Lpc2000

Thanks for the good info guys.  I am looking at the assembly code 
for changing the SPI registers.  It's just a couple simple lines:

165: S0SPCR = 0x0C24;  // Changed to 12-bits per transfer for LCD 
format. 
0x0000215E  2124      MOV       R1,#0x24
0x00002160  4829      LDR       R0,[PC,#0x00A4]
0x00002162  7001      STRB      R1,[R0,#0x00]

you can see that the assembly code just puts the 0x24 in R1, the 
upper byte is gone?  Why would it do this?  I am using the memory 
and register watch windows as I step thru this code.  It is very 
clear to see that the upper byte is just ignored.  It's like the 
compiler thinks the S0SPCR register is 8-bits instead of 16. 
Ah..............
That just made me look in the LPC21xx.h file where:
#define S0SPCR         (*((volatile unsigned char *) 0xE0020000))
yes, it is defined as a char so it will only look at the first byte.
So I changed the char to short.
NO......it still does not work.????

Yes, I am using a GPIO for SEL.  That seems to work fine, I just 
can't change the size of the SPI buffer?

-Dave





--- In lpc2000@yahoogroups.com, Rob Jansen <rob@m...> wrote:
> Dave,
> 
> > So I configured the SPI control register to operate in this
> > mode.
> >
> > S0SPCR      =   0x0C24;
> > ...
> > However, when I step thru my code, and look at the S0SPCR 
register,
> > it
> > is written with a 0x0424!!!!!!!!!!!!!
> 
> Strange, I tried this on my 2138 and there it all works (to say, 
writing 
> to the register works).
> Should work on the 2131 also.
> I wrote a small program 
> (http://www.myvoice.nl/electronics/files/io-test.zip) to read and 
write 
> registers and memory - served me well a few times. typing "w 
e0020000 
> c24" will write to the memory location and read it back 
afterwards. 
> Typing "r e0020000" will read the memory. I used this program 
myself 
> already a few times - as soon as I don't trust the hardware I 
start 
> poking around in the chip ...
> 
> If writing to the register works, can you singlestep through the 
> assembly code (that's an istep in ARM AXD) or at least see the 
assembly 
> code and the CPU registers?
> 
> > Also I am new to LCD's never programmed one before, the format 
of the
> > data looks really strange.  If anybody knows some good tricks for
> > interfacing an LCD with a serial interface, I would be grateful.
> 
> I checked out the controller spec 
> (http://mxhaard.free.fr/spca50x/Doc/LCD/1621.PDF ?) and the 
interface 
> indeed is a bit strange compared to the I2C displays I am used to. 
Only 
> the command mode uses 12 bits, it you write data to the LCD you 
should 
> switch to 14 bits mode.
> 
> It should however be fairly easy, CS to a GPIO pin, WR to SCK and 
the 
> data pin of the LCD to MOSI. Configure CPOL=1 and CPHA=1 (see 213x 
user 
> manual), LSBF=0. This gives SOSPCR =  0x0C6E to send the commands 
and 
> after initialization switch over to 0xE6E for 14 bits to send the 
first 
> 4 databits to a given address. Sequential datawrites should then 
be done 
> in 8 bits mode.
> This is why you should use a GPIO pin for the CS line. Sending 
commands 
> is now like:
> 
>     CS = Low, S0SPCR = 0x0C6E, S0SPDR = cmd, wait for SPI transfer 
> complete, CS = high.
> 
> Data:
> 
>     CS = Low, S0SPCR = 0xE6E, SOSPDR = addr/data, wait for SPI tr. 
> compl, S0SPCR=0x86E, S0SPDR = data/data, wait, (more data), CS = 
High
> 
> You cannot use SSEL for the CS line, the SSEL line will go 
inactive 
> between datatransfers.
> 
> Think I still prefer an I2C display, SPI only makes sense if you 
have a 
> larger (graphical) display.
> 
> Good luck,
> 
>     Rob