Analog.com Analog Dialogue Wiki 简体中文
EngineerZone
EngineerZone
  • Log In
  • Site
  • Search
  • User
  • Support

    Popular Forums

    • RF and Microwave
    • Power Management
    • Video
    • FPGA Reference Designs
    • Precision ADCs
    • Linux Software Drivers
    • SigmaDSP Processors & SigmaStudio Dev. Tool

    Product Forums

    • A2B
    • Amplifiers
    • Analog Microcontrollers
    • Clock and Timing
    • Data Converters
    • Direct Digital Synthesis (DDS)
    • Energy Monitoring and Metering
    • Interface and Isolation
    • MEMS Inertial Sensors
    • Processors and DSP
    • Switches/Multiplexers
    • Temperature Sensors
    • Voltage References
    View All

    Application Forums

    • Audio
    • Automated Test Equipment (ATE)
    • Condition-Based Monitoring
    • Depth, Perception & Ranging Technologies
    • Embedded Vision Sensing
    • Optical Sensing
    • Precision Technology Signal Chains
    • Video
    • Wireless Sensor Networks Reference Library

    Design Center Forums

    • ACE Evaluation Software
    • ADEF System Platforms
    • Design Tools and Calculators
    • FPGA Reference Designs
    • Linux Software Drivers
    • Microcontroller no-OS Drivers
    • Reference Designs
    • Signal Chain Power (SCP)
    • Software Interface Tools
    • System Demonstration Platform (SDP) Support
  • Learn

    Recent Discussions

    • Pluto + GNURADIO frequency change
    • Pluto SDR
    • pluto sdr pyadi-iio continous iq recording
    • attribute error
    • gps-sdr-sim is not working with my ADALM-PLUTO

    Places

    • ADI Education Home
    • ADI Education China
    • ADI Education India
    • ADI Education Philippines
    • StudentZone (Analog Dialogue)
    • Virtual Classroom

    Latest Webinars

    • Optimizing GaN and GaAs RF Amplifier Performance Using Novel Biasing Techniques
    • Webinar Improving Switch-Mode Power Supplies Using Noise Cancelling Technology
    • Webinar Accelerate Your Design With a 2 to 24 GHz Wideband Transceiver Reference Design
    • How to Design an Optimized Motion Control System for Intelligent Edge Based Surveillance Camera
    • How to Enhance High Precision Current Sensing Systems
    View All
  • Community Hub

    Challenge Yourself!

      KCC's Quizzes: Buffers and Fan Out
    View All

    Places

    • Community Help
    • Logic Lounge

    Resources

    • EZ Code of Conduct
    • Getting Started Guide
    • ADI: Words Matter
    • Community Help Videos
    View All
  • Blogs

     

    How To Design Fieldbus Agnostic Smart Factory Sensors

     

    You Passed EMC Testing… But Wait, Is There More?

    Latest Blogs

    • The 5 Things You Need to Know about RF Matching Networks
    • Does Reliability Prediction Uncertainty Justify Mandating Two Channel Safety?
    • An Inside Look at 2022
    • Meet the Person Behind the Quizzes
    • Updates Required: Why Newer is Better
    Read All Blogs

