Scan IF Operation
30-32
Scan IF
30.2.7 Using the Scan IF With Resistive Sensors
Systems with GMRs use magnets on an impeller to measure rotation. The
damping material and magnets modify the electrical behavior of the sensor so
that rotation and direction can be detected.
Rotation is measured with resistive sensors by connecting the resistor dividers
to ground for a short time allowing current flow through the dividers. The
resistors are affected by the rotating disc creating different divider voltages.
The divider voltages are sampled with the sample-and-hold circuits. After the
signals have settled the dividers may be switched off to prevent current flow
and reduce power consumption. The DAC is used to set the reference level
for the comparator, and the comparator detects if the sampled voltage is above
or below the reference level. If the sampled voltage is above the reference
level the comparator output is high. Figure 30−18 shows the connection for
resistive sensors.
Figure 30−18. Resistive Sensor Connections
Power
Supply
Terminals
SIFCI0
SIFCI
SIFCI1
SIFCI2
SIFCI3
470 nF
AV
CC
DV
CC
DV
SS
AV
SS
SIFVSS
SIFCOM
SIFCH1
SIFCH0
SIFCH2
SIFCH3
Summary of Contents for MSP430x4xx Family
Page 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Page 2: ......
Page 6: ...vi ...
Page 114: ...3 76 RISC 16 Bit CPU ...
Page 304: ...5 20 FLL Clock Module ...
Page 340: ...7 8 Supply Voltage Supervisor ...
Page 348: ...8 8 16 Bit Hardware Multiplier ...
Page 372: ...9 24 32 Bit Hardware Multiplier ...
Page 400: ...10 28 DMA Controller ...
Page 428: ...13 10 Basic Timer1 ...
Page 466: ...15 24 Timer_A ...
Page 522: ...17 30 USART Peripheral Interface UART Mode ...
Page 544: ...18 22 USART Peripheral Interface SPI Mode ...
Page 672: ...23 12 Comparator_A ...
Page 692: ...24 20 LCD Controller ...
Page 746: ...26 28 ADC12 ...