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Frequently Asked Questions

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8052 Background Questions

  1. Where can I find documentation and FAQs for the 8051 family?
  2. What is an 8052 Microcontroller?
  3. Glossary of terms and abbreviations commonly used on this website?
  4. What are the most common pitfalls for a 8052 newbie?
  5. Can I run Linux on the 8052?
  6. I prefer Java. Can I program using Java for the 8052?
  7. I prefer C++. Can I program using C++ for the 8052?
  8. I'm a Windows 'C' programmer. Will it be hard for me to program the 8052?
  9. Can I use Microsoft Visual Basic/Microsoft Visual C++/Borland C++/etc. to develop 8052 applications?
  10. I'm a Windows Visual Basic programmer. Will it be hard for me to program the 8052?
  11. What is a derivative microcontroller / derivative chip?
  12. What hardware do I need to do 8052 development?
  13. What software do I need to do 8052 development?

Compiler/Tool Questions

  1. What is the difference between an interpreter, assembler, and compiler?
  2. Should I program the 8052 in assembler, 'C', or some other language?
  3. What 'C' cross-compilers exist for the 8052?
  4. Are there any free assemblers or 'C' compilers for the 8052?
  5. I prefer to program in Pascal. Can I do it on the 8052?
  6. What is the difference between a simulator and emulator?

Timers/Counting Questions

  1. How can I count something with high frequency?
  2. How can I use a timer to count 5 seconds?

Serial Communications Questions

  1. How to make a software UART?
  2. Why does my RS-485 not work ?
  3. Is there some basic RS232 guide for 8052 users?
  4. Can I mix Tx in "main" and Rx in interrupt?
  5. How do I set the serial port baud rate?
  6. I used the formula to calculate a baud rate, but I get a fractional value for TH1. What should I do?
  7. When should I set and/or clear TI bit of SCON?
  8. My program is writing garbage to the serial port. Why?
  9. My program uses the serial port but doesn't seem to send any data. Why?
  10. I'm trying to receive data with the serial port but never receive anything. Why?
  11. I send one byte to the 8052 and I'm receiving that byte over and over indefinitely. Why?

Interrupt Questions

  1. What is meant by "high level" and "low level" interrupts?
  2. why should i not just reenable the interrupt?
  3. What are interrupts?
  4. How (not to) shoot yourself in the foot, using interrupts?
  5. Does an interrupt provide multitasking?
  6. When would I use level triggered interrupts, not edge ?
  7. Once in an interrupt, and then in a high-level interrupt, can both interrupts be cancelled?
  8. What can edge-triggered interrupts be used for?
  9. My program uses interrupts, but my interrupt only executes once. Why?

Input/Output Questions

  1. What is input (e.g. pushbutton) debouncing?
  2. I ran out of I/O pins on my microcontroller. How can I get more?
  3. What variations are there in accessing external memories (MOVC, MOVX)?
  4. Does output logic "low" represent 0V?
  5. How do Quasi-Bidirectional I/O ports work?
  6. How to drive a +12V load (e.g. a relay) from 8051 port pin?
  7. How to set the '51 port pin into input (output) mode?
  8. When I set port pin to 1, there is much lower voltage than 5V on it, why?
  9. How can I read a value from an I/O line of the 8052?
  10. What value do the I/O output latches default to?
  11. How can I bring an I/O line high?
  12. How can I bring an I/O line low?

Software Questions

  1. Is there a way to read the value of the Program Counter (PC)?
  2. How are lookup tables implemented in 8052 assembler?
  3. How do I convert HEX to ASCII code in assembler?
  4. what is all this atomicity stuff anyhow?
  5. Is there a floating point (FP) package available for the 8052?
  6. I get an assemble error when I try to PUSH/POP the accumulator. Why?
  7. What is a software State Machine all about?
  8. How shall I end my program?

Hardware Questions

  1. How can I resolve noise problems?
  2. what about analog to digital converter ?
  3. why should I use a 'strange' crystal frequency ?
  4. What are FPGAs and CPLDs and how are they used?
  5. how do I mix 3.3V and 5V ?
  6. Can 8052 be used with Smart Cards?
  7. Why do I need a Latch for external memory?
  8. How to program (burn) the code inside my 8051-derivative microcontroller?
  9. How can I reduce EMI in my design?
  10. How do I interface an 8255 to an 8052?
  11. What alternatives are there to using an 8255?
  12. How can I improve EMC in my design?
  13. What are some good PCB layout tips?
  14. What is a reset generator?

Other Misc. Questions

  1. My code does not work. Any help?
  2. Can TCP/IP be implemented with the 8052?
  3. Can I decode a barcode with an 8052?
  4. Can the 8052 dial a phone?
  5. Can I decode DTMF dial tones with the 8052?
  6. How can an 8052 determine temperature?
  7. Is there an IrDA stack for the 8052?
  8. What is the difference between a ucontroller, PLC and DSP ?
  9. Any good school (final year) project?

Message Forum Questions

  1. Why are message threads occasionally closed?
  2. Who are the moderators of the forum?
  3. Why are messages or entire threads occasionally deleted completely?
  4. Do I need to be a registered user to post?
  5. How can I make "My Home Page" visible in the User Pages list?
  6. Can you delete my account or posts?
  7. How to search on
  8. How can I post formatted code? Site Questions

  1. Who is the Webmaster of
  2. How long has been online?
  3. Can I advertise on
  4. How many "hits" does receive per month?
  5. Is for sale?
  6. Who wrote and developed