    ADI Blogs

    • EZ Spotlight
    • The Engineering Mind
  • Partners

    Electronic Design Services - PartnerZone

    • Boston Engineering
    • Calian, Advanced Technologies
    • Colorado Engineering Inc. (DBA CAES AT&E)
    • Clockworks Signal Processing
    • Epiq Solutions
    • Fidus
    • PalmSens
    • Richardson RFPD
    • Tri-Star Design, Inc.
    • VadaTech
    • Vanteon
    • X-Microwave
    View All
8052 Core Products
  • Analog Microcontrollers
8052 Core Products
Documents ADuC812: Status of the port on power-up
  • Q&A
  • Docs/FAQs
  • Members
  • Tags
  • More
  • Cancel
  • Documents
  • -ADuC812: FAQ
    • How to remove DAC zero Code error
    • ADUC812: Battery lifetime
    • ADuC812: Dealing with the interface I2C
    • Value of sample rate more higher that 200Ks are dangerous then customer never must use this value ?
    • ADuC812: enter serial download mode
    • ADuC812: Failure in restarting
    • ADUC812: Failure to Reset/Download
    • ADuC812: Flash reliability
    • ADuC812: glitches on the reset line
    • ADuC812: How to program external code space
    • ADuC812: latch-up
    • ADuC812: Measure ambient temperature
    • ADuC812: On Chip temperature sensor
    • ADuC812: Power down mode and choice of C compilers
    • ADuC812: Problems downloading to FLASH
    • ADuC812: PSEN pin
    • ADuC812: Reseting failure when downloading user program with WSD
    • ADuC812: serial interface
    • ADuC812: Status of the port on power-up
    • How do I migrate from ADuC812 to ADuC831 or ADu832?
  • +ADUC814: FAQ
  • +ADUC816: FAQ
  • +ADUC824: FAQ
  • +ADuC831: FAQ
  • +ADUC832: FAQ
  • +ADUC834: FAQ
  • +ADuC836: FAQ
  • +ADuC83x: FAQ
  • +ADUC841: FAQ
  • +ADuC842: FAQ
  • +ADUC845: FAQ
  • +ADuC847: FAQ
  • +ADUC848: FAQ
  • +ADuC84x: FAQ
  • +ADUC8xx: FAQ
  • +ADUCXX: FAQ

ADuC812: Status of the port on power-up

Q 

- I use AD812 and wonder must I set the port 2 and 3 to  input/output n SFR or
does it do that automaticly?

 

A 

Some information of the status of ports 0, 1, 2 and 3 on power up. Where the
ADuC812 deviates from the "standard" 8051, I will explain the standard
situation and the ADuC812 situation.

Port 0
In the standard 8051 microcontroller, port 0 is either a bidirectional I/O port
or a multiplexed data/address port for accessing external memory. This is also
the case for the ADuC812. As shown on the datasheet (p 18), the P0 SFR (addr
80h) powers up as all "1"s (FFh), i.e. configured as a digital input. In the
standard 8051 implementation, when port 1 is configured as an input it is an
open drain circuit with the pull-down FET turned off and with no pull-up FET.
This is also the case for the ADuC812 and so port 1 will power up as a high
impedance input with no internal pull up.

Port 1
Port 1 on the ADuC812 differs from the standard 8051 implementation.
In the standard AD8051 implementation, port 1 can be configured as either a
digital input of a digital output (writing a 1 to the port pin latch configures
the pin as an input, writing a 0 to the port pin latch configures the part as
an output).
In the ADuC812, writing a 1 to the SFR configures port1 as an analog
input.Writing a 0 to the SFR configures the port as a digital input. The
default power up condition for the Port 1 register is all "1"s (note the
datasheet on page 18 is contradictory as it gives the default Port 1 SFR
contents as all "0"s (incorrectly) but the hex value is correctly given as FFh.)
Therefore the ADuC812 port 1 powers up with port 1 as 8 analog inputs. The
input mulitplexer connects P1.0 (pin 1) to the input of the ADC, which will
look approximately like a 10k resistance to ground. The remaining pins of port
1 are high impedance inputs.

Port 2 and Port 3
Ports 2 and 3 on the ADuC812 are similar to the standard 8051 implementation.
They can be configured as inputs or outputs but also have secondary functions
associated with them. On power up, ports 2 and 3 are configured as inputs by
default and have an internal pull up resistor, which is capable of sourcing up
to 80uA of current e.g. if the input is connected to ground.

  • aduc8xx
  • aduc812
  • aduc8x
  • Share
  • History
  • More
  • Cancel
Related
Recommended
 
Social
Quick Links
  • About ADI
  • Partners
  • Analog Dialogue
  • Careers
  • Contact us
  • Investor Relations
  • News Room
  • Quality & Reliability
  • Sales & Distribution
  • Analog Garage
Languages
  • English
  • 简体中文
  • 日本語
  • Руccкий
Newsletters

Interested in the latest news and articles about ADI products, design tools, training and events? Choose from one of our 12 newsletters that match your product area of interest, delivered monthly or quarterly to your inbox.

Sign Up
Switch to mobile view
Analog Logo
© 1995 - 2023 Analog Devices, Inc. All Rights Reserved 沪ICP备09046653号-1
  • ©
  • 1995 - 2023 Analog Devices, Inc. All Rights Reserved
  • 沪ICP备09046653号-1
  • Sitemap
  • Privacy & Security
  • Privacy Settings
  • Terms of use
EngineerZone Uses cookies to ensure you get the best experience in our community. For more information on cookies, please read our Privacy & Security Statement.