Minimum connections to talk to LPC4330 (100BGA) via SWD

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by Zuofu on Thu Jul 11 23:04:12 MST 2013


I have designed a simple 2 layer board with a minimum of connections for the LPC4330. It basically only has USB, SD, and a couple of SGPIO...


However, when I build the board, I cannot access the chip via SWD (using uLINK-ME). My understanding is that only SWDIO/SWCLK and !RESET have to be connected to the 10-pin header (as well as all VCC/GND lines, and DBGEN pulled high). The chip draws a reasonable 10mA or so (running no code), which leads me to suggest at least power and ground are not shorting and that some of the power balls should be connected. I've attached my (somewhat disorganized) schematic. The debugging stuff is on the lower right. Am I missing something? Is it necessary to connect TDI even if using SWD? I noticed that the user manual for the LPC4330 has pullups on the SWD pins, but the LPC4330-Xplorer schematic does not...is there something else I'm missing?


Original Attachment has been moved to: schematic.zip