71M6533 Datasheet, PDF (31/132 Pages) Teridian Semiconductor Corporation – Energy Meter IC

FDS_6533_6534_004
71M6533/G/H and 71M6534/H Data Sheet
is terminated by a return from instruction, RETI. When an RETI is performed, the processor will return to
the instruction that would have been next when the interrupt occurred.
When the interrupt condition occurs, the processor will also indicate this by setting a flag bit. This bit is
set regardless of whether the interrupt is enabled or disabled. Each interrupt flag is sampled once per
machine cycle, then samples are polled by the hardware. If the sample indicates a pending interrupt
when the interrupt is enabled, then the interrupt request flag is set. On the next instruction cycle, the interrupt
will be acknowledged by hardware forcing an LCALL to the appropriate vector address, if the following
conditions are met:
• No interrupt of equal or higher priority is already in progress.
• An instruction is currently being executed and is not completed.
• The instruction in progress is not RETI or any write access to the registers IEN0, IEN1, IEN2, IP0 or IP1.
Special Function Registers for Interrupts
The following SFR registers control the interrupt functions:
• The interrupt enable registers: IEN0, IEN1 and IEN2 (see Table 24, Table 25 and Table 26).
• The Timer/Counter control registers, TCON and T2CON (see Table 27 and Table 28).
• The interrupt request register, IRCON (see Table 29).
• The interrupt priority registers: IP0 and IP1 (see Table 34).
Bit
IEN0[7]
IEN0[6]
IEN0[5]
IEN0[4]
IEN0[3]
IEN0[2]
IEN0[1]
IEN0[0]
Table 24: The IEN0 Bit Functions (SFR 0xA8)
Symbol
EAL
WDT
–
ES0
ET1
EX1
ET0
EX0
Function
EAL = 0 disables all interrupts.
Not used for interrupt control.
Not Used.
ES0 = 0 disables serial channel 0 interrupt.
ET1 = 0 disables timer 1 overflow interrupt.
EX1 = 0 disables external interrupt 1.
ET0 = 0 disables timer 0 overflow interrupt.
EX0 = 0 disables external interrupt 0.
Bit
IEN1[7]
IEN1[6]
IEN1[5]
IEN1[4]
IEN1[3]
IEN1[2]
IEN1[1]
IEN1[0]
Table 25: The IEN1 Bit Functions (SFR 0xB8)
Symbol
–
–
EX6
EX5
EX4
EX3
EX2
–
Function
Not used.
Not used.
EX6 = 0 disables external interrupt 6: XFER_BUSY, RTC_1SEC, WD_NROVF
EX5 = 0 disables external interrupt 5: EEPROM_BUSY
EX4 = 0 disables external interrupt 4: PLL_OK (rise), PLL_OK (fall)
EX3 = 0 disables external interrupt 3: CE_BUSY
EX2 = 0 disables external interrupt 2: FWCOL0, FWCOL1, SPI
Not Used.
Bit
IEN2[0]
Table 26: The IEN2 Bit Functions (SFR 0x9A)
Symbol Function
ES1 ES1 = 0 disables the serial channel 1 interrupt.
Rev 2
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