ST STM8S Reference Manual

RM0016 General purpose I/O ports (GPIO)
Doc ID 14587 Rev 8 109/449
11.7.2 Interrupt capability
Each I/O can be configured as an input with interrupt capability by setting the CR2x bit while
the I/O is in input mode. In this configuration, a signal edge or level input on the I/O
generates an interrupt request.
Falling or rising edge sensitivity is programmed independently for each interrupt vector in
the EXTI_CR[2:1] registers.
External interrupt capability is only available if the port is configured in input mode.
Interrupt masking
Interrupts can be enabled/disabled individually by programming the corresponding bit in the
configuration register (Px_CR2). At reset state, the interrupts are disabled.
If a pin alternate function is TLI, use the Px_CR2 bit to enable/disable the TLI interrupt. The
TLI interrupt is associated to a dedicated interrupt vector.
11.7.3 Analog channels
Analog I/O channels can be selected by the ADC peripheral. The corresponding input and
output stages are then automatically disabled. As mentioned in the next section, the input
Schmitt trigger should be disabled in the ADC_TDR register when using the analog
channels.
11.7.4 Schmitt trigger
An internal input Schmitt trigger is included in some I/Os. The Schmitt trigger can be
enabled/disabled using the ADC_TDR Schmitt trigger disable register.
11.8 Output mode details
11.8.1 Alternate function output
Alternate function outputs provide a direct path from a peripheral to an output or to an I/O
pad, taking precedence over the port bit in the data output latch register (Px_ODR) and
forcing the Px_DDR corresponding bit to 1.
Table 23. Recommended and non-recommended configurations for analog input
DDR CR1 CR2 ADC_TDR Configuration Comments
00 0 1
Floating Input without interrupt,
Schmitt trigger disabled
Recommended analog input
configuration
0 1 x x Input with pull-up enabled Not recommended for analog input when
analog voltage is present since these
configurations cause excess current flow
on the input pin.
Both input and output stages are
disabled on ADC selected channel.
1 0 x x Output
1 1 x x Output

ST STM8S Specifications

General

Brand	ST
Model	STM8S
Category	Microcontrollers
Language	English