LPC1111 "JTAG" Signals

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LPC1111 "JTAG" Signals

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by richas on Wed Feb 17 15:19:00 MST 2010
I am trying to specify the JTAG pinout for our layout guy for the LPC1111 in QFN.  First a basic question, this debug interface is commonly referred to as a "JTAG" interface yet, the more I look at it the more it looks like something called "SWD".  I am used to the ARM7 devices with a more typical JTAG interface.  Maybe someone can clear that up for me.

I am using a 2x5 male header as found on the LPC-Link board.  I have it pinned out as follows:
1  3.3V
2  pin 22 (tms)
3  gnd
4  pin 19 (tck)
5  gnd
6  pin 23 (tdo)
7 nc
8  pin 21 (tdi)
9  gnd
10  pin 2 (reset)

Perhaps someone has done this and could verify my connections.

Thanks

Rich
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9 Replies

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by annodomini2 on Thu Feb 18 08:21:05 MST 2010

Quote: NXP_USA
...but not with the LPCXpresso free toolchain because it always resets the part and reprograms it when entering debug. ...




Are you talking about the DFU operations of the debugger or the flash on the target device?
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by igorsk on Wed Feb 17 17:25:08 MST 2010

Quote: richas
??????


Sorry, I should have been more clear. I was replying to
"...it always resets the part and reprograms it when entering debug."
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by richas on Wed Feb 17 17:21:14 MST 2010

Quote: igorsk
Won't constant reprogramming wear down the flash? Is there any way to turn off this "feature"?



??????
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by igorsk on Wed Feb 17 17:19:01 MST 2010
Won't constant reprogramming wear down the flash? Is there any way to turn off this "feature"?
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by NXP_USA on Wed Feb 17 16:43:54 MST 2010

Quote: richas
I tried disconnecting SWO, reset, and the pullup on reset.  (These are R31, R32, and R33 on the LPCxpresso board)

Debug did not function.  It will work without SWO (what IS SWO?) or the pullup on reset but not without the reset signal itself.


Rich



Which pins are needed depends on what debug functionality is required. It is possible to connect to the part with just SWD and ground, but not with the LPCXpresso free toolchain because it always resets the part and reprograms it when entering debug. If you wish to use Trace features which are in the full Red Suite/Red Probe tools but not the free LPCXpresso tool, then you would need to connect SWO as well.

-NXP
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by richas on Wed Feb 17 16:21:50 MST 2010

Quote: igorsk
LPCXpresso board does connect pin 28 to SWO (Serial Wire Output) but there's actually no SWO functionality on the chip. I guess they did it just to keep the layout the same as on 13xx. Either way, both SWO and RESET are not part of the SWD protocol, though they still might be useful for debugging.



I tried disconnecting SWO, reset, and the pullup on reset.  (These are R31, R32, and R33 on the LPCxpresso board)

Debug did not function.  It will work without SWO (what IS SWO?) or the pullup on reset but not without the reset signal itself.


Rich
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by igorsk on Wed Feb 17 15:45:02 MST 2010
LPCXpresso board does connect pin 28 to SWO (Serial Wire Output) but there's actually no SWO functionality on the chip. I guess they did it just to keep the layout the same as on 13xx. Either way, both SWO and RESET are not part of the SWD protocol, though they still might be useful for debugging.
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by richas on Wed Feb 17 15:40:33 MST 2010
The lpc-link board breaks out four signals while Microbuilder only two.  More confusion....

Rich
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by igorsk on Wed Feb 17 15:37:08 MST 2010
As just posted here, LPC11xx does not support full four-pin JTAG but only two-pin SWD. So you need to break out only SWCLK (TCK) and SWDIO (TMS).
Check LPCXpresso schematics to see how they did it. There is also a (beta) design from Microbuilder.
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