[En-Nut-Discussion] Failed to mount sdcard using at91sam7x-ek.conf, fails to write to SPI

[Adeel Ahmed Nafis]

Hi,
running into problems again. Have downloaded and built the 
ethernut-5.1.0 on linux, and have been able to program it. Tested out 
the sample app 'httpd' in app/httpd, using PHAT.
It hangs on MmCardReset() in nut/dev/mmcard.c line 1206

     for (i = 0; i < 10; i++) {

         (*ifc->mmcifc_io) (0xFF);	//hangs in this routine

     }


ifc->mmcifc_io points to  At91SpiMmCard0Io() in 
nut/arch/arm/dev/atmel/spimmc_at91.c

After writing it seems that SPI_RDRF is not set

outr(MMC_SPI_TDR, val);

/* Wait for receiver data register full. */

while((inr(MMC_SPI_SR) & SPI_RDRF) == 0);  //hangs on this line, never returns


Did not get time to scope it yet.

While trying out different things, I came across this in 
At91SpiMmcIfcInit() nut/arch/arm/dev/atmel/spimmc_at91.c

/* Set SPI to master mode, fixed peripheral at CS1, fault detection disabled. */

outr(MMC_SPI_MR, (1 << SPI_PCS_LSB) | SPI_MODFDIS | SPI_MSTR);


As we are using CS0 should not this be the following? Or does it not matter.

outr(MMC_SPI_MR, (0x0E << SPI_PCS_LSB) | SPI_MODFDIS | SPI_MSTR);


 From the datasheet pp:269

PCS: Peripheral Chip Select

This field is only used if Fixed Peripheral Select is active (PS = 0).

If PCSDEC = 0:

PCS = xxx0 NPCS[3:0] = 1110

PCS = xx01 NPCS[3:0] = 1101

PCS = x011 NPCS[3:0] = 1011

PCS = 0111 NPCS[3:0] = 0111

PCS = 1111 forbidden (no peripheral is selected)


In our case PS = 0 and PCSDEC = 0.
Any case, both PCS=1, and PCS=0x0E have no effect, on the outcome.

-- 
Adeel Nafis
Design Engineer

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