Notes concerning LPC43xx and OpenOCD

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    The LPC43xx seems to be pretty finicky when it comes to its JTAG. interface. Here are a few things that I found helped in getting the LPC and OpenOCD to talk,

    • I use a BusBlaster. The new interfaces/ftdi/dp_busblaster.cfg configuration uses OpenOCD’s new FTDI driver which seems to be much more reliable than the old interfaces/busblaster.cfg configuration.

    • The M0 target seems to screw up halt. Workaround by disabling in target/lpc4350.cfg. (TODO: check whether this is still necessary)

    • Even then, reset halt appears to be broken. This appears to be due too SRST being asserted twice. Work around by commenting out,

    	foreach t $targets {
		# C code needs to know if we expect to 'halt'
		if {[jtag tapisenabled [$t cget -chain-position]]} {
			$t arp_reset assert $halt
		}
	}

    and,

    	foreach t $targets {
		# Again, de-assert code needs to know if we 'halt'
		if {[jtag tapisenabled [$t cget -chain-position]]} {
			$t arp_reset deassert $halt
		}
	}

    in target/startup.tcl

    • the first use of GDB’s load command will jump into ROM