KEIL recommends to add pull up on SWDIO and pull down on SWCLK unless the device already include them internally. see below. Should I add them or not to my board with LPC54S018M?
ULINK2 User's Guide: Target Connectors
Hi, Bob,
Both of the SWDIO and SWDCLK signals have on-chip pull-up resistors as the following Fig from UM11155.pdf, so I think it is okay not to use any any external resistors.
But I have checked the schematics of LPC540xx, the SWDIO pin is connected with a 100K ohm resistor, so I think you can connect a 100K ohm resistor or not for the SWDIO pin, for the SWDCLK, it is unnecessary to connect any resistor.
Hope it can help you
BR
XiangJun Rong
Hi, Bob,
Both of the SWDIO and SWDCLK signals have on-chip pull-up resistors as the following Fig from UM11155.pdf, so I think it is okay not to use any any external resistors.
But I have checked the schematics of LPC540xx, the SWDIO pin is connected with a 100K ohm resistor, so I think you can connect a 100K ohm resistor or not for the SWDIO pin, for the SWDCLK, it is unnecessary to connect any resistor.
Hope it can help you
BR
XiangJun Rong
