|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| ||||

|||||||||||||||||

2015-07-0044

PT0559

08/05/15

8

PI4IOE5V9570

4-bit general purpose outputs

for 1MHz I

e. Bus Transaction

Writing to the port (output mode)

To write, the master (microcontroller) first addresses the slave device. By setting the last bit of the byte containing the slave

address to logic 0, the Write mode is entered. The device acknowledges and the master sends the data byte for P7 to P0 and is

acknowledged by the device. Writes to P7 to P4 are ignored in the PI4IOE5V9570 as only P3 through P0 are available. The 4-bit

data is presented on the port lines after it has been acknowledged by the device. The number of data bytes that can be sent

successively is not limited. The previous data is overwritten every time a data byte has been sent.

Reading from a port (input mode)

All ports are outputs and cannot be used as inputs. When reading the device, the data returned is the port state at the pin. To read,

the master (microcontroller) first addresses the slave device by setting the last bit of the byte containing the slave address to logic

1. The data byte that follows on the SDA is the value of the ports pins. There is no limit to the number of bytes read, and the state

of the output port pins is updated at each acknowledge cycle. Logic 1 means that the port is HIGH. Logic 0 means that the port is

LOW. When the PI4IOE5V9570 is read, P7 through P4 return logic ‘1’.

f. Power-on reset

When power is applied to VCC, an internal Power-On Reset (POR) holds the device in a reset condition until VCC has reached

VPOR. At that point, the reset condition is released and the device registers and I

default states.

Figure 6: Write to configuration registers

Figure 7: Read from registers

Note: Transfer can be stopped at any time by a STOP condition.