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RE: Memory and wiring
1. You should rely on the library functions for alloction/deallocation
of memory. Applications with their own memory handlers tend to
allocate a huge chunk of memory to be "safe". The Etrax 100 has
no MMU and this means that this must be allocated in "real" memory.
A few application unnecessary large memory request may exhaust
2. On our web there is example software for a LCD connected to a
There are three ways to control the parallel port:
automatic - Etrax handles handshaking. Used to connect printers.
manual - Software has control of the handshaking signals. This
is used by the LCD driver.
general IO - Software has full control of all pins on the
To protect Etrax you can add a buffer (e.g. 74245) on the signals
3. JFFS has a garbage collector that also performs some
defragmentation when it runs.
Behalf Of David Pettersson
Sent: Sunday, September 24, 2000 10:09 AM
Subject: Memory and wiring
After having played about with the labcard, I feel I ready to do some
serious stuff with it. First of all, I'd like to know what you suggest
when it comes to memory management; Should I rely on the library functions
for allocating/deallocating memory, or should I simply request a chunk
of memory and use an internal memory manager in the application?
Secondly, is there any suggested way to wire stuff to the card, using
the lp pins? I don't want to risk frying any part of the card, so
I was wondering if you had some recommended way of wiring things to these
pins, or maybe even a schematic?
And finally, when reading/writing to the flash memory, how does the
driver handle fragmenting? Will it become heavily fragmented after
a while, and will it be defragmented at any time?
I'd appreciate any help I can get regarding the above,
David Pettersson email@example.com
PGP key available on request.