isl3873b Intersil Corporation, isl3873b Datasheet - Page 17

• Manufacturer Part Number: isl3873b
• Description: Wireless Integrated Medium Access Controller With Baseband Processor
• Manufacturer: Intersil Corporation

• When using a 48MHz CLKIN, as is typical for 802.11 or
The MCLK prescaler is set to divide by 16 at hardware reset
to allow initialization firmware to be executed from slow
memory devices at any CLKIN frequency. The MCLK
prescaler generates glitch free output when the divisor is
changed. This allows firmware to change the MCLK
frequency during operation, which is especially useful to
selectively reduce operating speed, thereby conserving
power, when full speed processing is not required.
NOTE: The operating frequency of the serial port is 400kHz with a voltage of 3.3V.
a. FCRinIO = 1 forces HAMASK [0] = 1 to expand I/O space decoding from 0 x 40 to 0 x 80 bytes.
15:14 NVtype[1:0]
BITS
5:0
13
12
11
10
802.11b controllers with a USB host interface, common
divisors are 4 (12MHz) or 6 (8MHz)
9
8
7
6
MD15
0
0
1
SHIenable
ISAmode
FCRinIO
ROMds
Mem16
NAME
StrIdle
4Wire
Spare
NVds
XTALOUT
XTALIN
FIGURE 11. 32.768kHz CRYSTAL
MD14
X
0
1
DEFAUL
0 x 00
30
T
0
1
0
0
0
1
0
0
AT45DB011
24C08 (Note)
None
X1
DEVICE TYPE
Indicates type of serial NV memory to be read by initialization firmware in on-chip ROM.
Up to 8 NV device types can be encoded with (StrIdle or NVtype). If StrIdle = 0, NV memory holds a firmware image,
and NVtype identifies 1 of 4 “large” (. = 128Kb) types. If StrIdle = 1, the NV memory just holds the CIS, and NVtype
identifies 1 of 4 “small” (< = 8Kb) types.
Use the Serial Host Interface (USB), and disable all PC Card functions except attribute space, for access to the
COR and HCR for firmware debugging support. When = 0, use the Parallel Host Interface (PC Card or ISA).
Use 4-wire interface to SRAM (CS-, OE-, WEH-, WEL-) the ISL3873B x8 SRAMs. When = 0 selects 5-wire interface
for use with x16 SRAM (CS-, OE-, WE-, UBE-, LBE-).
Start idle (wait for download from PC Card host interface).
RAM and NV space at startup is x 16. When = 0 RAM and NV space at startup is x 8. If starting from off-chip NV
memory this setting must indicate the width of the startup Flash Memory. During initialization, firmware can set
separate widths or RAM and NV space in the Memory Control Register.
Disable mapping of off-chip control store to NV space (hence map off-chip control store to RAM space). When = 0
off-chip control store is mapped to NV memory
Disable on-chip control store ROM. When = 0 enable on-chip control store ROM.
Set host interface control signals and address decoding for PC card. When = 1 set host interface signals and
address decoding is for ISA bus, with all registers in I/O space and attribute space disabled. To use ISA mode,
PHIenable must be = 1 to enable a parallel host interface.
Enable I/O space decoding for the physical FCRs. When = 1, the COR, CSR, and PRR registers are accessible at
I/O space offsets 0x40, 0x42, and 0x44 respectively. When = 0 these registers are only accessible in attribute
space. This bit is ignored when PHIenable = 0, and is overridden (forced = 1) when ISAmode =1. FCRinIO = 1 is
useful for PC Card operation (PHIenable = 1, ISAmode = 0) to allow non-OS software to access the COR/HCR in
OS environments where the system software does not permit application software to access attribute space.
Not assigned.
17
TABLE 3. INITIALIZATION STRAPPING OPTIONS ON MBUS DATA PINS
10M
4700pF
22pF
C1
C2
Large Serial Device used to transfer firmware to SRAM
Small Serial Device which contains only CIS. MAC goes idle after loading CIS and waits for host.
Modes not supported in firmware at this time. Consult factory for additional device types added.
TABLE 4. SERIAL EEPROM SELECTION
ISL3873B
Power On Reset Configuration
Power On Reset is issued to the ISL3873B with the RESET
pin or via the soft reset bit, SRESET, in the Configuration
Option Register (COR, bit 7). RESET originates from the
HOST system which applies RESET for at least 0.01ms after
V
standard, Vol. 2, Ch. 4.12.1).
The MD[15:8] pin values are sampled during RESET or
Software Reset (SRESET). These pins have internal 50K
resistors. External pull-up or pull-down resistors (typically
10k ) are used for bits which need to be configured
differently than the default.
Table 3 summarizes the effect per pin. Table 4 provides the
MD15 and MD14 bit values required to allow the ISL3873B
to use Serial EEPROM option.
MD[11], StrIdle, has no equivalent functionality in any control
register. When asserted at reset, it will inhibit firmware
execution. This is used to allow the initial download of
firmware in “Genesis Mode”. See the Hardware Reference
Manual for more details. The latch is cleared when the
Software Reset, SRESET, COR(7) is active.
CC
FUNCTION
has reached 90% of its end value (see PC-Card
FUNCTION
b