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AR# 52847

Zynq-7000 Board Design - Sequencing for SRST and POR Signals

描述

Zynq based boards should be laid out such that SRST and POR signals are asserted in a specific order.

解决方案

Designers should ensure that the SRST signal is de-asserted before the POR signal is de-asserted when laying out Zynq-7000 boards. This issue is related to (Xilinx Answer 52013).

Frequently Asked Questions About This Recommendation

Q1. Does this recommendation only affect initial power on?
A1. No, this also applies to reset sequences when the system is already up and running.

Q2. Can PS_SRST_B be pulled High if it is not used?
A2. Yes. Pulling PS_SRST_B High is the de-asserted state, so this would mean that it does not conflict with PS_POR_B.

Q3. Does this mean that PS_SRST_B cannot be asserted when PS_POR_B is asserted?
A3. No, PS_SRST_B can be asserted at the same time as PS_POR_B but PS_POR_B must be the last signal that is asserted.

Q4. How does this recommendation affect the release order of PS_SRST_B and PS_POR_B?
A4. PS_POR_B should be the last signal de-asserted and PS_SRST_B should not re-assert until after the BootROM is complete.

Q5. Does PS_SRST_B have to connect to an external sequencer/supervisor device?
A5. No, there is not a requirement to use a sequencer/supervisor, but it makes design easier and more straightforward. Managing this sequence can be done manually as long as the designer is careful to follow the recommendations above.

链接问答记录

主要问答记录

Answer Number 问答标题 问题版本 已解决问题的版本
52539 Zynq-7000 AP SoC - Board Design N/A N/A

相关答复记录

Answer Number 问答标题 问题版本 已解决问题的版本
52013 Zynq-7000 AP SoC, Boot Sys - PS_SRST_B asserted during a POR boot does not result in a secure lockdown N/A N/A
AR# 52847
日期 06/03/2013
状态 Active
Type 综合文章
器件
  • Zynq-7000
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