Lpc2000

--- In lpc2000@yahoogroups.com, "jayasooriah" <jayasooriah@...> 
wrote:
> I like to know if you think any other ARM licensee is worse.

I'm not saying it's worse, but see the OKI ARM7 MCUs for a very 
similar device that handles booting and programming differently. 
They use a combination of external (dedicated) pins and internal 
register settings to select the boot mode (e.g. to re-flash etc.). 
Personally, I find the Philips approach simpler, easier to use and 
more flexible. It's a matter of choice though: I don't think either 
approach is seriously flawed as you state.

> I agree it is design issue.  I call it a defect in that the design
> because it did not take into account of the kind requirements one 
user
> had -- where the UART0 is operated in slave mode.
> 

Can you explain what you mean by slave mode? As a standard 
asynchronous UART, the LPC2xxx UARTs don't have any concept of 
master/slave as far as I'm aware.

> To fix this defect, one can change the software (in boot loader) or
> add hardware to work around.  The extent to which people had 
discuss
> about hardware options was what I referred to as intimidating.

Again, personally I'd agree with Robert and think the boot loader 
select pin should be dedicated to that function. However, then 
people would complain it's using up a pin that could be shared. The 
DCD clash is inconvenient if you don't spot the issue at the start 
(maybe an extra warning in the manual would help here?), but it's 
perfectly possible to design a reliable system without extra 
hardware if you understand the issue. It's certainly not necessary 
to change the boot loader software, which as I've already pointed 
out is an extremely poor strategy.

> Boot loader should be simple -- just to provide bare minimum to 
gain
> control when there is no firmware, not to provide virtual flash
> abstractions, external bus configuration or software protection.
> 

See the OKI parts for an alternative. I guess it's a matter of 
opinion on how these things are implemented. They each have their 
pros and cons. I guess if there was an optimum design that everyone 
agreed on, all parts would be the same!

Brendan