Lpc2000

Leon Heller wrote:

> ----- Original Message ----- 
> From: "martin de lange" <martin_de_lange@...>
> To: <lpc2100@yahoogroups.com>
> Sent: Tuesday, February 03, 2004 8:23 AM
> Subject: Re: [lpc2100] JTAG port
> 
> 
> 
>>Do you mean that one would sometimes use the one JTAG port and at other
>>times use the other accoording to which I/O you wanted to use ?
> 
> 
> Yes, it's mentioned in the data sheet.
> 
> 
>>I have also seen at times that users at times cannot get the second port
> 
> to
> 
>>work for debug and or flashing.
> 
> 
> I think that Philips has stated that the second JTAG port cannot be used for
> programming, only debug.
> 

Where? That's a pretty important piece of info. If that's the case then 
this part isn't as useful as it looks at first glance. If you need the 
primary JTAG for debug and programming then you lose those pins and the 
trace pins (from my understanding).

Sharing JTAG pins with I/O is an understandable practice from the 
manufacturer's standpoint, but from mine it makes designing things alot 
more difficult -- its pretty hard to assign any useful function to the 
pins that are used by the JTAG. You're almost better off programming it 
via the serial port and using 1-line diagnostics to debug like you have 
to do on the PIC <G>.

Brian


-- 
-----------------------------------------------------
Brian C. Lane (W7BCL)                      Programmer
www.shinemicro.com   RF, DSP & Microcontroller Design