#The 8th Lichuang Electronic Competition#Desktop electronic clock

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please fill it out during the registration stage↓
 
* 1. Introduction to project functions
1. R7FA2E1A72DFL is used as the main control chip of the electronic clock
2. A four-digit 0.56-inch common cathode digital tube is used to display the time
3. The ambient temperature is collected through the DHT11 temperature and humidity sensor
4. Four buttons are used for clock setting buttons
5. A reset button, serial port circuit, and SWD download circuit are led out to facilitate download and debugging
6. The Renesas chip integrates a touch pin, and a touch pin is led out to be used as a touch button
7. A passive buzzer is used as a reminder of time reaching, etc.
8. The power switching circuit is composed of AO3401A+1N5819 diodes
9. The battery is charged through TP4056
 
*2. Project attributes
Replicate the official open source electronic clock project, not original Desktop electronic clock design based on the R7FA2E1A72DFL chip to realize clock display and time setting. The DHT11 temperature and humidity sensor is used to collect the ambient temperature and humidity. The reset button, serial port circuit, and SWD download circuit are all led out for easy download and debugging
* 3. Open source agreement
GPL3.0
*4. Hardware part
 1. Power supply circuit
      The power supply circuit is mainly composed of TYPE-C interface and power indicator light. It uses a 2Pin TYPE-C interface, which is simple and convenient and easy to weld. R1 is used as the current limiting resistor of the power indicator light, and LED1 is used as the power indicator light. When the switch is closed, it will light up for prompting.
2.
      Main control circuit The main control microcontroller uses R7FA2E1A72DFL, with an operating voltage between 1.6V and 5.5V, a maximum clock frequency of 48Mhz, and a maximum support of 128-KB FLASH, 16-KB SRAM, and 12-bit AD conversion controller. The chip has an integrated crystal oscillator, which does not require an external crystal oscillator. At the same time, it integrates touch function, and can realize touch function without a touch chip. Add a 100nf capacitor to the power input part for power filtering. The VCL pin is used to stabilize the smoothing capacitor of the internal power supply. This pin needs to be connected to a 4.7uf capacitor to the VSS pin.
3. Reset circuit
      Reset is also called restart. Press the RST button, the RST pin of the main control is pulled low, the system enters the reset state, release the RST button, the RST pin of the main control returns to a high level, the system resumes the working state, and the reset is completed.
4. Boot mode selection circuit
      When the BOOT1 button is not pressed, the BOOT pin is high, the microcontroller enters the Single-chip mode, that is, the normal working mode. When the button is pressed, the BOOT pin is low, and the microcontroller enters the SCI-BOOT mode, that is, the program download mode, so we can use this button to control the microcontroller to download the program or run normally.
5. Touch control circuit
      R7FA2E1A72DFL main control chip has a touch function. Add a 560 ohm damping capacitor and an appropriate capacitor to stabilize the touch signal on the touch line. In fact, it is sensitive and accurate enough.
6. The independent button circuit
      uses four buttons as clock control or other functions.
7. The DHT11 temperature and humidity sensor circuit
      uses the DHT11 temperature and humidity sensor to detect the ambient temperature and humidity. DHT11 is a single bus communication method, and a pull-up resistor needs to be connected to the bus. When the bus is idle, its state is high.
 
8. The passive buzzer drive circuit
      controls the negative pole of the passive buzzer through the NPN transistor. R7 is a current limiting resistor. The function of R8 is to provide a reliable potential when the chip is just powered on or off to prevent interference. The electromagnetic passive buzzer here is an inductive load. The D1 diode is added as a freewheeling diode to prevent burning.
9. The four-digit digital tube drive circuit
      uses a 0.56-inch common cathode digital tube to display time, temperature, humidity and other information.
10. The
      first part of the lithium battery charging and discharging is the power switching circuit. The power switching circuit is composed of a P-channel MOS, a pull-down resistor and a diode. When the TYPE-C interface is connected, 5V comes over, and the voltage of the MOS tube G pole is 5V. After a 1N5819 Schottky diode, the VCC voltage is 4.4V, that is, the S pole is 4.4V, which does not meet the conduction conditions, and the battery power cannot come. When the TYPE-C interface is disconnected, the G pole is pulled down to a low level. Due to the presence of the body diode, the S pole will have a voltage of about 3.5V, which meets the conditions. At this time, the MOS tube is turned on, and the battery will power the subsequent circuit. Due to the presence of the 1N5819 Schottky diode, the current will not flow back in reverse.
The battery is charged through a TP5056 lithium battery charging chip. When the TYPE-C interface is connected, the lithium battery will be charged at the same time to ensure sufficient power. LED2 is used as a charging status indicator, and R11 is a charging current feedback resistor. By changing the resistance value of R11, the overall charging current can be changed.
11. The serial port debugging interface
      leads out the serial port pins through the 2.54*4P interface for serial port download and debugging.
12. The SWD debugging interface
      leads out the SWD pins through the 2.54*4P interface for SWD mode download and debugging.
 
*5. The software part
is a replica of the official open source product, and the code is provided by Renesas Xiaogong
 
*6. BOM list
*7. Competition LOGO verification
 
* 8. Demonstrate your project and record it into a video for upload
 
. Please see the attachment: Demonstration video