SMSC DS – LPC47M192
Page 164
Rev. 03/30/05
DATASHEET
NAME
REG OFFSET
(hex)
58
(R/W)
DESCRIPTION
Fan Control
Default = 0x50
on VTR POR
Fan Control Register
Bit[0] Fan 1 Clock Source Select
This bit and the Fan 1 Clock Multiplier bit is used with
The Fan 1 Clock Select bit in the Fan 1 register (0x56) to
determine the fan speed F
OUT
. See Table 56 in “Fan
Speed Control and Monitoring” section.
Bit[1] Fan 2 Clock Source Select
This bit and the Fan 2 Clock Multiplier bit is used with
The Fan 2 Clock Select bit in the Fan 2 register (0x57) to
determine the fan speed F
OUT
. See Table 56 in “Fan
Speed Control and Monitoring” section.
Bit[2] Fan 1 Clock multiplier
0=No multiplier used
1=Double the fan speed selected by bit 0 of this
register and bit 7 of the FAN1 register
Bit[3] Fan 2 Clock multiplier
0=No multiplier used
1=Double the fan speed selected by bit 1 of this
register and bit 7 of the FAN2 register
Bit[5:4] The FAN1 count divisor. Clock scalar for
adjusting the tachometer count. Default = 2.
00: divisor = 1
01: divisor = 2
10: divisor = 4
11: divisor = 8
Bit[7:6] The FAN2 count divisor. Clock scalar for
adjusting the tachometer count. Default = 2.
00: divisor = 1
01: divisor = 2
10: divisor = 4
11: divisor = 8
Fan Tachometer Register 1
Bit]7:0] The 8-bit FAN1 tachometer count. The number
of counts of the internal clock per pulse of the fan. The
count value is computed from Equation 1. This value is
the final (maximum) count of the previous pulse
(latched). The value in this register may not be valid for
up to 2 pulses following a write to the preload register.
Fan Tachometer Register 2
Bit[7:0] The 8-bit FAN2 tachometer count. The number
of counts of the internal clock per pulse of the fan. The
count value is computed from Equation 1. This value is
the final (maximum) count of the previous pulse
(latched). The value in this register may not be valid for
up to 2 pulses following a write to the preload register.
Fan Preload Register 1
Bit[7:0] The FAN1 tachometer preload. This is the initial
value used in the computation of the FAN1 count.
Writing this register resets the tachometer count.
Fan1
Register
Default = 0x00
on VTR POR
Tachometer
59
(R)
Fan2
Register
Default = 0x00
on VTR POR
Tachometer
5A
(R)
Fan1
Register
Default = 0x00
on VTR POR
Preload
5B
(R/W)