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SWCLK - External pull-down? LPC1549, SWD

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by Terje on Mon Nov 30 14:32:21 MST 2015
In the recommended design (fig 49. in the datasheet) it is shown an external pull-down on the SWCLK pin. However, in the user manual, table 628 it says that SWCLK is internally pulled up. On the page "Design Considerations for Debug" (https://www.lpcware.com/content/faq/lpcxpresso/debug-design) it says the following:Note for TCK/SWCLK, although a pull-down is recommended, you can alternatively use a pull-up. The main thing is that it does not float. Note in particular that if the MCU provides an internal pull-up on this signal, then adding an external pull-down on the board is not recommended. What is correct? Should it be pulled up or down?

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