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UART, Flash and other Questions ?

Started by Lasse Madsen April 16, 2004
Hi all ...

I have an application where I would like to use a GPRS modem coupled
directly to the UART1's modem interface etc...
I have never worked with such a full modem interface before (RTS,CTS,DTR
etc...) so I was curious ... Do one have to control the modem signals in
software or does the modem control this in hardware (for example .. if the
modem asks the UART to stop transmitting i guess the uart stops until it can
see that the signal isnt present any more and then resumes automatically as
long as the FIFO is full ?)

Another question is ....

I have a commercial FAT12/16/32 file system I would like to implent into the
2106 it occupies about 40KB of code in an AvR 8bit processor do you have any
idea what that would relate to (in KB) in the LPC ? (disregarding the
compilers optimization) what I mean is ... is 40KB code in an AvR the same
as 40KB code in an LPC ARM ?

Another this ...

Has anyone tried to interface a MMC/SD card to the LPC ... i know its
possible ofcause but what im thinking of is if its possible to use the /SS
pin to drive the ChipSelect (CS) on the SD card (can the /SS pin be
configured as an output and controlled in software?)

regards
lasse madsen



An Engineer's Guide to the LPC2100 Series

>
> Another question is ....
>
> I have a commercial FAT12/16/32 file system I would like to
implent into the
> 2106 it occupies about 40KB of code in an AvR 8bit processor do
you have any
> idea what that would relate to (in KB) in the LPC ? (disregarding
the
> compilers optimization) what I mean is ... is 40KB code in an AvR
the same
> as 40KB code in an LPC ARM ?

This may or may not help, its the only 8-bit uP to ARM/Thumb
comparison I have to hand.

In another lifetime I had to find a way to remove 80%fsd spikes from
a flammable gas detector, with less than 200 bytes remaining in the
ROM space of an 8051 device.

The method I used recorded four history values, and selected the
closest to the currently displayed reading as the next value to
display. This worked nicely and also clamped a wandering-zero
problem. This is obviously a very small example but uses table
indexing, loops and 16-bit comparisons.

Compiling the function with an early version of Keil's C51 produced
a 220 byte lump of code. Three hours work produced hand-optimized
assembly code generating 108 bytes of code.

Some years later, purely for personal interest I compiled the
original C using the ARM SDT200 compiler - 120 bytes of code.
Compiling as Thumb code gave 86 bytes of code.

Unless you're doing very simple bit or byte copying with no
arithmetic and very little decision-making, I would suspect that the
ARM, or certainly the Thumb code would be more compact than code for
an accumulator-bound 8-bit micro.

Peter.