The /TRST signal resets the JTAG tap controller. The /TRST signal should help low in a system operating in normal mode with no equipment attached to the JTAG port. If allowed to float the part can end up accidently capturing invalid signals via the JTAG interface and placing the part in a debug mode when this is not intended. Thanks.

- Bill

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From: c...@mails.tsinghua.edu.cn [mailto:c...@mails.tsinghua.edu.cn]
Sent: Friday, January 03, 2003 11:16 PM
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Subject: [motoroladsp] ask help about the TRST pin of dsp56f807

In normal mode,the /TRST pin should be pulled high, and only when entering debug mode,should this pin asserted with /RESET signal.But I notice the schematics coming with the DSP56f807EVM User's manual,that the signal J_TRST is pulled low,which means the output pin TRST which is designed as RST=/POR * /J_TRST should be normally low,if /POR is left floated,can anyone explain it? Wish every one a happy New year!

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In normal mode,the /TRST pin should be pulled high, and only when entering debug mode,should this pin asserted with /RESET signal.But I notice the schematics coming with the DSP56f807EVM User's manual,that the signal J_TRST is pulled low,which means the output pin TRST which is designed as RST=/POR * /J_TRST should be normally low,if /POR is left floated,can anyone explain it? Wish every one a happy New year!