Interrupt, power supply & reset STMPE801
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All GPIO registers are named as GPxx, where
Xxx represents the functional group
The function of each bit is shown in the following table:
On power-up reset, all GPIO are set as input.
8.4 Power supply
STMPE801 GPIO operates from a separate supply pin (V
IO
). This dedicated supply pin
provides a level-shifting feature to the STMPE801.
GPIO will remain valid until V
IO
is removed.
The host system may choose to turn off V
CC
supply while keeping V
IO
supplied.
However it is not allowed to turn off supply to V
IO
, while keeping the Vcc supplied.
8.5 Reset
STMPE801 is equipped with an internal POR circuit that holds the device in reset state, until
the V
IO
supply input is valid. The internal POR is tied to the Vio supply pin.
The reset pin allows the host to reset the STMPE801 directly. Minimum pulse width of reset
signal is 100µs.
During the period when reset pin is asserted, all GPIO default to inputs.
Bit 76543210
GPxx IO-7 IO-6 IO-5 IO-4 IO-3 IO-2 IO-1 IO-0
Table 16. Pin function
Register Name Function
GPIO Monitor Pin State Reading this bit yields the current state of the bit. Writing has no effect.
GPIO Set Pin State Writing ‘1’ to this bit causes the corresponding GPIO to go to ‘1’ state.
Writing ‘0’ to this bit causes the corresponding GPIO to go to ‘0’ state.
GPIO Set Pin Direction ‘0’ sets the corresponding GPIO to input state, and ‘1’ sets it to output
state. All bits are ‘0’ on reset.
