AN1043 Просмотр технического описания (PDF) - Microchip Technology

Номер в каталоге

Компоненты Описание

производитель

AN1043

Unique Features of the MCP23X08/17 GPIO Expanders

Microchip Technology 

AN1043

INTERNAL ADDRESS POINTER

CONTROL

Some slave serial devices automatically increment

their internal address pointer after each byte is clocked

by the master. This allows the master to sequentially

access multiple registers without re-sending the write

or read command.

Other slave devices do not automatically increment

their internal address pointer.

The MCP23X08/17 family of devices have the ability to

do either by configuring a control bit (IOCON.SEQOP).

This allows maximum flexibility when accessing the

registers.

For example, when configuring the device, it may be

desirable to allow the address pointer to automatically

increment so the device does not have to be re-

addressed after every byte.

Likewise, when performing a continuous operation on

a register (e.g., changing the outputs on a regular basis

by writing to GPIO or OLAT), it may be beneficial to

disable the address incrementing feature so that the

register is always accessed without re-addressing the

register.

FIGURE 5:

8-BIT MODE: ADDRESS POINTER DISABLED (MCP23008 EXAMPLE)

When the address pointer is DISABLED and the device is in

8-bit mode, the address pointer will not increment the

address pointer.

S 0100aaa0A 00001010A 10101010A 01010101A 10101010P

MCP23X08

Opcode

Register

Addr = 09h

Data @

09h

Data @

09h

Data @

09h

GPIOA

09

OLATA

0A

IODIRB

10

IPOLB

11

GPINTENB 12

DEFVALB 13

INTCONB 14

IOCON

15

GPPUB

16

INTFB

17

INTCAPB 18

GPIOB

19

OLATB

1A

See Figure 5 and Figure 6 for address pointer examples for the

MCP23X08 8-bit devices and Figure 7 and Figure 8 for the

MCP23X17 examples.

© 2006 Microchip Technology Inc.

DS01043A-page 5

Share Link: