Memory

---

Detailed Description

The MCU ATmega128 has three different types of memory:

1. PROGMEM - program memory, flash technology, size 128KB
2. RAM - 4KB
3. EEPROM - 4KB

TODO see also protected memory, idle malloc

Some of the functions can access any of the memories.

Memory model

For developer following functions simplify the memory access:

• u8 rb(const void *addr) - read one byte from address addr.
• u16 rw(const void *addr) - read one word from address addr.
• void wb(void *addr, u8 val) - write one byte (=val) to address addr.
• void ww(void *addr, u16 val) - write one word (=val) to address addr.

For wb() and ww() only the RAM or EEPROM makes sence.

Memory allocation

For RAM allocation you can use the standard malloc(), free() calls and

 #include <stdlib.h> 

To access EEPROM you must use emalloc(), efree() calls.

On PROGMEM

To insert some data into PROGMEM in compilation time you can use the attribute PROGMEM. Example:

u8 PROGMEM data[]={0,1,2,3};

includes {0,1,2,3} into PROGMEM.

To access such data you must use rb() or rw() calls.

u8 PROGMEM data[]={0,1,2,3};
u8 x;
u8 i;

for(i=0;i<sizeof(data);i++) x=rb(data+i);

Attention:

Because or very little RAM we suggest to put everything possible into PROGMEM, esp. strings.

There is a very little stack so use malloc()/free() rather than local arrays.

For details on PROGMEM please refer to AVR LIBC documentation.

Shared Memory

It is possible to share memory between application, i.e. one application may have access to some data of another application.

Shared memory is implemented by key to pointer association, where key is for simplicity one byte number. First application prepares memory and uses u8 shmem_reg_key(u8 key, void *pointer) to associate key<->pointer. Another application makes lookup on given key and pointer is returned by void * shmem_key(u8 key).

Defines

• #define MEM_R
• #define MEM_P
• #define MEM_E
• #define MEM_D

Typedefs

• typedef unsigned char u8
• typedef unsigned short u16
• typedef unsigned long u32
• typedef char b8
• typedef short b16
• typedef long b32

Functions

• u8 rb (const void *addr)
• void wb (void *addr, u8 val)
• u16 rw (const void *addr)
• void ww (void *addr, u16 val)
• u8 get_bit (u8 *buf, u16 bit)
• void set_bit (u8 *buf, u16 bit, u8 val)
• u8 swap_nibble (u8 x)
• u8 * buf_A (void)
• u8 * buf_B (void)
• void * emalloc (u16 size)
• void efree (void *ptr)
• void reg_app_data (void *data)
• void * app_data (void)
• void _init (void)
• u8 shmem_reg_key (u8 key, void *pointer)
• void * shmem_key (u8 key)

---

Define Documentation

#define MEM_D

Indicates memory card.

#define MEM_E

Indicates EEPROM.

#define MEM_P

Indicates PROGMEM (flash memory).

#define MEM_R

Indicates RAM.

---

Typedef Documentation

typedef short b16

signed 2bytes=16bits

typedef long b32

signed 4bytes=32bits

typedef char b8

signed 1byte=8bits

typedef unsigned short u16

unsigned 2bytes=16bits

typedef unsigned long u32

unsigned 4bytes=32bits

typedef unsigned char u8

unsigned 1byte=8bits

---

Function Documentation

void _init (  void   )

Copy data from PROGMEM to RAM and clear BSS.

void* app_data (  void   )

Return pointer on application persistent data. Examples: certs.c, and fake_sim.c.

u8* buf_A (  void   )

STK thread buffer. In this buffer STK command is composed, waits for FETCH and TERMINAL RESPONSE is stored. Attention: Can be used only in stk_thread(). Examples: braled.c, braping.c, certs.c, mc.c, and stkcmd.c.

u8* buf_B (  void   )

General GSM buffer. All the ME<->TURBO<->SIM communication happens here. Attention: Can be modified only in stk_thread() and its content is not valid after STK command. Examples: adc.c, braping.c, calc.c, certs.c, fake_sim.c, mc.c, net.c, shmem.c, sysinfo.c, temperature.c, test_idle.c, and test_prot_mem.c.

void efree (  void *  ptr  )

Free emalloc'ed chunk. Parameters: ptr  Examples: certs.c, fake_sim.c, and tsmsacl.c.

void* emalloc (  u16  size  )

Same as malloc but in EEPROM. Parameters: size  Examples: certs.c, fake_sim.c, and tsmsacl.c.

u8 get_bit (  u8 *  buf, u16  bit )

Return value of bit in the array. Parameters: buf  pointer on byte array (RAM only) bit  Returns: 0 or 1. See also: set_bit()

u8 rb (  const void *  addr  )

Read byte from memory. Parameters: addr  EEPROM, PROGMEM, RAM memory address Examples: certs.c, fake_sim.c, and tsmsacl.c.

void reg_app_data (  void *  data  )

Store (in EEPROM) pointer on application persistent data. Parameters: data  Examples: certs.c, and fake_sim.c.

u16 rw (  const void *  addr  )

Read word from memory. Parameters: addr  EEPROM, PROGMEM, RAM memory address Examples: certs.c, fake_sim.c, hello_world_ucs2.c, and tsmsacl.c.

void set_bit (  u8 *  buf, u16  bit, u8  val )

Set bit in the array. Parameters: buf  pointer on byte array (RAM only) bit  val  0 or 1 See also: get_bit()

void* shmem_key (  u8  key  )

Find pointer associated with key. Parameters: key  look for given key Returns: pointer or NULL Examples: shmem.c.

u8 shmem_reg_key (  u8  key, void *  pointer )

Register shared memory key - used for finding/denoting shared memory between application. Parameters: key  number/byte denoting the shared memory pointer  store pointer to be associated with key Returns: NO_ERROR or ERR_UNKNOWN if cannot be created Examples: shmem.c.

u8 swap_nibble (  u8  x  )

Swap half-bytes, e.g. 0x10 = swap_nibble(0x01), Parameters: x

void wb (  void *  addr, u8  val )

Write byte to memory. Parameters: addr  EEPROM, RAM memory address val  value Examples: certs.c, fake_sim.c, and tsmsacl.c.

void ww (  void *  addr, u16  val )

Write word to memory. Parameters: addr  EEPROM, RAM memory address val  value. Examples: certs.c, fake_sim.c, and tsmsacl.c.