Re: [ECOS] Atmel Dataflash driver in combination with AT91SAM7SE512

["Tom Deconinck" <t dot deconinck at gmail dot com>]

On 10/23/07, Andrew Lunn <andrew@lunn.ch> wrote:
> On Tue, Oct 23, 2007 at 02:38:07PM +0200, Tom Deconinck wrote:
> > Hi,
> >
> > I'm currently working on porting eCos to support the Atmel
> > AT91SAM7SE-EK board. This board hosts the Atmel AT91SAM7SE512, which
> > is very similar to the AT91SAM7S which is already supported. The main
> > differences are the support for an EBI (external bus interface) to
> > interface all kind of memory devices and the incorporated SDRAM
> > controller.
> > I'm using the normal eCos branch enhanced with the flash_v2 branch extensions.
> >
> > I was playing around with the SPI peripheral and an Atmel AT45DB041B
> > and the dataflash driver. The AT91SAM7SE512 forces me to pick a
> > certain SPI mode, so I configured the controller to use SPI mode 0
>
> As far as i can remember, the SAM7 supports all modes and each device
> can configure its own mode. What is the reason you cannot use the mode
> the opcodes are valid for?
>
>     Andrew
>
The reason seems to be my Beagle I2C/SPI analyzer. If I disconnect it,
I can get it working with the opcodes present in the dataflash driver.
If I hook it up, it seems to screw up the data on MISO unless I hard
configure the SPI bus to either mode 0 or 3. I'm rather puzzled, but
that seems to be it...

I also had an issue with the df_read_status function: the returned
status struct got "scrambled".
I'll try to explain what I have seen.
The df_read_status function reads out the dataflash status register
and returns that byte as a casted status bitfield struct.
When I diag_printf the fields of the status struct inside
df_read_status all values are as expected. In my case the status
register reads 0x9C, giving me a device id of 0x07 in the status
struct, which corresponds with the AT45DB041B that I'm using.
But when I check the status struct that is returned by df_status_read
in df_detect_device, the device_id is 0x02 all of the sudden, causing
the dataflash init to fail.

The original df_read_status:

{
 cyg_spi_device  *spi_dev    = dev->spi_dev;
    const cyg_uint8  cmd_buf[2] = { DF_STATUS_READ_CMD, 0 };
    cyg_uint8        rx_buf[2];
    df_status_t     *p_status;
df_status_t		 status;

   cyg_spi_transaction_transfer(spi_dev, true, 2, cmd_buf, rx_buf, true);

   status = (df_status_t*) &rx_buf[1];

   return *status;

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