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We have already seen an Easy Method to Control one 74HC595 / 74HCT595 using Arduino Mega. Here we will see the cascade operation of two 74HC595 / 74HCT595 using Arduino mega. By 74595, we can easily control eight LEDs using three digital pins of arduino. If two 74595 are connected in cascade, sixteen LEDs can be controlled using three digital pins of arduino. Similarly, if three 74595 are connected in cascade, twenty four LEDs can be controlled using three digital pins of arduino. Connections are done as shown in the following diagram. If the circuit is not clear, download the circuit (right click on circuit => Save Image As) to your computer and open in a suitable image viewer.
Pinout diagram of 74HC595 / 74HCT595 is given below.
DS pin of 1st 74595 is connected to the 13th digital pin of arduino. In cascade operation of 74595, Q7' (Pin 9) of 1st 74595 is connected to the DS (Pin 14) of 2nd 74595. SHCP (Pin 11) of both 74595 are connected to the 12th digital pin of arduino. Similarly STCP (Pin 12) of both 74595 are connected to the 11th digital pin of arduino. Q0 - Q7 pins of both 74595 are connected to individual LEDs as shown in the circuit. Current limiting resistances of 1K should be connected in series with these LEDs. 5V for the operation of 74595 is given from a 5V voltage regulator. Read about arduino programs for cascade operation of 74595 in next page.
Pinout diagram of 74HC595 / 74HCT595 is given below.
DS pin of 1st 74595 is connected to the 13th digital pin of arduino. In cascade operation of 74595, Q7' (Pin 9) of 1st 74595 is connected to the DS (Pin 14) of 2nd 74595. SHCP (Pin 11) of both 74595 are connected to the 12th digital pin of arduino. Similarly STCP (Pin 12) of both 74595 are connected to the 11th digital pin of arduino. Q0 - Q7 pins of both 74595 are connected to individual LEDs as shown in the circuit. Current limiting resistances of 1K should be connected in series with these LEDs. 5V for the operation of 74595 is given from a 5V voltage regulator. Read about arduino programs for cascade operation of 74595 in next page.
Next: Program to Demonstrate Cascade Operation of 74595 |
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