Make essential functions more engaging with 3006.2117 and STM32F091RC

Button Y Click is based on the 3006.2111, a high-quality, single-pole, single-throw (SPST) tactile switch from Marquardt. This is a high-quality, low-profile pushbutton with a reasonably large diameter of 6.8mm. It is equipped with a yellow LED, which can be dimmed by applying a PWM signal from the MCU. Therefore, the anode of the LED is connected to the PWM pin of the mikroBUS™. The embedded LED can be used for a signalization, but also for aesthetic purposes. The switch itself has very good characteristics: it has a low ON resistance (a resistance through the button while it is pressed) of less than 100mΩ, very low bouncing time (a time during which the contact plates settle down) of less than 1.5ms typically. The mechanical endurance of the tactile switch is rated to more than 500,000 cycles, while applying 14VDC, 10mA. The total travel distance of the button is 2.9 mm, while the tactile force of the button is 4N. The maximum voltage that should be used between the switch terminals is 28V, while the current should stay below 50mA. Two important properties that describe a button, are its mechanical endurance and bouncing delay. Those two attributes depend on each other, so

when a significant bouncing appears, it might be a sign of a switch deterioration. Likewise, a switch will develop larger bouncing effect as it is been used over time. The mechanical endurance is also affected by the force applied to the switch while operated, as well as its eccentricity (pressing the button off center). Bouncing time is a parameter which describes how fast contact plates of a switch are settled down. Each material has some elastic properties. This is also true for the contact plates of the button. Different types of switches have different mechanism to establish a contact, but they are all based on a common principle: they are made so they accumulate the pressure force, until there is enough energy stored so that the plate can be actuated very fast, turning the accumulated pressure into kinetic energy (resulting with the familiar click sound). The most often, a form of spring mechanism is used. However, when hitting the second, fixed plate, a moving plate will bounce off a few times, depending on the elasticity of the system, its speed and so on. There is no ideal dampening mechanism to reduce the bouncing completely. This button will accumulate force up to about 1N

before its actuated, providing a tactile feedback while clicking. The tactile switch used on Button Y click has an excellent bouncing duration of less than 1ms. However small, the bouncing of a button needs to be compensated, either in the application firmware, or the hardware. Button Y click has a simple debouncing circuit, made of a 10kΩ resistor and 10nF capacitor, which is sufficient for the most cases. The debounced signal will have a small delay, depending on a dampening circuitry. The delay is in the range of a few milliseconds, which is far less than a human can sense. Finally, the button is intended to be operated by a human, so even much larger delay is perfectly acceptable for this type of device. The button is active HIGH, which means that when it is pressed, a HIGH logic level will be applied to the INT pin. This switch will be pulled to a LOW logic level by the 10kΩ pull-down resistor while inactive, preventing the input pin of the MCU to become floating. The switch signal is routed to the INT pin of the mikroBUS™. An onboard SMD jumper labeled as VCC SEL is used to set the voltage for the HIGH logic level, allowing the Button Y click to be used with a wide range of different MCUs.

Nucleo-64 with STM32F091RC MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin

headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is

provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.