PIC Microcontoller Memory Methods

• File registers
• File Select Register / Bank Select
• CompactFlash
  • http://www.barrymichels.com/ide IDE mode PIC interface. It works for hard drives and CF cards.
  • http://www.chipcenter.com/circuitcellar/february01/c0201ms1.htm interface a compact flash card to a Pic
• EEPROMs@ See: EEPROM Memory Corruption
  • Internal EEPROM access on 12CExxx devices
  • Internal EEPROM access on the 16F874/16F877
  • 24LC65 read/write from Tsvetan Usunov [usunov at OLIMEX.COM]
  • Ultra-optimised I2C EEPROM routines by Mike Harrison
  • USART, I2C, EERAM read/write, port setup, ISR, and full initialization sample from Tony Kübek of Flintab AB [tony.kubek at flintab.com]
• SIMM interface
• DRAM interface
• Software Stacks
• Table lookups
• Big Table Lookups (example for sound playback)
• Moving blocks of data in memory
• A system for text compression, expansion on the PIC or other embedded processor
• Testing memory, error detection, etc..
• Conditionally replaceing one value with another
• Tables on the 18C

Also:

• HeapManagementForSmallMicrocontrollersv1.03.zip Heap Management For Small Microcontrollers v1.03 by Isaac Marino Bavaresco These are a set of routines for PIC12/16/18, supports Hi-Tech PICC and PICC-18 and Microchip MPLAB-C18
• /Techref/member/roger_froud-virgin-/index.htm Here's a handy little program for a 18F2480 that allows you to embed a string in your program which is accessed by the preceding call. In this case, it's used to write strings to an LCD display but the principle is useful elsewhere.

See also:

• http://hackaday.com/2014/12/04/flash-memory-endurance-testing/ FLASH memory tests show endurance is much better than expected... at least on the PIC32MX150.
• http://www.bubblesoftonline.com/demo/dtimg.html Tony Nixons DT program has been updated and can now pack 2 7 bit ASCII chars into 14 bit words and generate the HEX code for it.
• http://lillith.sk.tsukuba.ac.jp/~kashima/games/gbread2e.html Parallel FLASH access.
• http://www.tech-tools.com/src10.htm Working code for interfacing to Atmel AT49F040 FLASH memory

Archive:

• PICList post "Save data to EEPROM on power failure or not..."
• PICList post "sorting 16bit values" Optimized swap macro and sort
• PICList post "False Alarm -- Accessing EEPROM"

Questions:

• ooibenglee@yahoo.com asks:

  Hi, I am trying to make an interface between a 16F877 and the EEPROM 24LC65. Does anyone has assembly routines for this interface? Moreover, does anyone can show me how am I going to connect 16F877 in order to write and read from EEPROM 24LC65???
  

• Can anyone help me with the proper code to read/write from eeprom of PIC12CE519. The Microchip code does not work and there is no help available anywhere for this specific device.
• David Köpfer asks:

  Hi
  I'm trying to step behind the programming of Pics but I'm having difficulties to get information. The Intel-Hex files are always organized in bytes, right? But now the programming memory of a 16f628 is 14 bit wide... How does that work now? do they use two bytes and just don't use the 2 spare bits of the most seginificant byte or do they write everything in sequence and I have to put them together and afterwards taking packages of 14?
  
  I hope anyone can help me...
  
  thank you David

• dsands@ev1.net asks:

  I'm looking for a string comparison code for a PIC16C84 to analyze file register data against multiple DB look up tables. Kind of like a user/password login, but I'm only using one external string (ie. the user name).

  James Newton replies: See: Code generator for keyword matching

• metjcp@hotmail.com asks: " I need a code witch uses look up tables , but the table has no logic for example '11011001100' represents 00 and '11001101100' represents 01" James Newton replies: Are you translating '11011001100' into 00 or the other way round? For matching a multiple byte 'string' see Keyword Interpreter Code Generator because your input is really a set of key 'words' that you want to recognize. To produce strings from a index byte, use a second index that is incremented for each character in the result string. Multiply the string index byte times the maximum number of character in an output string and add it to the character index. Now use a standard lookup table where each string is stored as a series of character entries in the table.

• For information on interfacing external memory to a PIC using the SPI interface, see /techref/microchip/spi.htm

Jim Miller Says:

Faced with creating two 128 byte tables today to replace a divide routine I created a spread sheet in Excel which created the decimal values, converted them to hex equivalents, split into high and low bytes and then concatenated them with "retlw" strings to create the table. I then pasted the two columns of retlw 'k' into PICASM.

Major labor savings!

Jim