hi i am doing a project where i have to read a 2 byte hex code from a Card reader , in an external ROM create a table with every code corresponding to a num , once the code is read extract the corresponding num and display it . i am using 8255 and using 2 of its ports to read the code and one port to connect to a display unit having 5 seven segment displays . is this the most efficient way for this application . i am a amature in this field and am finding the programming part a bit difficult
external ROM for data storage ROM = Read ONLY memory. How do you propose to store data in a read ONLY device? Erik
It sounds to me that for this application, the ROM is a fixed lookup table. It could be anything from a pre-programmed flash or EEPROM to OTP to a mask ROM. The method of programming would really depend on their manufacturing environment and volumes. The bar code readers I'm familiar with use a serial interface rather than a parallel one, and would be connected to an 8051 UART (SPI, I2C, etc). You haven't mentioned exactly what the device is, so perhaps a parallel interface is appropriate. Similarly for your numerical display; without part numbers, we can't really know what the interface is. Selecting an appropriate 8051 variant would give you the I/O ports built into the microcontroller. The external ROM will kill P0/P2 on many variants, which still leaves P1/P3. If the interface to the reader or display could be serial, then you can eliminate the 8255 from the board. (The point of a microcontroller is to eliminate the glue logic and components, after all.)
hi actually i plan to use a NVRAM my application is to create a attendance sheet for a company . They are using punch card readers with a 2 byte code.. i plan to use there existing card reader and display. read it using 8051 and store the attendance timing in the RAM , and transfer the days attendance over RS-485 to a PC i am making this application for my undergraduate project for B-Tech degree . o know C pretty Well but having difficulties in understandin embedded C for KEIL uvision due to lack of any books or guidance. can u suggest me any books for the same
o know C pretty Well but having difficulties in understandin embedded C for KEIL uvision due to lack of any books or guidance. can u suggest me any books for the same "can u suggest": I do not know what micro can suggest, but Andy, I'm sure, will guide you to the uVision Getting Started Guide. As for me I will state that any attempt to program the '51 will be a failure, if you are not familiar with "the bible" Erik here are the links to "the bible" Chapter 1 http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_ARCH_1.pdf chapter 2 http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_PROG_GUIDE_1.pdf chapter 3 http://www.semiconductors.philips.com/acrobat/various/80C51_FAM_HARDWARE_1.pdf
hi i have a working knowledge of 8051 and progrmming in assembly language .. i waz looking for refrences in embedded C
i waz looking for refrences in embedded C Which you got here: can u suggest me any books for the same "can u suggest": I do not know what micro can suggest, but Andy, I'm sure, will guide you to the uVision Getting Started Guide. Erik