IC-TW14 Datasheet, PDF (19/33 Pages) IC-Haus GmbH – IC-PMX Companion Chip

iC-TW14
iC-PMX Companion Chip
Rev A1, Page 19/33
TEMP_SLOPE
TEMP_SLOPE is a read/write register containing the
slope of the iC-TW14’s temperature diode voltage with
respect to temperature.
VWP_FACTOR
VWP_FACTOR is a read/write register used to record
the value of the resistive voltage divider between
iC-PMX pin VWC and iC-TW14 pin VWP.
Value
±32,767
TEMP_SLOPE (0x20)
Description
Temperature voltage slope
Value
0 – 65,535
VWP_FACTOR (0x21)
Description
Scaled voltage divider ratio
Table 29: TEMP_SLOPE Register
Table 30: VWP_FACTOR Register
The TEMP_SLOPE register value is a 2’s complement
number calculated as
TEMP_SLOPE = INT(Slope[mV/^◦C] · 192)
VWP_FACTOR is calculated as
256
VWP_FACTOR = INT
Voltage Divider Ratio
It is used by the iC-TW14 to calculate the temperature
reported in the TEMP register. See TEMP on page 24
for more information.
For example, the typical temperature slope of the
temperature diode is –3.266 millivolts per °C, so
TEMP_SLOPE should be set to
INT(−3.266 · 192) = −627 = 0xFD8D
This value is not used directly by the iC-TW14, but al-
lows a connected computer to properly calculate the
Wiegand pulse voltage when using DIAG1 and DIAG2
modes. For example, if the voltage divider ratio is 1/3,
VWP_FACTOR = 768 = 0x0300.
MODE/CMD
MODE/CMD is a read/write register used to initiate di-
agnostic modes or execute commands.
TEMP_SLOPE can be calibrated by measuring the
die temperature of the iC-TW14 using an indepen-
dent thermometer at two different temperatures, T₁
and T₂ and recording the corresponding TEMP_RAW₁
and TEMP_RAW₂ values and the VDD register value.
TEMP_SLOPE is then calculated as
268, 435, 456
TEMP_SLOPE =
·
T₁ − T₂
VDD
TEMP_RAW ₁ − TEMP_RAW ₂
For example, suppose that at 30°C TEMP_RAW =
0x8F3D = 36669, at 80°C TEMP_RAW = 0x7EF5 =
32501, and VDD = 4895 mV. Then TEMP_SLOPE
should be set to
268, 435, 456 30 − 80
4895 ^· 36669 − 32501 ^{= −658}
This indicates an actual temperature slope of
–658/192 = –3.427 mV/°C.
Name
NORMAL
DIAG1
DIAG2P
DIAG2N
WRITE
READ
–
RESET
RESYNC
CLEAR
–
F_DATA_W
F_DATA_R
F_MT_W
F_MT_R
F_SET_MT
–
MRDY_LO
MRDY_HI
–
SSI_TEST
–
MODE/CMD (0x30)
Value
Description
0
Normal Operation
1
Diagnostic Mode 1
2
Diagnostic Mode 2 (Positive Ramp)
3
Diagnostic Mode 2 (Negative Ramp)
4
Write iC-TW14 Config. to FRAM
5
Read iC-TW14 Config. from FRAM
6
Reserved (do not use)
7
Reset iC-TW14
8
Re-synchronize iC-TW14 to iC-PMX
9
Clear Min/Max Values
10 – 20
Reserved (do not use)
21
FRAM Data Write
22
FRAM Data Read
23
FRAM Multiturn Position Write
24
FRAM Multiturn Position Read
25
Set FRAM Multiturn Position
26 – 29
Reserved (do not use)
30
Set iC-TW14 MRDY Pin Low
31
Set iC-TW14 MRDY Pin High
32 – 39
Reserved (do not use)
40
SSI Test Mode
41 – 65,535 Reserved (do not use)
Table 31: MODE/CMD Register
At startup, MODE/CMD = 0 (normal operation). To ini-
tiate a diagnostic mode or execute a command, write
the appropriate value to the Mode/Command register.
To cancel a diagnostic mode and return to normal op-
eration, re-synchronize the iC-TW14 to the iC-PMX by
writing 8 to MODE/CMD. When a READ (5), WRITE