595数码管（595 digital tube）.docVIP

595数码管（595 digital tube） Nineteenth 74HC595 digital tube Nineteenth 74HC595 digital tube To quote the official language: 74HC595 is a silicon CMOS device structure, compatible with low voltage TTL circuit, to comply with the JEDEC standard. In short, it is the function of the 8 bit serial input parallel output shift register is serial to parallel. Below is the package diagram: 74HC595 has two internal registers: 8 bit shift register and a 8 storage register, following PROTEUS under each pin test: You can see the debugging: DS is a serial data input port; SH_CP serial clock input port SH_CP, each rising edge comes, the chip shift register will shift to the left one, the lowest decided by DS, maximum displacement lost time, high has become one of the most high, and reflected in the Q7 (according to Q7can be seen, 74HC595 also has a serial output function); ST_CP will rise each value of the shift register output to a storage register along, storage register is directly connected with the Q0~Q7 pin, so the storage register value will be directly reflected in the pin Q0~Q7 Last, in order to achieve the serial parallel function; OE is the output enable, high level Q0~Q7 for the high resistance state, low level Q0~Q7 storage register value; MR is low, the shift register is 0, the high level is invalid; VCC is connected with a power supply; GND grounding. Well, all the pins finished. Some package diagram pin is not the same name, function is the same. The following two pieces of 74HC595 (U1 and U2) respectively control four digital tube (U1) display and selection (U2), in order to reduce the connection, the two 74HC595 series (U2 Q7output to U1 DS), so U2 DS continuous to write two bytes (the first The number to be displayed, second is selected), we can show. This LPC2103 three port (P0.4 SH_CP, P0.6 even DS, P0.7 even P0.7ST_CP) can operate the four digital tube were overcast (note that it is not the total of yin and Yang, two Between the conversion easy to display digital