II CORE BLOCK: INITIAL RESET
Boot Address
When the core CPU is initially reset, it reads the reset vector (program start address) from the boot address (0x0C00000) and loads the vector to the PC (program counter). Then the CPU starts executing the program from the address when the #RESET pin goes high.
The trap table in which trap vectors for interrupts and other trap factors are written also begins from the boot address by the default setting. (Refer to the "S1C33000 Core CPU Manual" for details of the trap table.)
The trap table base address can also be changed to a 1KB boundary address using the TTBR register (0x48134 to 0x48137).
Notes Related to Initial Reset
Core CPU
Since the all registers except for the PC and PSR are indeterminate at initial reset, they should be initialized |
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by a program. In particular, the SP (stack pointer) must be initialized before accessing the stack area. NMI |
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requests are disabled until any value is written to the SP. The initialization is necessary when the CPU is |
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Internal RAM
The contents of the internal RAM are indeterminate at initial reset. Initialize the area to be used if necessary.
An initial reset activates the
A
BCU (Bus Control Unit)
Input/output ports and input/output pins
Cold start initializes the control and data registers for the input and I/O ports.
Hot start retains the contents of the control registers and input/output pin status before an initial reset. However, when the pins are used for the internal peripheral circuits, it is necessary to set up the control registers of the peripheral circuit because they are initialized by an initial reset.
Other internal peripheral circuits
The control and data registers of peripheral circuits other than those listed above are initialized with the predefined values or become indeterminate regardless of the reset method (cold start or hot start). Therefore, it is necessary to set up the peripheral circuit conditions.
Refer to the I/O maps or explanation of each peripheral circuit section for initial settings of the peripheral circuits.
Reset
S1C33L03 FUNCTION PART | EPSON |