33784_09 datasheet(21/30 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33784

FUNCTIONAL DEVICE OPERATION

LOGIC COMMANDS AND REGISTERS

Figure 13. Request AN1 Command and Response Format

I/O CONTROL COMMAND AND RESPONSE

This command can be used to configure the direction of

the I/O pins, and force their states if configured as outputs.

Refer to Figure 14 for the command and response format.

The response is sent during the next message following a

valid I/O Control command to the addressed device. Because

this is a long-word only command, there is no short word

response.

The direction (DR) bits are used to specify the direction

(input or output) of each pin independently. If the DR bit for a

specific I/O pin is set to 1, then that I/O pin will be an output

and the state of the level (Lx) bit will determine whether the

pin is driven high or low. If the DR bit for a specific I/O pin is

set to 0, then that pin will be an input and the Lx bit in the

command will have no affect on the state of the pin.

In the response to the I/O Control Command, the DR bits

will show the direction that the pins were programmed. The

Lx bits will have the values that were set in the command.

These values may not reflect the actual states of the pins. To

obtain the accurate states of the pins, the Request Status

Command should be used.

The 33784 will only act on the I/O Control Command if the

address bits in the command match with the address that the

device was initialized. If the addresses do not match, the

device will do nothing and no response will be generated.

Address ‘0000’ is a global command. All slaves in the

signal path will configure their I/O pins according to the state

of the data bits. No response results from the I/O control

global command.

Data

Address

Command

Word Type

––––––––

0101

LW & ELW

0101

SW & ESW (8-bit)

––

0101

ESW (10-bit)

Response

Word Type

0000

LW & ELW

SW & ESW (8-bit)

ESW (10-bit)

Legend

A[3:0] = Address bits. The address of the selected device.

An address value of 0000 is ignored by all devices.

“–” = Don’t care bit. Can be 0 or 1.

B[9:0] = Measured value.

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