33970 datasheet(19/36 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33970

FUNCTIONAL DEVICE OPERATION

LOGIC COMMANDS AND REGISTERS

Any bits clocked out of the SO pin after the first 16 are

representative of the initial message bits clocked into the SI

pin since the CS pin first transitioned to a logic [0]. This

feature is useful for daisy-chaining devices as well as

message verification.

As described above, the last valid write to bits PE11:PE8

of the PECCR command determines the nature of the status

data that is clocked out of the SO pin.

There are five different types of status information

available:

1. Device Status (refer to Table 15 below)

2. RTZ Accumulator Status (refer to Table 16, page 20)

3. Gauge 0 Pointer Position Status (refer to Table 17,

page 21)

4. Gauge 1 Pointer Position Status (refer to Table 18,

page 21)

5. Gauge 1 and 2 Pointer Velocity Status (refer to

Table 19, page 22)

Once a specific status type is selected, it will not change

until either the PECCR command bits PE11:PE8 (D11:D8)

are written to select another or the device is reset. Each of the

Status types and the PECCR bit necessary to select them are

described below.

Device Status Information

Most recent valid PECCR command resulting in the

Device Status output:

The bits in Table 15 are read-only bits.

DIR1 (OD15)—This bit indicates the direction Gauge 1

pointer is moving.

• 0 = Toward position 0

• 1 = Away from position 0

DIR0 (OD14)—This bit indicates the direction Gauge 0

pointer is moving.

• 0 = Toward position 0

• 1 = Away from position 0

0POS1 (OD13)—This bit indicates the configured Position

0 for Gauge 1.

• 0 = Farthest CCW

•1 = Farthest CW

0POS0 (OD12)—This bit indicates the configured Position

0 for Gauge 0.

• 0 = Farthest CCW

•1 = Farthest CW

CMD1 (OD11)—This bit indicates whether Gauge 1 is at

the most recently commanded position.

• 0 = At commanded position

• 1 = Not at commanded position

CMD0 (OD10)—This bit indicates whether Gauge 0 is at

the most recently commanded position.

• 0 = At commanded position

• 1 = Not at commanded position

OV (OD9)—Overvoltage Indication. A logic [1] on this bit

indicates VPWR voltage exceeded the upper limit of VPWROV

since the last SPI communication (refer to the Static Electrical

Characteristics table under POWER INPUT, page 5). An

overvoltage event will automatically disable the driver

outputs. Because the pointer may not be in the expected

position, the master may want to re-calibrate the pointer

position with an RTZ command after the voltage returns to a

normal level. For an overvoltage event, both gauges must be

re-enabled as quickly as this flag returns to logic [0]. The

state machine will continue to operate properly as long as

VDD is within the normal range.

• 0 = Normal range

• 1 = Battery voltage exceeded VPWROV

UV (OD8) —Undervoltage Indication. A logic 1] on this bit

indicates the VPWR voltage fell below VPWRUV since the last

SPI communication (refer to the Static Electrical

Characteristics table under POWER INPUT, page 5). An

undervoltage event is just flagged; however, at some voltage

level below 4.0 V, the outputs turn OFF and the state

machine resets. Because the pointer may not be in the

expected position, the master may want to re-calibrate the

pointer position with an RTZ command after the voltage

returns to a normal level. For an undervoltage event, both

gauges may need to be re-enabled as quickly as this flag

returns to logic [0]. The state machine will continue to operate

properly as long as VDD is within the normal range.

• 0 = Normal range

• 1 = Battery voltage fell below VPWRUV

CAL (OD7)—Calibrated Clock out of Specification. A

logic [1] on this bit indicates the clock count calibrated to a

value outside the expected range given the tolerance

specified by tCLC in the Dynamic Electrical Characteristics

D11

D10

x = Don’t care.

Table 15. Device Status Output Register

Bits

OD15

OD14

OD13

OD12

OD11

OD10

OD9

OD8

OD7

OD6

OD5

OD4

OD3

OD2

OD1

OD0

Read

DIR1

DIR0

0POS1 0POS0 CMD1 CMD0

CAL

OVUV MOV1 MOV0

RTZ1

RTZ0

OT1

OT0

Write

–

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