Lpc2103

Debugging and Programming .... ok i usually would just copy the data from this schematic (TOP RIGHT SIDE)

https://www.olimex.com/dev/images/lpc-h2103-sch.gif

but im wondering why the heck are so many resistors needed on the JTAG part ?

I was reading the User Manual and it states to enter debug mode i need to have RTCK pulled HIGH .... and DBGSEL should be also HIGH

In the schematic:

RTCK is pulled high - OK i get this!
TRST is pulled high ( WHY ? )
TMS is pulled high ( WHY ? )
TCK is pulled low ( WHY ? )
TDI is pulled high ( WHY ? )
TDO is pulled high ( WHY ? )


Can someone help me out here. I dont want to make PCBs and omit them and it doesnt work... im not rich

It would make PCB design easier...

I dont plan to use the PINs for anything else besides debugging.

Pullups and pulldowns to prevent bus float? I question the use of 100K resistors.

ah ... so i guess its needed then.. sucks tho.. waste of space and parts really... but important heh

But a string of resistors on a board looks so cool.

heh so true

ARM standard JTAG specifies these 100k pullups. Olimex tends to make safe designs. I've added the pullups on all my designs as well.

Hey Mark!! hows it going.. im not trying to sound wrong here but you got link to JTAG Standards? I just never found anything on google so i asked here

You can check here under the uLink hardware spec:
ARM Information Center

Definition of the signals plus pullup/pull down spec:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0517b/Cjaeccji.html

10k or 100k?
ARM Information Center

You ROCK!!! thanks a ton! I printed it as a PDF for future reference.. Thanks again

I also just remembered that the LPC210x has a bootloader with ISP use so i can omit the JTAG completely on some boards. Since i use the LPC-H2103 Header board from olimex to debug anyway...

...When i make a PCB i can just program it since debugging is complete ... if i need to make changes i can just use header board to test again and then alter code and reprogram via ISP...

Already tested the bootloader on the LPC2103 with a CP2102 USB to Serial Connection and works 100%