mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 643

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

17.4.4.2
The arbitration scheme allows only one master to be connected to a target at any given time. The following
rules apply when prioritizing accesses from different masters to the same target bus:
17.4.5
17.4.5.1
The following interrupt requests can be triggered by the MMC module:
CPU access violation: The CPU access violation signals to the CPU detection of an error condition in the
CPU application code which is resulted in write access to the protected XGATE RAM area (see
Section 1.4.3.2, “Illegal CPU
17.5
17.5.1
CALL and RTC instructions are uninterruptable CPU instructions that automate page switching in the
program page window. The CALL instruction is similar to the JSR instruction, but the subroutine that is
called can be located anywhere in the local address space or in any Flash or ROM page visible through the
program page window. The CALL instruction calculates and stacks a return address, stacks the current
PPAGE value and writes a new instruction-supplied value to the PPAGE register. The PPAGE value
controls which of the 256 possible pages is visible through the 16 Kbyte program page window in the
64 Kbyte local CPU memory map. Execution then begins at the address of the called subroutine.
During the execution of the CALL instruction, the CPU performs the following steps:
Freescale Semiconductor
•
•
•
•
•
1. Writes the current PPAGE value into an internal temporary register and writes the new
2. Calculates the address of the next instruction after the CALL instruction (the return address) and
3. Pushes the temporarily stored PPAGE value onto the stack
4. Calculates the effective address of the subroutine, refills the queue and begins execution at the new
CPU always has priority over XGATE.
BDM access has priority over XGATE.
XGATE access to PRU registers constitutes a special case. It is always granted and stalls the CPU
and BDM for its duration.
In emulation modes all internal accesses are visible on the external bus as well.
During access to the PRU registers, the external bus is reserved.
instruction-supplied PPAGE value into the PPAGE register
pushes this 16-bit value onto the stack
address
Initialization/Application Information
Interrupts
CALL and RTC Instructions
Access Conflicts on Target Buses
Outgoing Interrupt Requests
Accesses”).
MC9S12XDP512 Data Sheet, Rev. 2.17
Chapter 17 Memory Mapping Control (S12XMMCV2)
643