84PCE:Ports:5000

Synopsis

Port Number: 7000-705F

Memory-mapped address: F00000

Function: Interrupt Controller

This port range is used to configure and control interrupts (appears to be model FTINTC010). There are two sets of interrupt control registers, but only the first actually triggers interrupts on the eZ80.

It is arranged in 22-bit bitfields (each occupying a little-endian 32-bit word), with each bit corresponding to a different interrupt source.

Known Sources

Bit	Interrupt Source
0	ON Button
1	Timer 1
2	Timer 2
3	Timer 3
4	Probably OS timer. Frequency is controlled by bits [1:0] of port 0000.
10	Keyboard
11	LCD Controller
12	Real-Time Clock
15	Unknown, but signal seems to be constantly on

Registers

Port	Default	Bits	Information
5000	Read-Only	003FFFFF	Raw interrupt status (can be either raw signal or latched on signal change from low-to-high).
5004	00003011	003FFFFF	Interrupt enable mask.
5008	Write-Only	003FFFFF	Interrupt acknowledge (used by ISR), seems to only affect latched status bits.
500C	00000019	003FFFFF	Determines whether bits of 5000 will latch. 0 means raw signal, 1 means latched.
5010	00000000	003FFFFF	Inverts the raw signal of the interrupts corresponding to each 1 bit. Can be used to latch on a high-to-low change.
5014	Read-only	003FFFFF	Masked interrupt status (used by ISR). Should be equal to (5000 & 5004).
5020			Ports 5020-503F are identical in function to 5000-501F. These registers do not actually trigger interrupts. Since this IP core was meant for use with ARM, these ports were intended to drive the FIQ signal, but the eZ80 has no such alternative interrupts. However, these ports can be used for other purposes such as reading the state of the ON key.
5050	Read-only	FFFFFFFF	Revision register. Reads 0x00010900 for revision 1.9.0.
5054	Read-only	FF	Feature register for input number (IRQ). Reads the number of normal interrupts configured to be handled by the controller, which is 22.
5055	Read-only	FF	Feature register for input number (FIQ). Reads the number of FIQ interrupts configured to be handled by the controller, which is 22.