View source for Lesson 12--Microduino 74HC595 Cascade and Serial input Parallel ouput Data

{{Language|第十二课--Microduino 74HC595级联数据串入并出}}
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==Objective==
This tutorial will teach you how to use Microduino to control 74HC595 and display a binary number using 8 LEDs.

==Equipment==
*'''[[Microduino-Core]]'''
*'''[[Microduino-FT232R]]'''
*Other equipment:
**Breadboard Jumper            one box   
**Breadboard  	               one piece  
**LED                          eight
**74HC595 chip                 one 
**220Ω                         eight
**1μF capacitor                one
**USB cable                    one

'''74HC595'''
[[File:第十二课-74HC595.jpg|600px|center|thumb]]

74HC595 has eight output pin Q0~Q7 uses to output binary number, mostly use to convert the decimal number to binary number.

74HC595 is the silicon CMOS devices, compatible with low voltage TTL circuit, abide by the JEDEC standard. 74HC595 has a 8 bits shift register and a memory and with three-state output function.

Shift register and memory's clock is respectively. Data was input to the shift register at the rising edge of SHcp (the shift register clock input), then input to the storage register (memory) at the rising edge of STcp.

If the two clocks connect together, the shift register is always earlier a pulse than the storage register. Shift register has a  serial shift input (Ds), a serial output (Q7')  and a low level of asynchronous reset. Storage registor has a parallel, three-state bus output. When enabled OE (low level), storage register's data output to the bus.

Eight bits serial input/output or parallel output shift register has high resistance off state and three-state function.

Turn the serial input 8 digits serial input to parallel output, such as controlling an 8-bit digital tube, there will be no flicker.

==Schematic==
[[File:第十二课-Microduino 74HC595数据传入并出原理图.jpg|600px|center|thumb]]

==Program==
Download program:
https://github.com/Microduino/Microduino_Tutorials/tree/master/Microduino_Advanced/Microduino_74HC595

<source lang="cpp">

/*                               
Use the 74HC595 shift register to count from 0 to 255
*/

//Pin 8 connects to 74HC595's ST_CP
int latchPin = 8;
//Pin 12 connects to 74HC595's SH_CP
int clockPin = 12;
////Pin 11 connects to 74HC595's DS
int dataPin = 11;



void setup() {
  //Set pins as output 
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
}

void loop() {
    //Display binary number in LED, from 0 to 255
  for (int numberToDisplay = 0; numberToDisplay < 256; numberToDisplay++) {
    //Set latchPin as low leverl 
    digitalWrite(latchPin, LOW);
    //Output decimal number
    shiftOut(dataPin, clockPin, MSBFIRST, numberToDisplay);  

    //Set latch pin as high level, LED will display conrresponding binary nmuber
    digitalWrite(latchPin, HIGH);
    // pause before next value:
    delay(500);
  }
}


</source>


Function description：

shiftOut(dataPin, clockPin, bitOrder, value) 

dataPin: dataPin's pin number

clockPin: clockPin's pin number

bitOrder: Ordered binary code, MSBFIRST(The most significant bit first) or LSBFIRST(The least significant bit first)

value: the converted decimal number

==Debug==
Step 1: Cope the code to IDE and compile it

Step 2: Set up circuit, as follows:

[[File:第十二课-Microduino 74HC595数据串入并出连接图1.jpg|600px|center|thumb]]

[[File:第十二课-Microduino 74HC595数据串入并出连接图2.jpg|600px|center|thumb]]

Step 3: Run program

Step 4: Observe LED

==Result==

8 LEDs will display binary number from 0 to 255. On is 1 and off is 0.

==Video==

http://v.youku.com/v_show/id_XNjgyNTk2MzUy.html