I'm curious what exactly DBGSEL does. From the user manual:

Debug Select: When LOW, the part operates normally. When HIGH, debug mode is entered. Input pin with internal pull-down.

So what exactly is Debug Mode? From user manual:

The Debug mode connects the JTAG pins to the embedded ICE for program debugging using an emulator or other development tool.

Ok. So, if I spin a board with both RTCK and DBGSEL tied high, I will always have JTAG access if needed on the primary JTAG port. I will lose pins 17-31 (no big deal, I don't have huge I/O requirements). I can program the device and execute the code. Other than the JTAG being able to control the device, is there anything else functionally different? If I ship the board off with a program installed, will it function the same as if DBGSEL was tied low?

Thank you for any help.

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Hi,

DBGEN = high means boundary scan mode for the MCU. It's used in fab to validate
the MCU functions (quality control process), and not meant for user to play
around with it.

Whether you need the JTAG or not, always put 'DBGEN = low'. Otherwise, your MCU
will not operate normally.

Regards,
-daniel
----- Original Message ----
From: laphi81
To: l...
Sent: Sat, December 4, 2010 1:56:54 AM
Subject: [lpc2000] DBGSEL and LPC210x

I'm curious what exactly DBGSEL does. From the user manual:

Debug Select: When LOW, the part operates normally. When HIGH, debug mode is
entered. Input pin with internal pull-down.

So what exactly is Debug Mode? From user manual:

The Debug mode connects the JTAG pins to the embedded ICE for program debugging
using an emulator or other development tool.

Ok. So, if I spin a board with both RTCK and DBGSEL tied high, I will always
have JTAG access if needed on the primary JTAG port. I will lose pins 17-31 (no
big deal, I don't have huge I/O requirements). I can program the device and
execute the code. Other than the JTAG being able to control the device, is
there anything else functionally different? If I ship the board off with a
program installed, will it function the same as if DBGSEL was tied low?

Thank you for any help.

Start a New Thread

Whoops...Th op asked for 'DBGSEL', I answered 'DBGEN'...sorry..

I don't have any experience for LPC21xx, but reading its User Manual, it seems
like DBGSEL overrides PCB for P0.27-P0.3. So, there shouldn't be any
interference with other pins. But IMHO, you'd probably want to disable JTAG
access for end user products, unless you want it to be available to be copied
by competitors.

Regards,
-daniel
----- Original Message ----
From: Daniel Widyanto
To: l...
Sent: Sat, December 4, 2010 11:20:55 AM
Subject: Re: [lpc2000] DBGSEL and LPC210x

Hi,

DBGEN = high means boundary scan mode for the MCU. It's used in fab to validate
the MCU functions (quality control process), and not meant for user to play
around with it.

Whether you need the JTAG or not, always put 'DBGEN = low'. Otherwise, your MCU
will not operate normally.

Regards,
-daniel
----- Original Message ----
From: laphi81
To: l...
Sent: Sat, December 4, 2010 1:56:54 AM
Subject: [lpc2000] DBGSEL and LPC210x

I'm curious what exactly DBGSEL does. From the user manual:

Debug Select: When LOW, the part operates normally. When HIGH, debug mode is
entered. Input pin with internal pull-down.

So what exactly is Debug Mode? From user manual:

The Debug mode connects the JTAG pins to the embedded ICE for program debugging
using an emulator or other development tool.

Ok. So, if I spin a board with both RTCK and DBGSEL tied high, I will always
have JTAG access if needed on the primary JTAG port. I will lose pins 17-31 (no

big deal, I don't have huge I/O requirements). I can program the device and
execute the code. Other than the JTAG being able to control the device, is
there anything else functionally different? If I ship the board off with a
program installed, will it function the same as if DBGSEL was tied low?

Thank you for any help.

Start a New Thread