SDA5252 SIEMENS [Siemens Semiconductor Group], SDA5252 Datasheet - Page 72

• Manufacturer Part Number: SDA5252
• Description: TVTEXT 8-Bit Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Semiconductor Group
6.3.4.2
The external interrupt request inputs (INT0 and INT1) can be programmed for either
transition- activated or level-activated operation. Control of the external interrupts is
provided by the four low- order bits of TCON as shown in the follow section.
When IT0 and IT1 are set to one, interrupt requests on INT0 and INT1 are transition-
activated (high-to-low), else they are low-level activated. IE0 and IE1 are the interrupt
request flags. These flags are set when their corresponding interrupt request inputs at
INT0 and INT1, respectively, are low when sampled by the processor and the transition-
activated scheme is selected by IT0 and IT1.
Function of Lower Nibble Bits in TCON
Timer and Interrupt Control
Register
Default after reset: 00
TCON.4 – TCON.7
IE1
IT1
IE0
IT0
(MSB)
TF1
External Interrupts
TR1
H
See Chapter “General Purpose Timers/Counters” on
page 80.
Interrupt 1 edge flag. Set by hardware when external interrupt
edge detected. Cleared when interrupt processed.
Interrupt 1 type control bit. Set/cleared by software to specify
falling edge/low level triggered external interrupts. IT1 = 1
selects transition-activated external interrupts.
Interrupt 0 edge flag. Set by hardware when external interrupt
edge detected. Cleared when interrupt processed.
Interrupt 0 type control bit. Set/cleared by software to specify
falling edge/low level triggered external interrupts. IT0 = 1
selects transition-activated external interrupts.
TF0
TR0
TCON
72
IE1
IT1
SFR-Address 88
IE0
SDA 525x
1998-04-08
(LSB)
IT0
H