SAF-C161U-LF V1.3 Infineon Technologies, SAF-C161U-LF V1.3 Datasheet - Page 118

• 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

C161U
Interrupt and Trap Functions
7.4
Prioritization of Interrupt and PEC Service Requests
Interrupt and PEC service requests from all sources can be enabled, so they are
arbitrated and serviced (if they win), or they may be disabled, so their requests are
disregarded and not serviced.
Enabling and disabling interrupt requests may be done via three mechanisms:
Control Bits allow to switch each individual source “ON” or “OFF”, so it may generate a
request or not. The control bits (xxIE) are located in the respective interrupt control
registers. All interrupt requests may be enabled or disabled generally via bit IEN in
register PSW. This control bit is the “main switch” that selects, if requests from any
source are accepted or not.
For a specific request to be arbitrated the respective source’s enable bit and the global
enable bit must both be set.
Priority Level automatically selects a certain group of interrupt requests that will be
acknowledged, disclosing all other requests. The priority level of the source that won the
arbitration is compared against the CPU’s current level and the source is only serviced,
if its level is higher than the current CPU level. Changing the CPU level to a specific value
via software blocks all requests on the same or a lower level. An interrupt source that is
assigned to level 0 will be disabled and never be serviced.
ATOMIC and EXTend instructions automatically disable all interrupt requests for the
duration of the following 1...4 instructions. This is useful eg. for semaphore handling and
does not require to re-enable the interrupt system after the unseparable instruction
sequence (see chapter “System Programming”).
Interrupt Class Management
An interrupt class covers a set of interrupt sources with the same importance, ie. the
same priority from the system’s viewpoint. Interrupts of the same class must not interrupt
each other. C161U supports this function with two features:
Classes with up to 4 members can be established by using the same interrupt priority
(ILVL) and assigning a dedicated group level (GLVL) to each member. This functionality
is built-in and handled automatically by the interrupt controller.
Classes with more than 4 members can be established by using a number of adjacent
interrupt priorities (ILVL) and the respective group levels (4 per ILVL). Each interrupt
service routine within this class sets the CPU level to the highest interrupt priority within
the class. All requests from the same or any lower level are blocked now, ie. no request
of this class will be accepted.
The example below establishes 3 interrupt classes which cover 2 or 3 interrupt priorities,
depending on the number of members in a class. A level 6 interrupt disables all other
sources in class 2 by changing the current CPU level to 8, which is the highest priority
(ILVL) in class 2. Class 1 requests or PEC requests are still serviced in this case.
Data Sheet
118
2001-04-19