MCP3421

DS22003B-page 16

© 2006 Microchip Technology Inc.

FIGURE 5-4:

Timing Diagram For Writing To The MCP3421.

5.4

General Call

The MCP3421 acknowledges the general call address

(0x00 in the first byte). The meaning of the general call

address is always specified in the second byte. Refer

to Figure 5-5. The MCP3421 supports the following

general calls:

5.4.1

GENERAL CALL RESET

The general call reset occurs if the second byte is

‘00000110’ (06h). At the acknowledgement of this

byte, the device will abort current conversion and

perform an internal reset similar to a power-on-reset

(POR).

5.4.2

GENERAL CALL CONVERSION

The general call conversion occurs if the second byte

is ‘00001000’ (08h). All devices on the bus initiate a

conversion simultaneously. For the MCP3421 device,

the configuration will be set to the One-Shot Conver-

sion mode and a single conversion will be performed.

The PGA and data rate settings are unchanged with

this general call.

FIGURE 5-5:

General Call Address

Format.

9

1

9

1

Stop Bit by

11

0

1A2 A1 A0

R/W

ACK by

MCP3421

RDY

C1 C0

O/C

S1 S0 G1 G0

1st Byte:

2nd Byte:

Master

ACK by

MCP3421

MCP3421 Address Byte

Configuration Byte

Start Bit by

Master

with Write command

Note:

– Stop bit can be issued any time during writing.

– MCP3421 device code is 1101.

– Address Bits A2- A0 = 000 are programmed at factory unless customer requests different codes.

SCL

SDA

Note:

“00000000” (00h) in the second byte.

LSB

First Byte

ACK

x

0 0 0 0 0 0 0 0 A

A

xx x x x x x

(General Call Address)

Second Byte

ACK