Programmable Interface Device used to interface a I/O device to the microprocessor Intel has designed several PPI chips (e.g. 8155, 8156, 8255) to interface I/O devices. *Analog to digital conversion *Digital to Analog conversion

1. Presentation topic
 Programmable Peripheral Interface
 Analog to digital conversion
 Digital to analog conversion
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2. Programmable Interface Devices
 Programmable Interface Device used to interface a I/O device to the
microprocessor
 It is designed to use in minimum mode system
 It contain RAM, I/O ports and Timer
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3. 8155 – A multipurpose programmable interface
 Designed to be compatible with 8085
 It includes :
 256 bytes of Read/Write memory
 Three I/O ports : Port A (8-bit), Port B (8-bit) ,
Port C (6-bit)
 A 14-bit timer
 Internal address latch to Demux AD0-AD7.
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4. Block Diagram - 8155
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5. Need of PPI
 If the system is designed using buffer and latches (i.e. ports) to
interface input and output devices, it is not possible to change any
input device with the output device or vice-versa.
 Intel has designed several PPI chips (e.g. 8155, 8156, 8255) to
interface I/O devices.
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6. Analog to digital conversion
 Analog to digital conversion means changing analog signal to digital data.
 Various techniques used are:
1) Pulse Code Modulation(PCM) and
2) Delta Modulation.
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7. Application of ADC
 Used in microcontrollers.
 Used in digital signal processing.
 Used in digital storage oscilloscopes.
 Used in scientific instruments.
 Used in music reproduction technology etc.
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8. Digital to Analog conversion
 Digital to analog conversion is the process of changing one of the
characteristics of an analog signal based on the information in digital data.
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9. Digital to Analog conversion method
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10. Applications of DAC
 Digital Signal Processing
 Digital Power Supplies
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11. End of presentation
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