STM32W108CBU6 STMICROELECTRONICS [STMicroelectronics], STM32W108CBU6 Datasheet - Page 51

• Manufacturer Part Number: STM32W108CBU6
• Description: High-performance, IEEE 802.15.4 wireless system-on-chip
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

STM32W108CB, STM32W108HB
Note:
6.1.7
6.2
When configured in alternate output mode:
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Depending on configuration and usage, GPIO_PxOUT and GPIO_PxIN may not have the
same value.
Alternate output SPI SCLK mode
SPI master mode SCLK outputs, PB3 (SC1SCLK) or PA2 (SC2SCLK), use a special output
push-pull mode reserved for those signals. Otherwise this mode is identical to alternate
output mode.
Wake monitoring
The GPIO_PxWAKE registers specify which GPIOs are monitored to wake the processor. If
a GPIO's wake enable bit is set in GPIO_PxWAKE, then a change in the logic value of that
GPIO causes the STM32W108 to wake from deep sleep. The logic values of all GPIOs are
captured by hardware upon entering sleep. If any GPIO's logic value changes while in sleep
and that GPIO's GPIO_PxWAKE bit is set, then the STM32W108 will wake from deep sleep.
(There is no mechanism for selecting a specific rising-edge, falling-edge, or level on a GPIO:
any change in logic value triggers a wake event.) Hardware records the fact that GPIO
activity caused a wake event, but not which specific GPIO was responsible. Instead,
software should read the state of the GPIOs on waking to determine the cause of the event.
The register GPIO_WAKEFILT contains bits to enable digital filtering of the external wakeup
event sources: the GPIO pins, SC1 activity, SC2 activity, and IRQD. The digital filter
operates by taking samples based on the (nominal) 10 kHz RC oscillator. If three samples in
a row all have the same logic value, and this sampled logic value is different from the logic
value seen upon entering sleep, the filter outputs a wakeup event.
In order to use GPIO pins to wake the STM32W108 from deep sleep, the GPIO_WAKE bit in
the WAKE_SEL register must be set. Waking up from GPIO activity does not work with pins
configured for analog mode since the digital logic input is always set to 1 when in analog
mode. Refer to
power management and sleep modes.
External interrupts
The STM32W108 can use up to four external interrupt sources (IRQA, IRQB, IRQC, and
IRQD), each with its own top level NVIC interrupt vector. Since these external interrupt
sources connect to the standard GPIO input path, an external interrupt pin may
simultaneously be used by a peripheral device or even configured as an output. Analog
mode is the only GPIO configuration that is not compatible with using a pin as an external
interrupt.
The output drivers are enabled and are controlled by the output of an on-chip
peripheral:
In open-drain mode: 0 activates the N-MOS current sink; 1 tri-states the pin.
In push-pull mode: 0 activates the N-MOS current sink; 1 activates the P-MOS current
source.
The internal pull-up and pull-down resistors are disabled.
The Schmitt trigger input is connected to the pin.
Reading GPIO_PxIN returns the input to the pin.
Section 5: System modules on page 33
Doc ID 16252 Rev 2
for information on the STM32W108's
General-purpose input/outputs
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