33970 Datasheet, PDF (21/36 Pages) Freescale Semiconductor, Inc – Dual Gauge Driver Integrated Circuit with Improved Damping Algorithms

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
• 1 = Return to Zero enabled successfully
ACC14:ACC0 (OD14:OD0) — These 15 bits are from the
RTZ accumulator. They represent the integrated signal
present on the non-driven coil during an RTZ event. These
bits are logic [0] after power-on reset, or after the RST pin
transitions from logic [0] to [1]. After an RTZ event, they will
represent the last RTZ accumulator result before the RTZ
was stopped. ACC14 is the MSB and is the sign bit used for
zero detection.
The analog-to-digital converter's linear input range covers
the expected magnitude of motor back e.m.f. signals, which
is_usually less than 500mV. Input signals greater than this
will not cause any damage (the circuit is connected to the
motor H-Bridge drivers, and thus is exposed to the full
magnitude of the drive voltages), but may cause some small
loss of linearity. A typical plot of output vs. input is shown in
Figure 8 for 4ms step times.
Gauge 0 Pointer Position Status Information
Most recent valid PECCR command resulting in the
Gauge 0 Pointer Position status output:
D11
D10
D9
D8
1
1
0
0
Figure 8. RTZ Accumulator (Typical)
Table 17. Gauge 0 Pointer Position Status Output Register
Bits OD15 OD14 OD13 OD12 OD11 OD10 OD9 OD8 OD7 OD6 OD5 OD4 OD3 OD2 OD1 OD0
Read ENB0 DIR0 DIRC0 CMD0 POS11 POS10 POS9 POS8 POS7 POS6 POS5 POS4 POS3 POS2 POS1 POS0
Write –
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
The bits in Table 17 are read-only bits.
ENB0 (OD15) — This bit indicates whether Gauge 0 is
enabled.
• 0 = Disabled
• 1 = Enabled
DIR0 (OD14) — This bit indicates the direction Gauge 0 is
moving.
• 0 = Toward position 0
• 1 = Away from position 0
DIRC0 (OD13) — This bit is used to determine whether the
direction of the most recent pointer movement is toward the
last commanded position or away from it.
• 0 = Direction of the pointer movement is toward the
commanded position
• 1 = Direction of the pointer movement is away from the
commanded position
CMD0 (OD12) — This bit indicates whether Gauge 0 is at
the most recently commanded position.
• 0 = At commanded position
• 1 = Not at commanded position
POS11:POS0 (OD11:OD0) — These 12 bits represent the
actual position of the pointer at the time CS transitions to a
logic [0].
Gauge 1 Pointer Position Status Information
Most recent valid PECCR command resulting in the
Gauge 1 Pointer Velocity status output:
D11
D10
D9
D8
1
1
0
1
Table 18. Gauge 1 Pointer Position Status Output Register
Bits OD15 OD14 OD13 OD12 OD11 OD10 OD9 OD8 OD7 OD6 OD5 OD4 OD3 OD2 OD1 OD0
Read ENB1 DIR1 DIRC1 CMD1 POS11 POS10 POS9 POS8 POS7 POS6 POS5 POS4 POS3 POS2 POS1 POS0
Write –
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Analog Integrated Circuit Device Data
Freescale Semiconductor
33970
21