Rainbow-electronics MAX7311 Bedienungsanleitung PDF herunterladen (Seite 11)

Output Port Registers

The output port registers (Table 3) set the outgoing

logic levels of the I/Os defined as outputs by the

respective configuration register. Reads from the out-

put port registers reflect the value that is in the flip-flop

controlling the output selection, not the actual I/O value.

Polarity Inversion Registers

The polarity inversion registers (Table 4) enable polarity

inversion of pins defined as inputs by the respective

port configuration registers. Set the bit in the polarity

inversion register to invert the corresponding port pin’s

polarity. Clear the bit in the polarity inversion register to

retain the corresponding port pin’s original polarity.

Configuration Registers

The configuration registers (Table 5) configure the

directions of the I/O pins. Set the bit in the respective

configuration register to enable the corresponding port

as an input. Clear the bit in the configuration register to

enable the corresponding port as an output.

Bus Timeout

Set register 0x08 LSB (bit 0) to enable the bus timeout

function (Table 6) or clear it to disable the bus timeout

function. Enabling the timeout feature resets the

MAX7311 serial bus interface when SCL stops either high

or low during a read or write. If either SCL or SDA is low

for more than 29ms after the start of a valid serial transfer,

the interface resets itself and sets up SDA as an input.

The MAX7311 then waits for another START condition.

Standby

The MAX7311 goes into standby when the I

C bus is

idle. Standby supply current is typically 2.9µA.

Applications Information

Power-Supply Consideration

The MAX7311 operates from a supply voltage of 2V to

5.5V. Bypass the power supply to GND with a 0.047µF

capacitor as close to the device as possible.

MAX7311

2-Wire-Interfaced 16-Bit I/O Port Expander

with Interrupt

______________________________________________________________________________________ 11

I7 I6 I5 I4 I3 I2 I1 I0

BIT

I15 I14 I13 I12 I11 I10 I9 I8

Table 2. Registers 0x00, 0x01—Input Port Registers

O7 O6 O5 O4 O3 O2 O1 O0

BIT

O15 O14 O13 O12 O11 O10 O9 O8

Power-up default 1 1111111

Table 3. Registers 0x02, 0x03—Output Port Registers

I/O7 I/O6 I/O5 I/O4 I/O3 I/O2 I/O1 I/O0

BIT

I/O15 I/O14 I/O13 I/O12 I/O11 I/O10 I/O9 I/O8

Power-up default 0 0000000

Table 4. Registers 0x04, 0x05—Polarity Inversion Registers

I/O7 I/O6 I/O5 I/O4 I/O3 I/O2 I/O1 I/O0

BIT

I/O15 I/O14 I/O13 I/O12 I/O11 I/O10 I/O9 I/O8

Power-up default 1 1 1 1 1 1 1 1

Table 5. Registers 0x06, 0x07—Configuration Registers

BIT 76543210

Power-up default 00000001

Table 6. Register 0x08—Timeout Register

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 17

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