© 2006 Microchip Technology Inc.

DS22003B-page 11

MCP3421

5.2

Configuration Register

The MCP3421 has an 8-bit wide configuration register

to select for: PGA gain, conversion rate, and conver-

sion mode. This register allows the user to change the

operating condition of the device and check the status

of the device operation. The user can rewrite the

configuration byte any time during the device

operation. Register 5-1 shows the configuration

register bits.

REGISTER 5-1:

CONFIGURATION REGISTER

R/W-1

R/W-0

R/W-0

R/W-1

R/W-0

R/W-0

R/W-0

R/W-0

RDY

C1

C0

O/C

S1

S0

G1

G0

1 *

0 *

0 *

1 *

0 *

0 *

0 *

0 *

bit 7

bit 0

* Default Configuration after Power-On Reset

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

RDY: Ready Bit

This bit is the data ready flag. In read mode, this bit indicates if the output register has been updated

with a new conversion. In One-Shot Conversion mode, writing this bit to “1” initiates a new conversion.

Reading RDY bit with the read command:

1 = Output register has not been updated.

0 = Output register has been updated with the latest conversion data.

Writing RDY bit with the write command:

Continuous Conversion mode: No effect

One-Shot Conversion mode:

1 = Initiate a new conversion.

0 = No effect.

bit 6-5

C1-C0: Channel Selection Bits

These are the Channel Selection bits, but not used in the MCP3421 device.

bit 4

O/C: Conversion Mode Bit

1 = Continuous Conversion Mode. Once this bit is selected, the device performs data conversions

continuously.

0 = One-Shot Conversion Mode. The device performs a single conversion and enters a low power

standby mode until it receives another write/read command.

bit 3-2

S1-S0: Sample Rate Selection Bit

00 =

240 SPS (12 bits),

01 =

60 SPS (14 bits),

10 =

15 SPS (16 bits),

11 =

3.75 SPS (18 bits)

bit 1-0

G1-G0: PGA Gain Selector Bits

00 =

1 V/V,

01 =

2 V/V,

10 =

4 V/V,

11 =

8 V/V