SPI problems with Due on 1.5.3

[noblepepper]

Ethernet example sketches compile but do not work on a Due. This appears to originate in the SPI library begin function in libraries/SPI/arch/sam/SPI.cpp when it is called with an argument

The begin function works properly when called with no argument as in libraries/SD/src/utility/Sd2Card.cpp but this code from libraries/Ethernet/arch/sam/utility/w5100.cpp never returns from writeMR.

SPI.begin(SPI_CS);
  // Set clock to 4Mhz (W5100 should support up to about 14Mhz)
  SPI.setClockDivider(SPI_CS, 21);
  SPI.setDataMode(SPI_CS, SPI_MODE0);

  writeMR(1<<RST);

Adding three lines to the begin function in libraries/SPI/arch/sam/SPI.cpp corrects this behaviour

void SPIClass::begin(uint8_t _pin) {
    uint32_t spiPin = BOARD_PIN_TO_SPI_PIN(_pin);

    initCb();//1
    SPI_Configure(spi, id, SPI_MR_MSTR | SPI_MR_PS | SPI_MR_MODFDIS);//2
    SPI_Enable(spi);//3
    PIO_Configure(
        g_APinDescription[spiPin].pPort,
        g_APinDescription[spiPin].ulPinType,
        g_APinDescription[spiPin].ulPin,
        g_APinDescription[spiPin].ulPinConfiguration);

    // Default speed set to 4Mhz
    setClockDivider(_pin, 21);
    setDataMode(_pin, SPI_MODE0);
    setBitOrder(_pin, MSBFIRST);
}

This still exists in the nightly build as of 9/1/2013.

[cmaglie]

Thanks for the bug report, it will be reviewed soon.
C

[cmaglie]

Fixed, your patch is correct.
Thank you very much!

2ebd47a