Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.
-
Upload
eustacia-wells -
Category
Documents
-
view
225 -
download
4
Transcript of Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.
![Page 1: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/1.jpg)
Microprocessor
Dr. Rabie A. RamadanAl-Azhar University
Lecture 6
![Page 2: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/2.jpg)
Interfacing I/O Devices
2
![Page 3: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/3.jpg)
I/O modes Serial Mode
Data entered or exited in serial
Parallel Mode • Data entered or exited in parallel
• Interfaced through:• Peripheral mapped I/O
• Each device has a 8-bit address and enabled by I/O related control signals
• Memory mapped I/O
• Each device has a 16-bit address and enabled by memory related control signals
3
![Page 4: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/4.jpg)
Interfacing I/O Devices
The Z80 uses the instructions: •
• IN to read (input) data from an input device and
• OUT to write (send) data to an output device.
4
![Page 5: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/5.jpg)
OUT Instruction
It can send data from the accumulator, internal-purpose registers, or memory registers to an output device.
The OUT instructions include:
• 8 bit address of a device as an operand.
• The address range from 00H to FFH is called the I/O or peripheral map,
• An address can be referred to as a device address, port address, or port number.
5
![Page 6: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/6.jpg)
Example
When the microprocessor reads and executes the machine codes written at memory register 2050H and 2051H, it will transfer (copy) the byte from the accumulator to the LED port with address 07H and display the byte.
6
![Page 7: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/7.jpg)
Execution of OUT Instruction and Timing
The OUT has three machine cycles;• Opcode Fetch,
• Memory Read and
• I/O Write.
The Z80 reads the opcode and the port address
from memory in the first two machine cycles and writes into the port in the third cycle.
7
![Page 8: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/8.jpg)
Execution of OUT Instruction and Timing
8
![Page 9: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/9.jpg)
Execution of OUT Instruction and Timing
9
![Page 10: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/10.jpg)
Basic Concepts in Interfacing Output Devices
10
![Page 11: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/11.jpg)
Basic Concepts in Interfacing Output Devices
11
![Page 12: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/12.jpg)
Illustrative Example 1: Interfacing LEDs
Hardware 7475 Latch
• 4 D-Latches
• 2 enable lines
47LS373 Octal Latch
• Latch followed by
tri- state buffer
• Reduces using
the data bus
• 8 latches instead of 4
12
![Page 13: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/13.jpg)
Interface Circuit
13
![Page 14: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/14.jpg)
Interface Circuit
14
![Page 15: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/15.jpg)
Using a Seven-Segment LED as a Display Device
15
![Page 16: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/16.jpg)
Using a Seven-Segment LED as a Display Device
16
![Page 17: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/17.jpg)
Interfacing INPUT Devices
IN instruction
• Read (copy) data from such input devices as switches, keyboard, and A/D data converters.
• Can read an input device and place the data into the accumulator, Z80 registers, or memory registers.
17
![Page 18: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/18.jpg)
Example
First read the machine codes stored at locations 2065H and 2066H,
Read the switch positions at port 84H by enabling the interfacing device of the port.
The data byte indicating switch positions from the input port will be placed in the accumulator.
18
![Page 19: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/19.jpg)
Execution of IN Instruction and Its Timing
The IN instruction has three machine cycles:
• Opcode Fetch,
• Memory Read port address
• I/O Read.
19
![Page 20: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/20.jpg)
Execution of IN Instruction and Its Timing
20
![Page 21: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/21.jpg)
Illustrative Example : Interfacing Input Switches
21
![Page 22: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/22.jpg)
Multiple Port Addresses
the address lines A4 and A3 are not used by the decoding circuit; the logic levels on these lines can be either 0 or 1.
22
![Page 23: Microprocessor Dr. Rabie A. Ramadan Al-Azhar University Lecture 6.](https://reader035.fdocuments.us/reader035/viewer/2022062300/56649e685503460f94b63bbd/html5/thumbnails/23.jpg)
Some other examples from the book
23