Lpc2103

[AtomSoft]

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.

 

[upand_at_them]

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

 

[AtomSoft]

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

 

[upand_at_them]

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

 

[AtomSoft]

heh so true

 

[DirtyLude]

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

 

[AtomSoft]

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

 

[DirtyLude]

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

 

[DirtyLude]

10k or 100k?
ARM Information Center

 

[AtomSoft]

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

 

[AtomSoft]

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%