UPSD3234AV-24U1T STMicroelectronics, UPSD3234AV-24U1T Datasheet - Page 37

• Manufacturer Part Number: UPSD3234AV-24U1T
• Description: Flash Programmable System Devices with 8032 Microcontroller Core and 64Kbit SRAM
• Manufacturer: STMicroelectronics

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Interrupt Priority Structure
Each interrupt source can be assigned one of two
priority levels. Interrupt priority levels are defined
by the interrupt priority special function register IP
and IPA.
0 = low priority
1 = high priority
A low priority interrupt may be interrupted by a
high priority interrupt level interrupt. A high priority
interrupt routine cannot be interrupted by any oth-
er interrupt source. If two interrupts of different pri-
ority occur simultaneously, the high priority level
request is serviced. If requests of the same priority
are received simultaneously, an internal polling
sequence determines which request is serviced.
Thus, within each priority level, there is a second
priority structure determined by the polling se-
quence.
Interrupts Enable Structure
Each interrupt source can be individually enabled
or disabled by setting or clearing a bit in the inter-
rupt enable special function register IE and IEA. All
Table 20. Description of the IE Bits
Table 21. Description of the IEA Bits
Bit
Bit
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
Symbol
Symbol
EDDC
EUSB
EI2C
EX1
EX0
ES2
ET2
ET1
ET0
EA
ES
—
—
—
—
—
Disable all interrupts:
0: no interrupt with be acknowledged
1: each interrupt source is individually enabled or disabled by setting or clearing its
enable bit
Reserved
Enable Timer 2 Interrupt
Enable USART Interrupt
Enable Timer 1 Interrupt
Enable external Interrupt (Int1)
Enable Timer 0 Interrupt
Enable external Interrupt (Int0)
Enable DDC Interrupt
Not used
Not used
Enable 2nd USART Interrupt
Not used
Not used
Enable I²C Interrupt
Enable USB Interrupt
uPSD3234A, uPSD3234BV, uPSD3233B, uPSD3233BV
interrupt source can also be globally disabled by
clearing Bit EA in IE.
Table 19. Priority Levels
Timer 2+EXF2
2nd USART
1st USART
Function
Function
Source
Timer 0
Timer 1
DDC
USB
Int0
Int1
I²C
Priority with Level
0 (highest)
9 (lowest)
1
2
3
4
5
6
7
8
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