[iPAQ] 16-bit SRAM access on ipaq expansion pack(small correction)

Hi.

Just a small correction in my previous email
(indicated by ^^). Sorry for that.

best wishes,
-- prabhat
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Prabhat Avasare avasare@imec.be
Fri, 01 Feb 2002 19:54:30 +0100

Hi.

In our expansion pack for ipaq 3760, we were trying
to do a simple SRAM access on MCS2 for 16-bit data.
There were two problems with that :-

1. If we try to access expansion pack memory as
   (unsigned short*) in our C program(like
    *((unsigned short*)(EXAPNSION_MEM_BASE)) = 0x1234;),
    ^^
   arm-linux-gcc converts it into two instructions
   (hence more cycles) of STRB(byte store) each.
   For (int*) though, only one STR instruction is
   generated. Is this normal or are we missing something?

2. When connected to logic analyser we see that,
   in case of (int*) access, only D15-8 are filled
   with correct values, but D7-0 are all zeroes.
   I read in sa1100 developer's manual that nCAS[3-0]
   enable corresponding bytes during memory accesses.
   Has that got anything to do with this? If yes,
   how do I turn nCAS[] on?

Best wishes,
-- prabhat
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Received on Sun Feb 3 07:21:27 2002