SAF-C161U-LF V1.3 Infineon Technologies, SAF-C161U-LF V1.3 Datasheet - Page 403

• Manufacturer Part Number: SAF-C161U-LF V1.3
• Description: IC MCU ISDN 16BIT TTL TQFP-100
• Manufacturer: Infineon Technologies
• Series: C16xxr

Specifications of SAF-C161U-LF V1.3

• Core Processor: C166
• Core Size: 16-Bit
• Speed: 36MHz
• Connectivity: EBI/EMI, SPI, UART/USART, USB
• Peripherals: POR, PWM, WDT
• Number Of I /o: 56
• Program Memory Type: ROMless
• Ram Size: 3K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LFQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -
• Other names: SAFC161ULFV1.3X; SAFC161ULFV13XP; SP000007502

internal stack, this circular stack mechanism only requires to move that portion of stack
data which is really to be re-used (ie. the upper part of the defined stack area) instead of
the whole stack area. Stack data that remain in the lower part of the internal stack need
not be moved by the distance of the space being flushed or filled, as the stack pointer
automatically wraps around to the beginning of the freed part of the stack area.
Note: This circular stack technique is applicable for stack sizes of 32 to 512 words
When a boundary is reached, the stack underflow or overflow trap is entered, where the
user moves a predetermined portion of the internal stack to or from the external stack.
The amount of data transferred is determined by the average stack space required by
routines and the frequency of calls, traps, interrupts and returns. In most cases this will
be approximately one quarter to one tenth the size of the internal stack. Once the transfer
is complete, the boundary pointers are updated to reflect the newly allocated space on
the internal stack. Thus, the user is free to write code without concern for the internal
stack limits. Only the execution time required by the trap routines affects user programs.
The following procedure initializes the controller for usage of the circular stack
mechanism:
• Specify the size of the physical system stack area within the internal RAM (bitfield
• Define two pointers, which specify the upper and lower boundary of the external stack.
• Set the stack overflow pointer (STKOV) to the limit of the defined internal stack area
The internal stack will now fill until the overflow pointer is reached. After entry into the
overflow trap procedure, the top of the stack will be copied to the external memory. The
internal pointers will then be modified to reflect the newly allocated space. After exiting
from the trap procedure, the internal stack will wrap around to the top of the internal
stack, and continue to grow until the new value of the stack overflow pointer is reached.
When the underflow pointer is reached while the stack is meptied the bottom of stack is
reloaded from the external memory and the internal pointers are adjusted accordingly.
Linear Stack
C161U also offers a linear stack option (STKSZ = ‘111
use the complete internal RAM area. This provides a large system stack without
requiring procedures to handle data transfers for a circular stack. However, this method
also leaves less RAM space for variables or code. The RAM area that may effectively be
Data Sheet
STKSZ in register SYSCON).
These values are then tested in the stack underflow and overflow trap routines when
moving data.
plus six words (for the reserved space to store two interrupt entries).
(STKSZ = ‘000
uses the complete internal RAM for system stack. In the latter case the address
transformation mechanism is deactivated.
B
’ to ‘100
B
’), it does not work with option STKSZ = ‘111
403
B
’), where the system stack may
System Programming
2001-04-19
B
’, which
C161U