Programming four ST7 CPUs in parallel

[zsavov]

Posted on May 29, 2009 at 05:11

Programming four ST7 CPUs in parallel

[zsavov]

Posted on April 08, 2009 at 10:43

Hi,

In my device I have four CPUs (ST72F325). They share supply, they get some signals from the same source and they all get clock from the same external clock source(crystal-based). They do not communicate to each other and they operate independently of each other. As the space on the board is at premium I decided to use one common socket for in-circuit programming. The only problem is how to enable one CPU only and disable the remaining three when programming them with the RLink. The solution I have in mind is this:

If I want to program CPU#1 I connect its RESET pin to the ICP socket (so the RLink will control it) and connect the RESET pins of the remaining CPUs to ground (so they do nothing and do NOT interfere with programming CPU#1). I attached a circuit in JPG format (the irrelevant parts have been removed).

I wonder if someone had any experience with a matter like this and tell me if this will work.

Thank you

zsavovAThotmail.com

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Attachments :

Schematics.JPG : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0BV&d=%2Fa%2F0X0000000bUv%2Fm1dAQSMhe7yygVv7fMNKghAybp13pnHF2ba1fWSRV98&asPdf=false

[rajan]

Posted on May 29, 2009 at 05:11

Use two buffer ICs like 245 which have two Output Enable signals.You will need 4 switch which have to be operated manually!