EM6517 ETC, EM6517 Datasheet - Page 39

• Manufacturer Part Number: EM6517
• Description: 4 BIT MICROCONTROLLER
• Manufacturer: ETC

Figure 29. Interrupt Controller Block Diagram
13 Interrupt Controller
The EM6517-1 has 12 different interrupt request sources each of which is maskable. 4 of them are coming from
extarnal sources and 8 from internal.
External(4)
Internal(8)
Note : the interrupt request from Serial Output Buffer (SWBEmpty) in interactive mode can not be masked in
opposition to the others and goes directly to the CPU.
For interrupt requests except SWBEmpty interrupt :
and the general interrupt enable bit IntEn located in the register RegSysCntl1 must be set to 1. The interrupt
request flags can only be set high by a positive edge on the IRQxx data flip-flop while the corresponding mask
register bit (MaskIRQxx) is set to 1.
At power on or after any reset all interrupt request mask registers are cleared and therefore do not allow any
interrupt request to be stored. Also the general interrupt enable IntEn is set to 0 (No IRQ to CPU) by reset.
After each read operation on the interrupt request registers RegIRQ1, RegIRQ2 or RegIRQ3 the contents of the
addressed register are reset. Therefore one has to make a copy of the interrupt request register if there was
more than one IRQ to treat. Each interrupt request flag may also be reset individually by writing 1 into it .
Interrupt handling priority must be resolved through software by deciding which register and which flag inside
the register need to be serviced first.
Since the CPU has only one interrupt subroutine and the IRQxx registers are cleared after reading, the CPU
does not miss any interrupt request which comes during the interrupt service routine. If any occurs during this
time a new interrupt will be generated as soon as the software comes out of the current interrupt subroutine.
DB[n]
Write
IRQxx
Read
ClrIntBit
Reset
To be able to send an interrupt to the CPU, at least one of the interrupt request flags must ‘1’ (IRQxx)
One of these Blocks for each IRQ
Mask
- Port A,
- Prescaler
- 10-bit Counter
- EEPROM
- ADC
- VLD
- SWB (non-maskable)
Interrupt Request
FOR ENGINEERING ONLY
Capture Register
PA[3] .. PA[0] inputs
Ck[1], 32 Hz / 8 Hz
Count to 0, Count equal to Compare
End of writing operation
End of conversion
End of measure
SWB empty in interactive mode
DB
Write
12 Input-OR
SWBEmpty
General
INT En
Halt
© EM Microelectronic-Marin SA, 09/99, Rev. A/277
SWBAuto
EM6517
IRQ to µP
39