The seven segment series is a series that serves to control the 7 segment display. Seven segment itself is basically a combination of several LEDs that form a digital number pattern. To turn seven segment in accordance with the desired number then it takes a series of seven segment drivers. The seven segment driver series is actually optional, can be used can not. If not using 7 segment driver circuit, 7 segment connection can be directly connected with microcontroller controller. A series of seven segment drivers is required if the display used is large enough, so the voltage required to power 7 segments is also large. For such cases a 7 segment driver is required as an intermediary between the microcontroller with 7 segments.
There are so many types of seven segment series that you can use. You can find references in google about this segment 7 segment driver. On this occasion I will discuss one of a series of seven segment using TTL IC type 74HC595. This IC is an IC shift register, its function is to change the input in the form of serial data into parallel data which will be connected to 7 segment display. But this series you can develop for drivers more than 4 digits once you understand the working principle.
IC 74HC595 has some input and output pins. The input consists of the following pins:
- SH_CP, is the clock input pin
- DS, is the input pin of serial data
- ST_CP, is the data latch pin
- MR, is the clear pin output. If this pin is low then the output will be all 0
- OE, Output Enable pin that serves to enable output
While the output of IC 74HC595 consists of pins Q0-Q7 and Q7 '. Pin Q0 - Q7 is a parallel data output that is inserted serially from the DS pin. While pin Q7 'is a serial output that can be connected with other IC 74HC595, as seen in the picture above 7 segment above.
Serial data inputted through the DS pin, every 1 bit of data must be accompanied by 1 cycle clock. The serial data entered as much as 32 bits, because the above circuit there are 4 pieces IC74HC595 where 1 piece of IC has 8 bits of output data. After 32 bits of data entered, to output the output in parallel concurrently pin ST_CP must be set high then low.
The seven segment series is quite simple and cheap to make. There is one more 7 segment driver circuit that uses IC MAX7219. The principle works more or less the same as IC74HC595.