
89S /AV R(90S )
S oc ket S tealer
Equinox Technologies UK Limited
UK Contact Details
3 Atlas House, St. Georges Square, Bolton BL1 2HB England
Tel: +44 (0) 1204 529000 Fax: +44 (0) 1204 535555
E-mail:
sales@equinox-tech.com
Web site:
www.equinox-tech.com
US/Canada Contact Numbers
Tel: 1-800-216-1777 Fax: 1-800-234-0941
Document Version 1.0
Atmel 89S/AVR(90S) Socket Stealer
1. Introduction
1.1 Overview
With the pressing timescales of modern-day electronic design, developers are often faced with the task of designing unproven
circuitry onto a circuit board, only to find out that the design doesn’t work as expected when the PCB arrives back from
manufacture. Implementing in-system programming (ISP) of Atmel microcontrollers for the first time on a circuit board is
fraught with pitfalls as there are considerations such as choice of ISP header, power supply constraints, SPI contention
problems, Reset timing problems etc. Debugging of such problems can be very time consuming as it is not possible to isolate
just one cause.
In light of all the potential problems with implementing ISP, Equinox have come up with a range of ‘ISP Socket Stealer
Modules’ which convert an existing non-ISP compatible target board into a working ISP solution by simply plugging the
module into the microcontroller socket on the target board. The ‘Socket Stealer’ incorporates all the necessary ISP hardware
including ISP microcontroller, Reset circuit, ISP programmer connector and crystal. An ISP programmer such as the Equinox
‘Micro-ISP’ or ‘Activ8r’ connects to the ISP connector on the module and allows serial downloading/uploading of data from
the module. The advanced electronic circuitry on-board the ‘Socket Stealer’ isolates all relevant programming lines during the
ISP process ensuring that even with SPI bus contention, the microcontroller will still be able to be successfully programmed. It
is also possible to leave the ‘Socket Stealer’ in the target socket even when a programmer is not connected making field code
updates possible.
The diagram below shows how the microcontroller plugs into the Socket Stealer which in turn plugs into a target board. A
version of the Socket Stealer is also available that will allow it to plug into a PLCC-44 socket on the target board.