Touch self-locking switch circuit introduction and switch machine delay processing
The light-touch self-locking switch circuit has been widely used in digital products such as telephones, mobile phones, and electronic dictionaries, and its implementation methods are various. Generally, RS flip-flops, counters, and 555 integrated circuits can be used. In some practical applications of electric toys, the above implementation will increase the complexity of the entire circuit, and can not achieve a simple and practical effect.
This article will introduce a variety of digital products that can be widely used in telephones, mobile phones, and electronic dictionaries in electric toy circuits. Generally, RS flip-flops, counters, and 555 integrated circuits can be used. In some practical applications of electric toys, the above implementation will increase the complexity of the entire circuit, and can not achieve a simple and practical effect. This article will introduce a simple and stable light touch single-button switch circuit that can be implemented in single-chip applications.
A simple, stable, light-touch, single-button switch circuit implemented in the application. It is easy to see that the processing of the Vin connection mode is such that after using this control method, Q1 will consume a certain amount of power. One way to reduce power consumption is to connect Vin directly to the battery, which can be flexibly controlled according to the circuit. 2 Function of Capacitor C1 For general electric toys, there are BOD (Brown-down Detection) circuits inside. This circuit has a low voltage detection function: when the input voltage changes from high to low, the electric toy will automatically reset. When you want to shut down, press S1 and the electric toy output is low. After the button is raised, Q1 and Q2 are cut off, and the MCU is powered off. However, when the BOD circuit of the MCU detects that the voltage of the MCU suddenly drops, it will reset the MCU and set the I/O to the pull-up state. Q1 and Q2 are turned on, and the guiding circuit is turned on again. 3 circuit principle DC socket is a DC stabilized power supply chip with relevant off-control terminal, MCU is a single-chip microcomputer. Tap the self-locking switch to supply
When S1 is pressed, Q1 and D1 are turned on, and the voltage regulator chip works to supply power to the microcontroller. The electric toy immediately sets the corresponding I/O pin to the output high. At this time, Q1 and Q2 are turned on, and the whole circuit enters the working state. The MCU then sets this I/O pin as an input. Q1 and Q2 are always on due to the presence of the pull-up resistor R4. The electric toy always scans the corresponding I/O input status. If S1 is not pressed, the I/O will always be high. When S1 is pressed again, D2 is turned on, and the electric toy detects that the I/O pin input is low. At this time, the electric toy sets the I/O to the output low state. Q2 cutoff, if the button is raised, Q1 will also be cut off, the voltage regulator chip will not provide voltage for the electric toy, and the whole circuit is in the off state.
The values of R3 and pull-up resistor R4 are found in some electric toys, such as the AVR series of electric toy linkage series, with an internal pull-up resistor Rpu. The electric toy program can be used to control whether the resistor is pulled up or not, so that no external pull-up is required.
Under normal circumstances, the value of R3 is much larger than R4, otherwise the input voltage Vpin of the electric toy I/O may be lower than the minimum value of the standard input voltage VIH. From the linkage series toy data sheet, it is found that the value of Rpu is between 20kΩ and 100kΩ, and because the minimum value of VIH is about 0.6VCC. Therefore, R3/(R3+R4)>0.6, take R4=50kΩ, and take R3/(R3+R4)=0.8, so the value of R3 should be in the range of about 200kΩ, and the specific R4 can be selected according to the actual working conditions. value.
Tap the self-locking switch to delay processing. In some specific applications, such as mobile phones and other digital products, the switch machine needs to operate in a delayed manner. A simple implementation is that the microcontroller starts counting when the button is pressed until the button is raised. Only this count is large enough to be allowed.
Due to its small size, multi-gear position, and good driving force, it has been widely used in many fields such as household appliances. With the continuous improvement of people's living standards, the upgrading of these household appliances is getting faster and faster, and the number of them needs to be larger and larger. This is also the biggest potential direction for us to be optimistic about its development prospects.
