REV. 0

–16–

AD7738

Channel Status Registers

8 Bits, Read-Only Register, Address 20h–27h, Default Value 20h

Channel Number

These registers contain individual channel status information and some general AD7738 status information. Reading the Status

registers can be associated with reading the Data registers in the Dump mode. Reading the Status registers is always associated with

reading the Data registers in the Continuous Read mode. See the Digital Interface Description section for more details.

Bit

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Mnemonic

CH2

CH1

CH0

0/P0

RDY/P1

NOREF

SIGN

OVR

Default

Channel Number

0

0

0

0

0

Bit

Mnemonic

Description

7–5

CH2–CH0

These bits reflect the channel number. This can be used for current channel identification and easier

operation in the Dump mode and Continuous Read mode.

40/P0

When the Status Option bit in the corresponding Channel Setup register is reset to 0, this bit is read

as a zero. When the Status Option bit in set to 1, this bit reflects the state of the P0 output pin.

3

RDY/P1

When the Status Option bit in the corresponding Channel Setup register is reset to 0, this bit reflects the

selected channel RDY bit in the ADC Status register. When the Status Option bit is set to 1, this

bit reflects the state of the P1 pin whether it is configured as an input or output.

2

NOREF

This bit indicates the reference input status. If the voltage between the REFIN+ and REFIN– pins is less

than the NOREF trigger voltage, then the NOREF bit goes to a 1.

1

SIGN

The voltage polarity at the analog input. Will be 0 for a positive voltage; will be 1 for a negative voltage.

0

OVR

This bit reflects either overrange or underrange on an analog input. The bit is set to 1 when the analog

input voltage goes over or under the Nominal Voltage Range. See the Analog Inputs Extended Voltage

Range section.