TCP872 V1.0 User Manual Issue 1.1
Page 14 of 16
4.3 ISA Interrupts
The TCP872 provides a possibility to gain access to parallel or serialized ISA IRQ signals on board.
With the default EEPROM download configuration the PCI1520 is initialized to generate serial ISA
IRQs on MFUNC3. For other IRQ configurations, the PCI1520 PC Card controller must be initialized
through the controller’s device driver. Interrupt signaling can be provided through the PCI1520
multifunction pins MFUNC3 and MFUNC6. MFUNC3 can be configured to function as serial or parallel
ISA IRQ 2 to 15. MFUNC6 can be configured to function as parallel ISA IRQ 2 to 15. To enable the
parallel ISA IRQs on these pins the following settings must be done by software:
Register
Offset
Required Value
ISA Routing
Multifunction routing
0x8C
Bits 27-24: 0x2 - 0xF
MFUNC6 is IRQ 2 -15
Multifunction routing
0x8C
Bits 15-12: 0x2 - 0xF
MFUNC3 is IRQ 2 -15
Device control
0x92
Bits 2–1: 0x01
Parallel ISA and PCI interrupts enabled
ExCA interrupt control
0x03
Bits 3-0: 0x3-0xF
IRQ 3-15 enabled
Figure 4-3 : ISA Interrupts
For further information please refer to the PCI1520 data sheet which is part of the TCP872-ED
Engineering Documentation.
The ISA IRQ signal of MFUNC3 can be accessed by routing the signal via a 0 ohm resistor to the
CompactPCI connector J1 Pin E4. The IRQ signal of MFUNC6 can be accessed by routing the signal
via a 0 ohm resistor to the CompactPCI connector J1 Pin D4.
