BCM1250/BCM1125/BCM1125H
User Manual
10/21/02
B r o a d c o m C o r p o r a t i o n
Page
44
Section 4: System Control and Debug Unit
Document
1250_1125-UM100CB-R
19
pci_host
ext
Read Only, reflects the strap resistor on generic IO_AD[19], that configures the
PCI interface to be host or device mode.
20
pci_arbiter
ext
Read Only, reflects the strap resistor on generic IO_AD[20], that configures the
PCI interface to use an internal or external arbiter. (If the PCI is set in device mode
the resistor must be set for an external arbiter)
21
southOnLDT
ext
Read Only, reflects the strap resistor on generic IO_AD[21], that configures the
southbridge to be on the HyperTransport fabric or PCI bus.
22
big_endian
ext
Read Only, reflects the strap resistor on generic IO_AD[22], that configures the
system to be big or little endian.
23
genclk_en
ext
Read Only, reflects the strap resistor on generic IO_AD[23], that enables output of
the generic bus clock on IO_CLK100. If this bit is zero then the IO_CLK100 will be
held in a high impedance state.
24
ldt_test_en
ext
Read Only, reflects the strap resistor on IO_AD[24]. Broadcom Use Only.
This must be zero for normal operation.
25
gen_parity_en
ext
Read Only, reflects the strap resistor on generic IO_AD[25] that configured the
generic bus parity.
31:26
config
ext
Read Only, reflects the strap resistor on generic IO_AD[31:26]. These
configuration bits are available for interpretation by software.
32
clkstop
1'b0
Writable via JTAG only. Broadcom use only.
33
clkstep
1'b0
Writable via JTAG only. Broadcom use only.
41:34
clkcount
8'b0
Writable via JTAG only. Broadcom use only.
42
pllbypass
1'b0
Writable via JTAG only. Broadcom use only.
44:43
pll_iref
2'b0
Writable via JTAG only. Broadcom use only.
46:45
pll_vco
2'b0
Writable via JTAG only. Broadcom use only.
48:47
pll_vreg
2'b0
Writable via JTAG only. Broadcom use only.
49
mem_reset
1'b0
Writable via JTAG only. When set the memory controller is held in reset.
50
l2c_reset
1'b0
Writable via JTAG only. When set the level 2 cache is held in reset.
51
io_reset_0
1'b0
Writable via JTAG only. When set the I/O bridge to the PCI and HyperTransport
fabric is held in reset.
52
io_reset_1
1'b0
Writable via JTAG only. When set the I/O bridge to the slow speed devices and
generic bus is held in reset.
53
scd_reset
1'b0
Writable via JTAG only. When set the SCD is held in reset.
54
cpu_reset_0
1'b0
Always reads as zero. When written with a 1 a standard length reset pulse is
delivered to CPU 0. (A device reset will also cause a standard length reset pulse
to CPU 0).
55
cpu_reset_1
1'b1
When set CPU 1 will be held in reset. This bit is set on a device reset, causing the
processor to remain in reset until released under software control.
56
unicpu0
1'b0
Set to indicate uniprocessor using physical processor 0.
(This bit will always be set on the BCM1125/H.)
57
unicpu1
1'b0
Set to indicate uniprocessor using physical processor 1. (BCM1250 only)
58
sb_softres
1'b0
When a write changes this bit from a 0 to a 1 a soft reset will be performed. This
will reset of whole chip except for this register. Note that once it is set the bit must
be cleared before writing a 1 will again cause a soft reset.
59
ext_reset
1'b0
When set the RESETOUT_L pin will be asserted.
Table 15: System Configuration Register
(Cont.)
system_cfg -
00_1002_0008
Bits
Name
Default
Description