st52f513 STMicroelectronics, st52f513 Datasheet - Page 25

• Manufacturer Part Number: st52f513
• Description: 8-bit Microcontrollers
• Manufacturer: STMicroelectronics

Flash and EEPROM are programmed electrically
just applying the supply voltage and they are also
erased electrically; this feature allows the user to
easily reprogram the memory without taking the
device off from the board (In Situ Programming
ISP). Data and commands are transmitted through
the I
also be written run-time with the In Application
Programming (IAP)
NVM can be locked by the user during the
programming phase, in order to prevent external
operation such as reading the program code and
assuring protection of user intellectual property.
Flash and EEPROM pages can be protected by
unintentional writings.
The operations that can be performed on the NVM
during the Programming Phase, ISP and IAP are
described in detail in the
Figure 3.3 System and User Stack
2
C serial communication protocol. Data can
SYSTEM STACK
USER STACK
POINTER
POINTER
20FFh
20FEh
2001h
2000h
USER STACK LEVEL 4
USER STACK LEVEL 3
USER STACK LEVEL 2
USER STACK LEVEL 1
Section
SYSTEM STACK
SYSTEM STACK
SYSTEM STACK
SYSTEM STACK
RAM BENCH
USER DATA
LEVEL 1
LEVEL 2
LEVEL 3
LEVEL 4
4.
PUSH X
IRQ
3.4 System and User Stacks
The System and User Stacks are located in the
Program/Data memory in the RAM benches.
System Stacks are used to push the Program
Counter (PC) after an Interrupt Request or a
Subroutine Call. After a RET (Return from a
subroutine) or a RETI (Return from an interrupt)
the PC that is saved is popped from the stack and
restored. After an interrupt request, the flags are
also saved in a reserved stack inside the core, so
each interrupt has its own flags.
The System Stack is located in the last RAM bench
starting from the last address (20FFh) inside the
bench page. The System Stack Pointer (SSP) can
be read and modified by the user. For each level of
stack 2 bytes of the RAM are used. The SSP points
to the first currently available stack position. When
a subroutine call or interrupt request occurs, the
content of the PC is stored in a couple of locations
pointed to by the SSP that is decreased by 2.
POP X
RETI
CONFIGURATION REGISTERS
PROGRAM COUNTER
USER STACK TOP MSB
USER STACK TOP LSB
LOCATION ADRESS
ST52510xx ST52513xx
PAGE NUMBER
REGISTER FILE
REGISTER X
LSB
MSB
25/136