EMC6D100-DK SMSC [SMSC Corporation], EMC6D100-DK Datasheet - Page 42

• Manufacturer Part Number: EMC6D100-DK
• Description: ENVIRONMENTAL MONITORING AND CONTROL DEVICE WITH AUTOMATIC FAN CAPABILITY
• Manufacturer: SMSC [SMSC Corporation]

8.6
8.7
SMSC EMC6D100/EMC6D101
REGISTER
REGISTER
ADDRESS
ADDRESS
2Ah
2Bh
2Ch
2Dh
2Eh
2Fh
28h
29h
30h
Registers 28-2Fh: Fan Tachometer Reading
The Fan Tachometer Reading registers contain the number of 11.111µs periods (90KHz) between full fan
revolutions. Fans produce two tachometer pulses per full revolution. These registers are updated at least
once every second.
This value is represented for each fan in a 16 bit, unsigned number.
The Fan Tachometer Reading registers always return an accurate fan tachometer measurement, even
when a fan is disabled or non-functional, including when the start bit=0.
When one byte of a 16-bit register is read, the other byte latches the current value until it is read, in order
to ensure a valid reading. The order is LSB first, MSB second.
FFFFh indicates that the fan is not spinning, or the tachometer input is not connected to a valid signal
(This could be triggered by a counter overflow).
These registers are read only – a write to these registers has no effect.
Registers 30-32h: Current PWM Duty
WRITE
WRITE
READ/
READ/
R/W
R
R
R
R
R
R
R
R
1
Fan1 Current
Tach1 MSB
Tach2 MSB
Tach3 MSB
Tach4 MSB
Tach2 LSB
Tach4 LSB
Tach1 LSB
Tach3 LSB
REGISTER
REGISTER
-127°c
-50°c
0°c
50°c
127°c
(SENSOR
ERROR)
TEMPERATURE
NAME
NAME
Table 8.2 - Temperature vs. Register Reading
DATASHEET
(MSB)
(MSB)
BIT 7
BIT 7
15
15
15
15
7
7
7
7
7
-127
-50
0
50
127
READING (DEC)
BIT 6
BIT 6
14
14
14
14
6
6
6
6
6
Page 42
BIT 5
BIT 5
13
13
13
13
5
5
5
5
5
BIT 4
BIT 4
12
12
12
12
4
4
4
4
4
81h
CEh
00h
32h
7Fh
80h
READING (HEX)
BIT 3
BIT 3
11
11
11
11
3
3
3
3
3
Environmental Monitoring and Control Device
BIT 2
BIT 2
10
10
10
10
2
2
2
2
2
BIT 1
BIT 1
1
9
1
9
1
9
1
9
1
(LSB)
(LSB)
BIT 0
BIT 0
0
8
0
8
0
8
0
8
0
Rev. 09-09-04
DEFAULT
DEFAULT
Datasheet
VALUE
VALUE
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A