CAn you run PIC18 or PIC32 with external ROM?

[3BABY]

Hi Guys,

this is a question that has been bugging me for a while now, is it possible to run some of the larger pin count Micochip PIC's with external ROM and not use any of the internal ROM??

thanks,

 

[bigdogguru]

By ROM do you mean flash or EEPROM?

Several of the PIC18s have an External Memory Interface (EMI) feature:

EXTERNAL MEMORY INTERFACE (EMI) OVERVIEW

External Memory Interface offers the user many
options, including:

• Operating the microcontroller entirely from
external memory
• Using combinations of on-chip and external
memory up to the 2-Mbyte limit
• Using external FLASH or EEPROM memory for
reprogrammable application code or large data
tables
• Using external RAM devices for storing large
amounts of program or variable data
• Using external memory mapped devices and
peripherals

Reference: AN869 External Memory Interfacing Techniques for the PIC18F8XXX

The PIC24, dsPIC33 and PIC32 have a Parallel Master Port (PMP) interface which you can access external data memory, FLASH or SRAM, however it lacks the feature of executing code in external storage.

Parallel Master Port

AN1210 Using External Data Memory with PIC24F/24H/dsPIC33F Devices


If you need additional storage for data such as images, webpages, etc, then there are several options available ranging from I2C/SPI EEPROM to SD Flash Cards.

There has been some discussion of producing a PIC32 with similar EMI features as the PIC18F8XXX in future releases.

BigDog

 

[3BABY]

By ROM do you mean flash or EEPROM?

...

There has been some discussion of producing a PIC32 with similar EMI features as the PIC18F8XXX in future releases.

BigDog

Thanks BigDog for the very complete answer.. yeah basically i just wanted some extended Program Memory.. so running the MCU in Microprocessor mode will work.. so the whole system would function more like a small RISC microcomputer..

it would be nice to see a PIC32 with the same EMI features!!

Many thanks!