Remote-processing RPC-220 Manual de usuario descargar pdf (Pagina 14)

WRITING, DEBUGGING, AND SAVING PROGRAMS SECTION 3

Page 3-3

Monitor source code and hex file are under the MON220

directory.

Some internal registers and ports are initialized upon

power up and program break. These include registers

associated with COM0, RAM segment, and timers.

A partial list of modified registers include: S0CON,

TMOD, TCO N, TL1, TH1 and all of the registers in

bank 0. Review the source code, under the programs

"MAIN220. ASM" and "STA RT220. ASM" to determine

which registers are used and how they might affect your

code.

External RAM from address 0x7fc0 to 0x7fff are used

by the monitor to store break points and registers. M ake

sure your program does not write in this area if you

intend to use these.

Effects of the Monitor on a Program

The monitor program minimally modifies RAM and I/O

ports during its normal operation. There are some

modifications the mon itor does to operate. These effects

are most noticeable during brea ks.

RAM segment is reset to 0 upon entry. The RAM

examine command (DX) temporarily modifies the

segment during access only.

I/O mode is reset to RAM.

Interrupts are turned off via the IEN. 7 bit in the

interrupt register.

The monitor sets its stack to address 0x60.

' register ' or internal RAM variables at or above this

address may get c orru pted or otherwise not reliable

using the DI command.

After a reset, the 8051 stack is automatica lly set to

internal address 7. ' register' or internal RAM from

0x08 to 0x0c get modified. The only time this is a

problem is when you reset the card and want to look

at data in this area. To solve this problem in C,

simply declare 4 'dummy' integer registers before

the others.

Ports and registers are restored for Goto comm ands

except P4.1. This bit controls the development mode and

is always set low on GOTO.

MONITOR COMMANDS

The following describe command function and operation

in greater detail. The monitor displays a summary when

' H' or ' ?' is entered.

All numeric data is entered a s HEX . An address is up to

4 bytes long. Any address less than this assumes leading

0' s.

Pressing the < esc> key at any time aborts a command.

Commands with parameters in [brackets] are optional. If

nothing entered, 0 is assumed for that and any remaining

parameters. For example, if an address and segment are

parameters of a command but nothing is entered for

either, then 0 is assumed for both.

Commands with multiple parameters are separated by a

comma (, ).

An Enter (< cr> ) executes a comm and in most cases.

Some commands, such as DI and H, execute as soon as

the key is hit.

Display Commands

There are 5 display com mands:

DX Display eXternal memory

DI Display Internal memory

DP Display Port or I/O d ata

DR Display Registers

DS Display Special function registers (80H -

FFH)

Data is displayed 16 lines at a time (except for registers).

The segment, if applicable, followed by the address

starts off a line. Up to 16 bytes of data are displayed,

followed by printable A SCII character s. P rintable

characters are those from 20H - FFH.

DX Display external memory

External memory is RAM on the RPC-220 card. It

is accessed using a segment:memory type scheme.

Comm and format is:

DX [address[,segment]] <ret>

If DX is simply entered, the monitor assum es address

and segment 0. If an addr ess is entere d but no segm ent,

then segment 0 is assumed.

DI Display internal memory

Internal m emory is RAM internal to the CPU . It is

fixed at 256 bytes. Comm and form at is:

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 46 47

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