mobile | classic
Dataweek Electronics & Communications Technology Magazine

Follow us on:
Follow us on Facebook Share via Twitter Share via LinkedIn


Electronics Buyers' Guide

Electronics Manufacturing & Production Handbook 2019


A brief look at emulation technologies
25 September 2002, Design Automation

Microcontrollers have I/O lines for user applications. Sometimes these lines can be used either as I/O or bus, depending on the memory location. If the microcontroller is a ROMless device, instructions are fetched outside the device and as the bus is always there, an emulator can be built around it. The main issue is how to emulate a microcontroller in ROM mode, which means when the instructions are fetched inside the chip memory and the I/O lines remain unchanged until a related instruction that affects them is executed. ROM is now not necessarily a Read Only Memory, but it can also be a device with Flash technology, meaning a memory that holds the user code without being erased while power goes down.

Figure 1. Standard microcontroller
Figure 1. Standard microcontroller


Emulators need access to the internal bus especially when the bus signals are shared with I/O lines or when there is no external bus available at all. As a solution the silicon manufacturers used to produce bond-out chips which are the same microcontrollers mounted in a bigger package with more pins that provide the internal bus, status and control signals. I/O lines and the internal bus are accessible through different pins in the chip. Bond-outs are needed only for the emulator vendors.

Figure 2. Bond-out
Figure 2. Bond-out

Emulation mode

A solution came a few years ago that consisted of multiplexing the I/O lines with the internal bus while entering the chip into a special emulation mode - an undocumented feature licensed only to emulator vendors. A pattern is sent to the standard chip through one of the pins while the microcontroller is reset. With the addition of external logic, I/O lines are sampled and reconstructed, while the internal bus is available on a different time slot. The major advantage of the emulation mode is that all the emulation functions are already implemented in the standard silicon, so with new versions of the chip also the emulators are automatically updated. This mode is also called 'Emulation Hooks'. I/O lines are fully reconstructed and the user has available all I/O features as in the actual devices.

Figure 3. Emulation mode
Figure 3. Emulation mode

ROM and ROMless support

Some silicon vendors do not have any solution for emulators - this means their microcontrollers do not have Emulation Mode or available bond-outs. Therefore, there are a few solutions for emulation:

1. Use a similar chip from other vendor in the emulator. For the emulator it does not matter which is the memory technology (EPROM, Flash, etc) so for example a chip like 89C51 (Flash type) can be emulated by an 87C51 (EPROM type).

2. Use the chip in ROMless mode. In this case the emulator may have placed exactly the same silicon as the final design. Nevertheless, the chip will work in ROMless mode. This is not a problem in some cases. For example if the device is an 8051 derivative and the user code executes MOVX instructions to access data outside the microcontroller, activating Port 0 and 2 as buses, a ROMless type can be used because in any case port contents are changed.

Low pin count microcontrollers

Sometimes these devices can be emulated using a similar device with standard pinout and a socket converter. For example most of the 20-pin devices have a 40-pin superset with all the same functionality and more. This may not solve all the problems because the small devices may also have pins with dedicated functions not available in any other device.

Flash microcontrollers

The Flash technology is now being added to all new microcontrollers to implement the code memory. Flash technology includes ISP and IAP. The ISP (in-system programming) allows loading the user code without removing the chip from the target circuit. The IAP (in-application programming) may be used to let the code to modify itself without affecting I/O lines or activating a bus, and this is also a very basic need of emulators.

All the available emulators work in emulation mode or using bond-outs or in ROMless mode, thus allowing access to the internal buses. Therefore, the actual code is in the emulator overlay RAM memory and not in the microcontroller Flash. So, ISP or IAP is never used by the emulators. This is a problem for many users that want to emulate these features. Ceibo developed a new technology that is being implemented by several silicon vendors, which with the addition of a few internal registers inside the microcontroller, all the basic emulation functions are already inside the chip. These capabilities are trace memory, breakpoints, code downloading, register modifications and others. The FE-xxxx series of emulators is now available for microcontrollers produced by Atmel M&W, Dallas Semiconductors, Winbond and Philips. Some others will be added soon.

