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Bachelor's Degree in Telecommunications Systems and in Network Engineering |
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L9.2: Basic I/O. Planning projects: general organisation of hardware and software. [P9] Hardware circuit, init_system() |
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3.4.2. Planning
3.4.2.1. Hardware schematic
3.4.2.1.1. Connecting switches and buttons
3.4.2.1.2. Oscillator (OSC) and reset (MCLR_L) circuits
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Fig. 1. Example of typical external quartz crystal Oscillator. |
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Fig. 2. Example of typical external MCLR_L circuit (CD_L): Power-ON reset (RC) network and active-low push-button for initialising the microcontroller.
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3.4.2.1.3. Interfacing LED
3.4.2.1.4. Tri-state logic gates and wire bi-directionality. Bus concept.
The idea of tri-state gates and bidirectional wires and buses.
3.4.2.2. Software program
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| Fig. 3. Software organisation flowchart. |
3.4.2.2.1. RAM variables
3.4.2.2.2. init_system(): I/O port pin configuration register (TRIS).
Our goal: How to configure a port pin as input or as output. TRIS data direction register.
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Fig. 4. Example of pin direction configuration. |
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Let discuss all there ideas designing an example circuit.
3.4.4.2. Adder_BCD_1digit
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