Using a STMPE801 (I²C bus) 8-bit I/O port expander

AN2591

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you must configure the INTPolarity bit and the INT_Enable bit in the SystemControl register

(address = 0x04).

You must read the ISGPIOR register in interrupt routine to determine which GPIO has

generated the interrupt. Each bit of this register, represents the interrupt status of each

GPIO pin.

The VIO pin is provided to fix the voltage used by the GPIOs. The VIO pin level, must be

greater than or equal to the Vcc level.

The RESET input pin is connected to any microcontroller GPIO to initialize the STMPE801

when it is needed.

3.2

16 additional input/output lines.

Figure 10 shows how two STMPE801 share the two lines of the I2C interface with different

addresses. The first device the has its ADDR0 input connected to ground will have the

address 0x82, whereas the ADDR0 input of the second device is connected to Vcc to fix the

I2C device address to 0x88.

It is possible to use the two interrupt outputs of the two devices to expand the interrupt lines

to 16. Each interrupt output (INT: pin 11) is connected to an interrupt input (two interrupt

inputs are used, see Figure 10).

Note:

When only one interrupt is available in the microcontroller you are using, you can add an

appropriate logic gate to connect the two INT outputs to its inputs and connect the gate

output to the interrupt input of the microcontroller. In this case, to determine which GPIO has

generated the interrupt, you must read the ISGPIOR register of each device).