ROM and RAM Emulator for 8051

Hardware emulator for the 8051 family with 64K RAM and 64K ROM

Table of contents:

• Features
• System Requirements
• Usage
• Principle of Operation
• Parts
• Download of Program and Circuit

Features

• No resources of the target MCU are used for emulation except of P0 and P2 for external memory.
• RAM and ROM of target MCU can be written.
• Readback of RAM content
• Fast programming: 5.7K bytes per second (AT89CXX typical 660 bytes per second)
• No programming cycle limit
• ROM and RAM contents remains valid during power off.
• Low part count
• Possibility to loop program for repeated programming
• Program supports batch mode.
• Communication protocol documentation
• Program is freeware for non-commercial use.

System Requirements

Usage

Parameter definition:

/h	help
/info	show full data transfer information
/slow	force slow mode, use if timing-code fails
/standby	loop program
/com:	select comport
/irq:	select irq for comport
/w:	write to program memory, uses hex-file, extension will be ignored and set to .hex
/read	forces /w: command to read data memory
/data	forces /w: command to work on data memory

If you use WinXX, you might create a link to emu on your desktop. Then you can insert there the command line. So you need only one click to send your program and one to close the window.

Otherwise you could also use the /standby option. Then you activate the window where emu is running and press simply a key. This especially useful during the development of a new program.

Emu does not cache the hex-file. It is read during the data transfer, therefor you can be sure that the latest version of the file is used.

If the green LED is on, the slave MCU is enabled. The MAX690 keeps the memory contents during power off. No resouces of the slave MCU are used. Wenn a SAB-C515 is used, it is possible to develop programs for the AT89-family easily by changing simply the port addresses. Remember that the address of the interrupt priority register at the 8051 is at the SAB-C515 the second interrupt enable register! Be careful also when you use the T2 of SAB-C515, compared to 8052 it is extended to a compare and capture unit. Do not ever write any 1's to bits that are not used by the basic 8051 architecture.

target MCU 87CXX	P0 open drain	P1	P2	P3
emulating MCU SAB-C515	P4 quasi-bidirectional	P1	P5	P3

Principle of Operation

Parts

• Semiconductors:
• 1 AT89C51 or AT89S51; see also programming tips
• 1 another 8051-Device maybe SAB-C515 or 80C552 check RST polarity
• 1 MAX232 or ADM232
• 1 MAX690 or ADM690
• 2 1N 4151
• 1 green LED
• 1 maybe: 1N4001 + 7805 + additional capacitors

  for other 8051 running at 12MHz:

• 1 74HC 00
• 1 74HC 157
• 1 74HC 573
• 1 8*128k static RAM max. 110ns

  for other 8051 running at 16MHz:

• 1 74AC 00
• 1 74AC 157
• 1 74AC 573
• 1 8*128k static RAM max. 70ns

  Capacitor:

• 4 33pF cer
• 8 100nF cer
• 5 10µF

  Resistors:

• 1 100
• 1 270
• 1 100k
• 1 10k *8 / 9 pin array

  Mechanic:

• 1 11,0592MHz crystal
• 1 crystal for the other 8051 device
• 1 Sub-D socket, 9 pin
• 1 cable, Sub-D plug-plug, 9 pin
• 1 pbc
• 1 some thin wire
• 1 low voltage power connector
• 1 socket 8 pin
• 1 sockets 14 pin
• 2 socket 16 pin
• 1 socket 20 pin
• 1 socket 32 pin
• 1 socket 40 pin
• 1 socket for the other 8051 device

Download of Program and Circuit

• emu.zip DOS program V2.00 with source code (for Power Basic 3.20), batch mode example, hex-file for MCU V1 with source code
• emu.gif circuit V1.00
• emucom.html communication protocol documentation

The part description in schematics is read as follows:
part type + value in exponential form + package description + subpart number in package
for example: C1040805,1 means Capacitor, 100nF, package SMD 0805, first subpart in package

Disclaimer: No warranty at all!
Copyright by Martin Clausen, Germany.
Contact the author: mc AT rotgradpsi DOT de
Impressum