input
+#define LATCH_LEHI      CRTLPORT != _BV(LATCH_LE_PIN);     
+#define LATCH_LELO      CRTLPORT &=~_BV(LATCH_LE_PIN);
+// OE high -> normal logic level
+// OE low  -> high impendance
+#define LATCH_OEHI      CRTLPORT != _BV(LATCH_OE_PIN);
+#define LATCH_OELO      CRTLPORT &=~_BV(LATCH_OE_PIN);
+// OE high output disable
+// OE low output enable
+#define SRAM_OEHI       CRTLPORT != _BV(SRAM_OE_PIN);
+#define SRAM_OELO       CRTLPORT &=~_BV(SRAM_OE_PIN);
+// CE high chip disable
+// CE low chip enable
+#define SRAM_CEHI       CRTLPORT != _BV(SRAM_CE_PIN);
+#define SRAM_CELO       CRTLPORT &=~_BV(SRAM_CE_PIN);
+// WE high write disable
+// WE low write enable
+#define SRAM_WEHI       CRTLPORT != _BV(SRAM_WE_PIN);
+#define SRAM_WELO       CRTLPORT &=~_BV(SRAM_WE_PIN);
+
+
+
+
+int sram_write(uint16_t addr, uint8_t data)
+{
+
+    uint8_t addr_lo = addr &  8;
+    uint8_t addr_hi = addr >> 8;
+    
+    SRAM_OEHI;
+    SRAM_CELO;
+    SRAM_WELO;
+
+    LATCH_OEHI; 
+    LATCH_LEHI
+    DATAPORT = data;
+    LATCH_LELO
+
+    ADDRPORTLO = addr_lo;
+    ADDRPORTHI = addr_hi;
+
+    SRAM_CEHI;
+    
+    SRAM_CELO;
+
+    return 0;
+}
+
+
+int sram_read(uint16_t addr, uint8_t * data)
+{
+
+    uint8_t addr_lo = addr &  8;
+    uint8_t addr_hi = addr >> 8;
+    
+    SRAM_OELO;
+    SRAM_CELO;
+    SRAM_WEHI;
+
+    
+    LATCH_OEHI;
+    LATCH_LELO;
+
+    ADDRPORTLO = addr_lo;
+    ADDRPORTHI = addr_hi;
+
+    SRAM_CEHI;
+    
+    SRAM_CELO;
+
+    LATCH_LEHI;
+    *data = DATAPORT;
+
+    SRAM_OEHI;
+    return 0;
+}
+
+
+
+int main (void) {            // (2)
+ 
+    DDRB  = 0xff;             // (3)
+    PORTB = 0xff;             // (4)
+    uint8_t i = 0; 
+    uint8_t j = 7; 
+    uart_init();
+    stdout = &uart_stdout;
+    
+    while(1) {                // (5a)
+        PORTB  |=  (1<< j);
+        j++;
+        if ( j == 8 ) j = 0; 
+        PORTB  &= ~(1 << j );  // Toggle PB0 z.B. angeschlossene LED
+        /* 
+           Die maximale Zeit pro Funktionsaufruf ist begrenzt auf 
+           262.14 ms / F_CPU in MHz (im Beispiel: 
+           262.1 / 3.6864 = max. 71 ms) 
+           16 * 62.5ms (+ Zeit für Schleife) = ca. eine Sekunde warten
+        */
+        debug(j,"%x \n"); 
+        for (i=1; i<=70; i++)         
+            _delay_ms(15);    
+    }
+    return 0;                 // (6)
+}
+

poc/sram_m32/uart.c

@@ -0,0 +1,79 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+#include <stdio.h>
+#include "uart.h"
+#include "fifo.h"
+
+volatile struct
+{
+    uint8_t tmr_int: 1;
+    uint8_t adc_int: 1;
+    uint8_t rx_int: 1;
+}
+intflags;
+
+/*
+ *  * Last character read from the UART.
+ *   
+ */
+volatile char rxbuff;
+
+
+FILE uart_stdout = FDEV_SETUP_STREAM(uart_stream, NULL, _FDEV_SETUP_WRITE);
+
+void uart_init(void)
+{
+    UCSRA = _BV(U2X);     /* improves baud rate error @ F_CPU = 1 MHz */
+    UCSRB = _BV(TXEN)|_BV(RXEN)|_BV(RXCIE); /* tx/rx enable, rx complete intr */
+    UBRRL = (F_CPU / (8 * 115200UL)) - 1;  /* 9600 Bd */
+
+}
+
+
+ISR(USART_RXC_vect)
+{
+    uint8_t c;
+    c = UDR;
+    if (bit_is_clear(UCSRA, FE)){
+        rxbuff = c;
+        intflags.rx_int = 1;
+    }
+}
+
+
+void  uart_putc(uint8_t c)
+{
+    loop_until_bit_is_set(UCSRA, UDRE);
+    UDR = c;
+}
+
+
+void uart_puts(const char *s)
+{
+    do {
+        uart_putc(*s);
+    }
+    while (*s++);
+}
+
+void uart_puts_P(PGM_P s)
+{
+    while (1) {
+        unsigned char c = pgm_read_byte(s);
+        s++;
+        if ('\0' == c)
+            break;
+        uart_putc(c);
+    }
+}
+
+static int uart_stream(char c, FILE *stream)
+{
+    if (c == '\n')
+        uart_putc('\r');
+    loop_until_bit_is_set(UCSRA, UDRE);
+    UDR = c;
+    return 0;
+}
+

poc/sram_m32/uart.h

@@ -0,0 +1,18 @@
+#ifndef _UART_H_
+#define _UART_H_
+
+#define CR "\r\n"
+
+
+#include <avr/io.h>
+#include <avr/pgmspace.h>
+#include <stdio.h>
+
+void uart_init(void);
+void uart_putc(const uint8_t);
+void uart_puts(const char *s);
+void uart_puts_P(PGM_P s);
+static int uart_stream(char c, FILE *stream);
+
+
+#endif                          /* _UART_H_ */