Supplied By: Sivan Electronic Supplies
Tel: +27 11 887 7879
Fax: +27 11 887 2051
  Share on Facebook Share via Twitter Share via LinkedIn    

Further reading:

  • Altium Designer gets 2019 update
    30 April 2019, EDA Technologies, Design Automation
    Altium Designer 19, the latest version of the company’s flagship PCB design software, introduces new features aimed at making the design of complex, high-quality projects easier, faster and more accurate, ...
  • DesignSpark surpasses 750 000 members
    30 April 2019, RS Components (SA), Design Automation
    RS Components’ DesignSpark online engineering community has grown to more than 750 000 members. Launched in 2010, DesignSpark provides design engineers and students around the globe with free tools, ...
  • Python programming comes to Nordic’s multiprotocol SoCs
    30 April 2019, RF Design, Design Automation
    Nordic Semiconductor announced that Zerynth, a New York-based Internet of Things (IoT) software developer, has extended the availability of its ‘Zerynth IoT middleware’ to Nordic’s nRF52840 Bluetooth ...
  • Würth extends design tool’s functionality
    30 April 2019, Würth Elektronik eiSos, Design Automation
    Würth Elektronik eiSos has extended its free online design tool, REDEXPERT. The simulation software is a highly precise option for AC loss calculation in switch mode power supplies, and now supports calculations ...
  • Espressif jumpstarts ESP32 development
    30 April 2019, Icorp Technologies, Design Automation
    Espressif Systems has introduced two tools to assist developers using its ESP32 microcontroller platform in simplifying and speeding up their designs. As developers know, building production-ready firmware ...
  • Motor drive evaluation board
    27 March 2019, Altron Arrow, Design Automation
    Infineon Technologies’ EVAL-M1-IM818-A evaluation board was developed to support customers during their first steps of applications with CIPOS Maxi IPMs (intelligent power modules). In combination with ...
  • Extruded aluminium enclosures
    27 March 2019, Sivan Electronic Supplies, Enclosures, Racks, Cabinets & Panel Products
    The extruded aluminium enclosures of Gainta’s ALUG7XX series are available in different sizes, with lengths suitable for indoor desktop device or outdoor wall-mounting junction/control box use. Five ...
  • Würth extends design tool’s functionality
    27 March 2019, Würth Elektronik eiSos, Design Automation
    Würth Elektronik eiSos has extended its free online design tool, REDEXPERT. The simulation software is a highly precise option for AC loss calculation in switch mode power supplies, and now supports calculations ...
  • 300 W PSU for medical electronics
    27 March 2019, Sivan Electronic Supplies, Power Electronics / Power Management
    Cosel’s GMA300 AC-DC power supply provides up to 300 W in a package measuring 5,08 x 10,16 cm and 1U high. Fully compliant with IEC60601-1 3rd and 4th editions, as well as BF rated, it has a leakage current ...
  • Cloud-based design and evaluation platform
    27 February 2019, Altron Arrow, Design Automation
    ON Semiconductor has rolled out Strata Developer Studio, a cloud-based development platform that provides a seamless, personalised and secure environment for engineers to evaluate and design with ON Semiconductor ...
  • AVR MCUs get beta support in MPLAB X
    30 January 2019, Avnet South Africa, Design Automation
    Microchip Technology recently announced the release of MPLAB X integrated development environment (IDE) version 5.05, which beta supports the majority of AVR microcontrollers (MCUs). This release will ...
  • Extruded aluminium enclosures
    30 January 2019, Sivan Electronic Supplies, Enclosures, Racks, Cabinets & Panel Products
    Gainta’s ALUG7XX range of extruded aluminium enclosures encompasses different sizes, with suitable lengths for indoor desktop devices or outdoor wall-mounting junction/control box use. They come in five ...

Technews Publishing (Pty) Ltd
1st Floor, Stabilitas House
265 Kent Ave, Randburg, 2194
South Africa
Publications by Technews
Dataweek Electronics & Communications Technology
Electronics Buyers’ Guide (EBG)

Hi-Tech Security Solutions
Hi-Tech Security Business Directory

Motion Control in Southern Africa
Motion Control Buyers’ Guide (MCBG)

South African Instrumentation & Control
South African Instrumentation & Control Buyers’ Guide (IBG)
Terms & conditions of use, including privacy policy
PAIA Manual


    Classic | Mobile

Copyright © Technews Publishing (Pty) Ltd. All rights reserved.