The hardware circuit design
Wireless remote control launch section
Circuit shown in figure 3, emission components adopt F06A module of the encoder, its transmission frequency stability at 315 MHZ, for 3 ~ 12 v voltage range, transmission power for 10 mw. The system adopts two pieces of 3 v button battery, can work for more than six months. The module has eight / 3 state address code, used to identify one to one correspondence of transmitting and receiving device, in case of other influences of remote control electric misoperation. When installing the module, the first eight address coding end properly connected (code), such as the no. 1, 2 for high level address, the address code is 11000000. There are four data pins D1, D2, D3, D4, four data end connection button respectively in the design of the S1, S2, S3, S4, S1 to switch function keys, S2 to adjust the "add" button, the S3 adjustment "reduced" button, S4 for confirmation key. Two buttons at the same time extend the S5 and S6, as open display and disable display keys, respectively. LED lights for buttons, S7 for remote control part of the power switch. The module is normal launch distance of 10 m, if plus a 24 cm long single antenna, farther.
Remote control receiving part
Remote control receiving part as shown in figure 4, use with F06A J06A receiving module, the module of working voltage is 2.6 ~ 3.6 V, receiving sensitivity to 5 mu V, eight address on its side, when using the connection must be consistent with the module of address coding. The module receive frequency is 315 MHZ, it will receive the remote signal by the internal demodulation, decoding, reduction for certainly the same password signal transmitter, and all the way from its four data output for monolithic P1.0 ~ P1.3 mouth, another path isolation diodes D7 ~ D10, controlled triode Q8 conduction, so that SCM INTO the interrupt, single-chip microcomputer, the information of P1.0 ~ P1.3 after compared with the original set of information, to perform the corresponding operation.
DS3231 real-time clock chip
DS3231 is a low cost, high precision, real time clock chip (RTC), on chip integrates high stability crystal vibration, temperature compensation circuits, within the range - 40 ℃ ~ + 85 ℃ provides the clock precision of + / - 2 min each year. Compared with other schemes based on the crystal, DS3231 in time accuracy of temperature range increased five times. RTC provided seconds, minute, hour, day, week, month and year, such as information, with a leap year correction, and itself with battery, without external power supply can work for 10 years. Also provide two programmable alarm clock and programmable square-wave output, I2C bidirectional data bus transmission. Encapsulation using 16 feet.
24 c08 is 8 KB does not have encryption function electrically erasable PROM, compatible with second-line agreement I2C bus, with 8 feet encapsulation, small volume, low power consumption, easy to use, storage structure is simple, only two operating functions, speaking, reading and writing, here are used to store information about remote control code and clock chip information.
The LED driver circuit
Display driver part adopts MBI5001 integration chip, it has both the functions of displacement function and latches for string into and out of the eight registers. Specific control mode for the first piece of MBI5001 SDI input end is connected to the MCU serial data output terminal of the SDO data output end is connected to the next piece of SDI, each piece of cascade all use the same way. Each piece of corresponding CLK, LE, OE side respectively in parallel, as uniform data shift signal and serial data into and latches latch signal output data signal connection.
6 choose AT89S52 MCU, its external crystal vibration frequency of 12 MHZ. USES the LED digital dot matrix display, the design assumption to show the four characters (according to actual needs design shows the number of characters). SCM P2.4 port with the first disc shows drive data input terminal connected to SDI, serial data communication, P2.3, P2.2 respectively meet all MBI5001 common clock pulse input port and move into the latch signal input port, P2.1 used as the output latch signal input port. Buzzer P1.0 port, when the query to the song has a remote control signal input. Real time clock DS3231 and EEPROM24C08 support bidirectional I2C bus and data transfer protocol, P3.0, P3.1 mouth of SCL and SDA input respectively, through the I2C bus for data exchange between and CPU.
The software design
Stack, the main function of the main program includes: set a timer and serial port initialization, set the parameters of interruption, and initialize some registers and flags, they needed to complete the keyboard monitoring function, so that when there is a button press, perform the corresponding operation; When there is no answer the key press, read DS3231 clock data and data processing, such as the clock data to the display buffer, finally also will display buffer data to the serial display. As shown in figure 5.