The principle about the Keypad We must first know whether the Keypad we use is either 4 * or 3 * 4, and is analog or digital dial Pull up or Pull down so that it is easy to khiyon the Keypad driver implemented this is 4 * 4 digital PIN so you will be using is connected to the microcontroller, all 8 PIN by PIN1-PIN4 (Column) are used as Input into the Board so that the micro-micro-code reading key is pressed PIN 8 PIN part 5-(ROW). Use the Output from the micro-micro-logic boards, so send. The "0" key is scanned in each row that microchip to read each key logic State principle enters PIN 1-4 PIN. If there is no key to read logic. "1." If the key is pressed, the key in the read logic "0" but before reading the value of each digit must be micro-logic, a logic "0" rows of keys, each row (PIN5-PIN8) to read logic once, but always.
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