ecet_340_quiz_1 - 1(TCO 1 In a typical keypad switch...

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1. (TCO 1) In a typical keypad switch, bouncing occurs for how long? (Points : 5) 5 to 20 ns 5 to 20 μs 5 to 20 ms 5 to 20 s Question 2. 2. (TCO 1) The following command will blank the LCD display. (Points : 5) data = 0x0C, CSB = 0, E = ↓, RS = 1, R/W~ = 0 data = 0x20, CSB = 0, E = ↓, RS = 1, R/W~ = 0 data = 0x20, CSB = 0, E = ↓, RS = 0, R/W~ = 0 data = 0x0C, CSB = 0, E = ↓, RS = 0, R/W~ = 0 Question 3. 3. (TCO 1) For the LCD configured in 8-bit mode, describe the signal conditions for CSB, E, RS, R/W~, and the data bits (D7 thru D0) needed to write the letter character ‘A’ from the microcontroller into the LCD module. (Points : 5) data = 0x41, CSB = 0, E = ↓, RS = 0, R/W~ = 0 4. (TCO 1) Describe how the 74C922 IC operates and its interface between the keypad and the microcontroller. (Points : 5) General Description The MM74C922 and MM74C923 CMOS key encoders provide all the necessary logic to fully encode an array of SPST switches. The keyboard scan can be implemented by either an external clock or external capacitor. These encoders also have on-chip pull-up devices which permit switches with up to 50 kΩ on resistance to be used. No diodes in the switch array are needed to
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