Hello,

Here time to time people ask about ISP (In System Programming) of Atmel AT89Sx devices. I checked through 8052.com and found that there are a lot of schematics and software indicated there. Most of them are third-party and out-dated ones. As well, there are many reports about that "it does not work", "it does not support" etc.

From other side, there is Atmel firmware called AT89ISP. This software supports all Atmel derivatives compatible with ISP-via-SPI mode even newest which are not produced yet (=

Atmel has published AT89ISP Programmer Cable but this document shows the header pinout only. Which parts are used inside device and how it is connected to LPT port -- these details are not described there. Just a note: AT89ISP cable costs about 50 USD here.

Now there is a little history.
Recently I was asked to use Atmel CPLD into a project. Well, I visited Atmel site checking for a programmer. And I found its schematic there. I assembled it and self-made cable is being worked good for now. Looking on its schematic, one idea came to me. So I connected this cable to a board with AT89S2051 assembled on it. This board implements ISP of the MCU according Atmel reference design (with 10-pin header described in the document I mentioned above). I downloaded and installed Atmel AT89ISP software and its last update from their site, then did power-on and run AT89ISP software.

Result:



Indeed, it works.

Finally, it seems we do close the question about ISP-via-SPI for Atmel derivatives.
Here is free firmware software from Atmel:
http://www.atmel.com/dyn/products/tools_card.asp?tool_id=2877
Here is free schematic of the cable:
http://www.atmel.com/dyn/resources/prod_documents/isp_C_v5.PDF
Yes, it says about schematic "Atmel-ISP Download Cable Schematic. This document contains the schematic diagram for the Atmel-ISP Download Cable (P/N ATDH1150VPC) used for In-System Programming (ISP) of Atmel ISP CPLDs." Seems it works with AT89Sx derivatives same good (=
Last note about schematic: it is not obligatory to assembly voltage detection - just connect ERROR to Vcc via 4K7 as it is done for 12 and 13 pins of LPT port.

Hope Atmel will not claim me for this post -- all referenced materials are published by Atmel themself and are free for download yet.

Regards,
Oleg

P.S. Could you - Steve or Craig, increase space of my homepage, please? Thanks.