ST52T440F3M6 STMicroelectronics, ST52T440F3M6 Datasheet - Page 37

• Manufacturer Part Number: ST52T440F3M6
• Description: MCU 8-Bit ST52 CISC 8KB EPROM 5V 20-Pin SO
• Manufacturer: STMicroelectronics

Specifications of ST52T440F3M6

• Package: 20SO
• Family Name: ST52
• Maximum Speed: 20 MHz
• Ram Size: 256 Byte
• Program Memory Size: 8 KB
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 13
• On-chip Adc: 6-chx12-bit
• Operating Temperature: -40 to 85 °C
• Number Of Timers: 1

4 INTERRUPTS
The Control Unit (CU) responds to peripheral
events and external events via its interrupt chan-
nels.
When such an events occur, if the related interrupt
is not masked and according to a priority order,
the current program execution can be suspended
to allow the CU to execute a specific response
routine.
Each interrupt is associated with an interrupt vec-
tor that contains the memory address of the
related interrupt service routine. Each vector is
located in the Program Space (EPROM Memory)
at a fixed address (see Interrupt Vectors Figure
4.2).
4.1 Interrupt Operation
If there are pending interrupts at the end of an
arithmetic or logic instruction, the one with the
highest priority is passed. Passing an interrupt
means to store the arithmetic flags and the current
PC in the stack and execute the associated Inter-
rupt routine, whose address is located in three
bytes of the EPROM memory location between
address 3 and 20.
The Interrupt routine is performed as a normal
code checking, at the end of each instruction, if a
higher priority interrupt has to be passed. An Inter-
rupt request with the higher priority stops the
lower priority Interrupt. The Program Counter and
the arithmetic flags are stored in the stack.
With the instruction RETI (Return from Interrupt)
the arithmetic flags and Program Counter (PC) are
restored from the top of the stack, which was pre-
viously described in Section 2.2.1.
An Interrupt request cannot stop fuzzy rule pro-
cessing, but this is passed only after the end of a
fuzzy rule or at the end of a logic, or arithmetic
instruction.
REMARK: A fuzzy routine can be interrupted only
in the Main program. When a Fuzzy function is
running inside another interrupt routine an inter-
rupt request can cause side effects in the Control
Unit. For this reason, in order to use a Fuzzy func-
tion inside an interrupt routine, the user MUST
include the Fuzzy function between an UDGI
(MDGI) instruction and and UEGI (MEGI) instruc-
tion (see the following paragraphs), in order to dis-
able the interrupt request during the execution of
the fuzzy function.
Figure 4.1 Interrupt Flow
Figure 4.2 Interrupt Vectors Mapping
Figure 4.3 Global Interrupt Request Generation
Global Interrupt
Pending
User Global
Interrupt Mask
Macro Global
INTERRUPT
PROGRAM
NORMAL
FLOW
10
11
12
13
14
15
16
17
18
19
20
ST52T400/T440/E440/T441
0
1
2
3
4
5
6
7
8
9
INT_TIMER/PWM
INT_TRIAC/F
INT_TRIAC/R
INT_TRIAC/P
INT_EXT
RESET
INT_AC
INSTRUCTION
INTERRUPT
Global Interrupt
Request
SERVICE
ROUTINE
RETI
INTERRUPT
VECTORS
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