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Understanding Output Observations
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To start, let’s discuss how we verify the output through the LED displays connected to Port A. What do you think will happen when we send data to Port A?
I think the LEDs will light up in a pattern based on the data we send, right?
So if we send '55H', they should not all be on but alternate between on and off?
Exactly! Each '1' in the binary representation turns the corresponding LED ON, while each '0' turns it OFF. This way, you can visualize the output data directly.
What do we do if the LEDs don’t light up as expected?
Great question! We need to troubleshoot by checking connections, ensuring the correct data is sent, and confirming the assembly code doesn’t contain mistakes.
To summarize, observing LED states helps us confirm the correct data handling of our output port. If you sent '55H' to Port A, you should see the LEDs as ON, OFF, ON, OFF, ON, OFF, ON, OFF.
Handling Input Switch Observations
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Now, let's talk about reading switches' states from Port B. When a switch is activated, how does that affect the data we receive?
If a switch is pressed, it changes the state related to that bit in the input data, right?
Correct! The pressed switch corresponds to a '1' in the input data for that bit. By sending this data to Port C, we can visualize the state of the switches through LEDs.
And we need to continually check the state of the switches, so we should loop our reading command?
Precisely! This looping ensures we stay updated with any changes in switch states. After reading, we will constantly send that data to Port C.
In summary, activating switches sends a specific byte to the microprocessor. Observing this in action is crucial for confirming our code works as intended.
Examining Registers After Input/Output Operations
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Let’s examine the process of verifying register contents after executing input or output commands. Why is this step important?
We need to ensure that the data we thought was sent or received actually made it to the correct registers!
Exactly! By checking registers like the Accumulator after an 'IN' command, we can see the actual data received from Port B.
So we’ll use instructions like EXAM REG after each read to confirm the behavior?
That’s right! Use commands to display the register contents after executing your programs. This will confirm all operations were successful.
In conclusion, examining register values is essential to validate correct data flow between the ports and the 8085 microprocessor.
Introduction & Overview
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Quick Overview
Standard
The observation section covers the practical exercises performed on the 8085 microprocessor interconnected with the 8255 PPI. It emphasizes verifying output through LEDs, and reading inputs via switches, alongside suggestions for documenting findings and program performance.
Detailed
Detailed Summary
In this section, we delve into the Observation phase of interfacing the 8255 Programmable Peripheral Interface (PPI) with the 8085 microprocessor. The primary emphasis is on verifying the configurations applied through initial assembly programming and observing the resultant behaviors through connected output and input devices. The steps outlined include:
- Observing Output LEDs: Students will visualize LED states based on output data sent to Port A, verifying correct functionality.
- Observing Input Switches: By changing switch states and reading values from input ports, students can confirm accurate data fetching by the microprocessor.
- Examining Registers/Memory: After input operations, examining the state of registers and memory allows students to validate that the data was processed correctly. The importance of methodically recording observations for each executed program is stressed, ensuring students can analyze performance against expected outcomes.
Audio Book
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Observing Output LEDs
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- Observe Output LEDs: For programs configuring ports as output, visually observe the state of the connected LEDs (ON/OFF) as the program executes.
Detailed Explanation
When you execute programs that set certain ports as outputs, you can check the behavior of the connected LEDs. If a program sends a high signal (ON) to a port connected to an LED, the LED should light up. Conversely, if it sends a low signal (OFF), the LED should go dark. By running your program, you can actively see if everything is functioning as expected by checking which LEDs are lit at any given moment.
Examples & Analogies
Imagine turning a light switch on and off. Each time you execute a portion of your program, it's like flipping a switch; if it's on, the LED is lit (the room is illuminated), and if it's off, the LED is dark (the room is dark).
Observing Input Switches
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- Observe Input Switches: For programs configuring ports as input, change the state of the connected switches and then read the corresponding input port using the program. Verify the read data on the display or by checking register contents.
Detailed Explanation
With programs set to read from input ports, you can manipulate the switches connected to these ports (like pressing a button). The program will read the state of these switches (whether they are ON or OFF). This information can be displayed on the screen or stored in registers in the microprocessor. By changing the switch states and seeing the corresponding output, you can confirm that the reading from the input port is correct.
Examples & Analogies
Think of it as a game where you press different buttons and see different outcomes displayed on a scoreboard. Each press (change of the switch state) sends a message to the computer, and the way the scoreboard changes tells you if the message was received correctly.
Examining Registers/Memory
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- Examine Registers/Memory: Use the trainer kit's commands (EXAM REG, EXAM MEM) to verify the contents of the Accumulator and other registers, especially after IN instructions to confirm input data was correctly read.
Detailed Explanation
After reading inputs from an external source (like switches), it's important to check what data has been stored in the Accumulator or other registers. Use commands like EXAM REG or EXAM MEM on your 8085 trainer kit to see these values. If your reading executed correctly, the value in the Accumulator should reflect the state of the input ports, allowing you to confirm the program's accuracy.
Examples & Analogies
Imagine counting how many apples you have after picking them from a tree. After you pick the apples (read data), you check your basket (the Accumulator) to see if you counted correctly. If you see five apples (the expected value in the register), you know your counting was accurate.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Observation Phase: The step where students verify the correct function of their interface after programming.
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Output Verification: Confirming LED states reflect the programmed output byte.
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Input Reading: Continuously checking the status of switches and sending data to output LEDs.
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Registers Examination: Ensuring data flow accuracy by reviewing the state of registers after operations.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
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If the output to Port A is set to 'AAH', the connected LEDs should display a pattern of alternating ON and OFF.
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Reading from switches on Port B while activating them should reflect changes in the LED states connected to Port C.
Memory Aids
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🎵 Rhymes Time
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When the switches press the bits go high, and the outputs blink to the eye!
📖 Fascinating Stories
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Imagine a classroom where each student pushes a button representing a light switch. As they press, the room lights change, reflecting their actions, learning how input influences output.
🧠 Other Memory Gems
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Remember: Read, Check, Observe, and Display (R-C-O-D) for effective observations.
🎯 Super Acronyms
LED stands for Light Emitting Diode; think 'LED - Lights Emit Data!'
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
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Term: LED
Definition:
Light Emitting Diode; a semiconductor device that emits light when current flows through it.
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Term: PPI
Definition:
Programmable Peripheral Interface; a device that allows a microprocessor to communicate with peripheral devices.
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Term: Accumulator
Definition:
A register in the microprocessor used to store intermediate results of arithmetic and logic operations.