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IDT Clocking and Initialization
Reset and Initialization
79RC32438 User Reference Manual
3 - 4
November 4, 2002
Notes
Figure 3.3 Cold Reset
Figure 3.4 PCI Reset in Host Mode
Boot Configuration Vector
The boot configuration vector is read by the RC32438 during a cold reset. The vector defines essential
RC32438 parameters that are required once the cold reset completes.
The encoding of boot configuration vector is described in Table 3.3, and the vector input is illustrated in
Figure 3.5. The value of the boot configuration vector read in by the RC32438 during a cold reset may be
determined by reading the Boot Configuration Vector (BCV) Register.
BOOT VECT
CLK
COLDRSTN
RSTN
MDATA[15:0]
BDIRN
BOEN
>= 4096 CLK clock cycles
1
2
3
4
5
6
FFFF_FFFF
1.
COLDRSTN asserted by external logic.
The RC32438 asserts RSTN, asserts BOEN low, drives BDIRN low, disables EXTCLK, and tri-
states the data bus and all output pins in response.
2.
External logic begins driving valid boot configuration vector on the data bus, and the RC32438 starts sampling it.
3.
External logic negates COLDRSTN and tri-states the boot configuration vector on MDATA[15:0]. The boot configuration vector must not
be tri-stated before COLDRSTN is negated. The RC32438 stops sampling the boot configuration vector.
4.
The RC32438 starts driving the data bus, MDATA[15:0], negates BOEN, drives BDIRN high, and starts driving EXTCLK.
5.
RSTN negated by the RC32438.
6.
CPU begins executing by taking MIPS reset exception, and the RC32438 starts sampling RSTN as a warm reset input.
<= 16 CLK
>= 4096 CLK clock cycles
EXTCLK
PCI interface enabled
cold reset
warm reset
COLDRSTN
PCIRSTN (output)
RSTN
Note: During and after cold reset, PCIRSTN is tri-stated and requires a pull-down to reach a low state.
After the PCI interface is enabled in host mode, PCIRSTN will be driven high and low depending on the
reset state of the 79RC32438.
(tri-state)