Lpc2000

I've had a few queries in regards to SD card initialization in SPI
mode. For anyone who is interested I have included a dump of the SPI
activity during an init. There are two examples, the first with a
SANDISK 512M Ultra, and the second with a generic 128M SD.

The SD & FAT code are written in a Forth that I have written for the
LPC2000s. Since this is not everyones cup of tea, I have included a
simple dump of the activity of the SD interface. Comments are as
normal and bytes that are read are prefixed with "r", those that are
writes are prefixed with "w". All bytes are in hex.

Although it is possible to issue a CMD1 following a CMD0, the SANDISK
SD CARD product manual states that ACMD41 should be used. This avoids
confusion with MMC cards but read what SANDISK have to say in section
5.8. Apparently ACMD1 is an illegal command for the thin cards in SPI
mode.

The dummy read at the start of the CMD is just to make sure that the
SD interface is synchronized etc. This is easier than putting dummy
reads at the end of transfers .

One thing that didn't show-up on the 128M cards but did on the 512M
was when I was accessing high memory around 300MBs up. I would find
that the data token response on a read block request was taking a lot
longer. I had to either introduce a delay of 1ms in each loop or
increase the retry counter from 8 to 4000!!! (I am running at 16Mhz
SPI rate).

Hope this is useful.

*Peter*

;*************************** SD CARD INITIALIZATION
************************


; *** Initialize a Sandisk 512M SD CARD ***

VDD OFF
CS ON
5ms
VDD ON
1ms

; Dummy clocks
CS ON
rFF rFF rFF rFF rFF rFF rFF rFF rFF rFF
CS OFF
wFF wFF

; CS is asserted to ensure that all interfaces lines are at VSS (no
power whatsoever)
CS ON
rFF rFF
CS OFF
5ms

; CMD0
CS ON
rFF w40 w00 w00 w00 w00 w95 rFF r01

; ACMD41 until response = 0
CS ON
rFF w77 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w69 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w77 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w69 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w77 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w69 w00 w00 w00 w00 w95 rFF r00

; Read OCR
CS ON
rFF w7A w00 w00 w00 w00 w95 rFF r00
r80 rFF r80 r00

; Read CID
CS ON
rFF w4A w00 w00 w00 w00 w95 rFF rFF r00
rFE
r03 r53 r44 r53 r44 r35 r31 r32 r57 r50
r3D r11 r89 r00 r51 r5F rFD rA2 rFF

; Read CSD
CS ON
rFF w49 w00 w00 w00 w00 w95 rFF rFF r00
rFE
r00 r26 r00 r32 r1F r59 r83 rC7 rBE rFB
r4F rFF r92 r40 r40 r3F rF9 rAF rFF
CS OFF





; *** Initialize a generic 128M SD CARD ***

VDD OFF

CS ON
5ms
VDD ON
1ms
CS ON
rFF rFF rFF rFF rFF rFF rFF rFF rFF rFF
CS OFF
wFF wFF
CS ON
rFF rFF
CS OFF
5ms

; CMD0
CS ON
rFF w40 w00 w00 w00 w00 w95 rFF r01

; ACMD41
CS ON
rFF w77 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w69 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w77 w00 w00 w00 w00 w95 rFF r01
CS ON
rFF w69 w00 w00 w00 w00 w95 rFF r00

; Read OCR
CS ON
rFF w7A w00 w00 w00 w00 w95 rFF r00
r80 rFF r80 r00

; Read CID
CS ON
rFF w4A w00 w00 w00 w00 w95 rFF r00
rFF rFE
r04 r00 r00 r44 r30 r35 r30 r37 r00 r02
r02 r8E r69 r00 r48 rFB r6E r4B rFF

; Read CSD
CS ON
rFF w49 w00 w00 w00 w00 w95 rFF r00
rFF rFE
r00 r7F r00 r32 r1F r59 r83 rC9 rF6 rDA
r3F r9F r96 r60 r00 r2D r76 rB7 rFF
CS OFF


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P.S. Resent this message as my SMTP server seems to have a problem.