20-668-0024 Rabbit Semiconductor, 20-668-0024 Datasheet - Page 276

• Manufacturer Part Number: 20-668-0024
• Description: IC CPU RABBIT4000 128-LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 20-668-0024

• Processor Type: Rabbit 4000 8-bit
• Speed: 60MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Other names: 20-668-0022; 316-1078

25.2 Dependencies
25.2.1 I/O Pins
There are no I/O pins associated with breakpoints.
25.2.2 Clocks
There are no clocks associated with breakpoints.
25.2.3 Other Registers
There are no other registers associated with breakpoints.
25.2.4 Interrupts
When an enabled address match occurs for a given breakpoint, a breakpoint interrupt
occurs. The breakpoint that caused the interrupt must be determined by reading BDCR,
which also clears the interrupt. Any of the breakpoint interrupts can be enabled by writing
to BDCR.
The breakpoint interrupt vector is in the EIR at offset 0x040. It is always set to Interrupt
Priority 3, and is the highest priority interrupt; if two Interrupt Priority 3 vectors are pend-
ing, the breakpoint interrupt will always be handled first.
25.3 Operation
The following steps must be taken to enable breakpoints:
1. Write the vector to the interrupt service routine to the external interrupt table.
2. Write the desired breakpoint addresses to the appropriate breakpoint address registers
3. Write an address mask for the given breakpoints (BxMyR).
4. Select the breakpoint address match type (execute, data read, data write) by writing to
5. Enable the desired breakpoints by writing to BDCR.
25.3.1 Handling Interrupts
The following actions occur within the interrupt service routine.
• Which breakpoints are pending should be determined by reading BDCR. This also
• The desired breakpoint action should be taken.
• If single-step functionality is desired, the breakpoint interrupt should be re-enabled by
266
(BxAyR, where x is the breakpoint and y is the byte of the address, 0-2).
the appropriate BxCR.
clears the pending breakpoints.
writing the appropriate bit to BDCR. If this is done, the interrupt handler needs to be
exited in a particular manner (see below).
Rabbit 4000 Microprocessor User’s Manual