Remote-processing RPC-220 Manual de usuario descargar pdf (Pagina 18)

WRITING, DEBUGGING, AND SAVING PROGRAMS SECTION 3

Page 3-7

SAVING YOUR PROGRAM TO FLASH

Your program is saved to flash EPROM when

development is done or when you wish to make sure a

program works proper ly.

Usually, but not always, the monitor is replaced. T his

means the save to flash feature will be gone UNLESS

you put it in your program. See "WRITING CODE

FOR U PDA TES" below for taking care of this situation.

You can put code or data in a portion of the flash using

the monitor save command. Howe ver, if you over write

starting at address 0 to a bout 1900H , the monitor is

effectively destroyed.

The ' S' command transfer s the actual prom burning

routine RAM starting at address 0xff00 and executes

from there. M ake sure none of your program is located

in this area.

While pr ogram ming is in pr ogress, the letter ' P' is

printed for every 512 bytes program med (about 100

milli-seconds). The letter ' V' is printed on the next line

for every 512 bytes verified. If there is a verify error, a

letter 'E' is printed at the 512 byte block it was verifying

and the programming process stops.

After verifying good, code jumps to address 0. You

may want to press reset to simulate pow er on conditions.

Saving Process

You can use the monitor code (mon220.hex) to get a feel

for saving code. Save this code to an EP ROM address

not used (such as 0x4000). Then use the DP com mand

to view the contents of the EPROM.

The saving process consists of 2 steps:

First, down load code to RAM using the ' R' command.

Do not specify an offset. Begin saving at address 0.

Second, save to flash by e xecuting the ' S' command. Its

syntax is:

S RAM address, EPROM address, length

All parameters are in hex format. RAM and EPROM

address are usua lly 0. T he only real figuring to do is

length. A quick w ay to check is fir st ' F' ill RAM with

all 0' s from 0 to 0x7fff. Down load the code. T hen use

the ' DX' comm and to view your code. W hen data is all

0' s, you can take the highest address and use it as your

length.

NOTE: The flash E PRO M is pr ogram med in 64 byte

blocks. The saving routine stops when the

length is reached. FF' s are pr ogram med in

locations not specified to round out the block.

NOTE: Since the flash EPROM is programm ed in 64

byte blocks, you should star t on an even byte

boundary. An ' even' boundary is 0xXX00,

0xXX40, 0xXX80, or 0xXXc0.

WRITING CODE FOR UPDATES

There are tw o ways to field update code . O ne method is

listed in the /LOADE R directory. There, a loader

program always resides in memory. You just set a line

low and the loader program is invoked. Programs are

stored starting at address 400H. Review the readme files

for more inform ation.

The second way is to embed a save routine in your code.

This is discussed further below.

A sample routine in FLASH \PFLASH.C is complete

code to prompt the field person to download and burn a

new program . It r eceives Intel H ex code, puts it to

RAM, uploads the flash burn program into RAM, and

runs it. How you get to this routine is up to you. You

could check a line status or check a password through

the serial port or any number of different means.

In-circuit Reprogramming

The general strategy is to temporar ily go into

development mode. The ROM code puts programming

code in RAM, sets the development mode bit, and jumps

to it. Sample code is under the "flash" directory.

Most likely new code is transferred through the serial

port. You should allow for some character code or

sequence to put the card into programming mode. Using

the "FLASH. C" program as an example, the code

receives lines of hex, buffers them, and programs the

flash 64 bytes at a time. After program ming, the code

resets the development bit and jumps to CPU address 0.

You cannot read or execute from flash while it is writing

new data into itself. Ther efore, you must suspend all

other processes. M ake sure you turn off interrupts.

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