Rabbit Rabbit 4000, User Manual

Page: 46 / 358

36 Rabbit 4000 Microprocessor User’s Manual
4.4 Register Descriptions
Global Control/Status Register (GCSR) (Address = 0x0000)
Bit(s) Value Description
7:6 00 No reset or watchdog timer timeout since the last read.
(rd-only) 01 The watchdog timer timed out. These bits are cleared by a read of this register.
10 This bit combination is not possible.
11 Reset occurred. These bits are cleared by a read of this register.
5 0 No effect on the periodic interrupt. This bit will always be read as zero.
1 Force a periodic interrupt to be pending.
4:2 000
Processor clock from the main clock, divided by eight.
Peripheral clock from the main clock, divided by eight.
001
Processor clock from the main clock, divided by eight.
Peripheral clock from the main clock.
010
Processor clock from the main clock.
Peripheral clock from the main clock.
011
Processor clock from the main clock, divided by two.
Peripheral clock from the main clock, divided by two.
100
Processor clock from the 32 kHz clock, optionally divided via GPSCR.
Peripheral clock from the 32 kHz clock, optionally divided via GPSCR.
101
Processor clock from the 32 kHz clock, optionally divided via GPSCR.
Peripheral clock from the 32 kHz clock, optionally divided via GPSCR.
The main clock is disabled.
110
Processor clock from the main clock, divided by four.
Peripheral clock from the main clock, divided by four.
111
Processor clock from the main clock, divided by six.
Peripheral clock from the main clock, divided by six.
1:0 00 Periodic interrupts are disabled.
01 Periodic interrupts use Interrupt Priority 1.
10 Periodic interrupts use Interrupt Priority 2.
11 Periodic interrupts use Interrupt Priority 3.