External Reset Pin - Fujitsu F2MC-16LX Hardware Manual

CHAPTER 4 RESET
4.3

External Reset Pin

The external reset pin (RST pin), dedicated to reset input pin, generates an internal
reset in response to input of the "L" level signal. MB90330 series are reset in sync with
the CPU operating clock, except for external pin in asynchronous (generated through
ports and so on), which change to the reset state.
Block Diagram of External Reset Pin
Figure 4.3-1 shows the block diagram of the generation of the internal reset.
RST
Pin
HCLK : Oscillation clock
Note:
To protect the memory from destruction by a reset during write operation, the RST pin input is
accepted with a cycle which does not cause the memory to be destroyed.
Also, the clock is required to initialize the internal circuits. In particular, when using an external clock,
the clock must be input during input of the reset.
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Figure 4.3-1 Block Diagram of Internal Reset Generation
Pch
Nch
Input buffer
CPU operation clock
(PLL frequency multiplication circuit,
divided-by-two of HCLK)
Synchronous
circuit
CPU
Peripheral
function
I/O port
etc.