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10 years, 5 months ago.
LPC1768 MCU pull up resistor reset with jtag - safe?
Hi,
I'm creating a PCB with the LPC1768 MCU. On the ref schematic provided on here, there is no pull-up resistor connected to pin 17 of the MCU, so it will be floating until it is driven.
Is this the normal setup?
I want to place a button system to reset the device, I would do the normal thing of applying a pull-up resistor with the switch connecting ground to the pin, but I haven't seen it anywhere and I'm not sure if it would affect the JTAG programmer when it is connected, as the reset pin is used for that.
The manual does not say it has it's own internal pull-up resistor, or recommend an external one be applied.
Does anyone have any thoughts?
Thanks, Adam.
1 Answer
10 years, 5 months ago.
You need a pullup (typically 10K). External JTAG will be fine with that. I have reviewed several other board schematics of LPC1768 systems and all use pullup. Checkout for example the schematic of the Landtiger board here.