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Incorrect SPI default pins for Arduino Zero #974

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@vlacorre

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@vlacorre

Hello,

Here the list of default pins for SPI for Arduino Zero seems to be misaligned with its default variant.h, variant.cpp and SPI.cpp.

The default SPI is:

  SPIClassSAMD SPI (&PERIPH_SPI,  PIN_SPI_MISO,  PIN_SPI_SCK,  PIN_SPI_MOSI,  PAD_SPI_TX,  PAD_SPI_RX);

with

#define PIN_SPI_MISO         (22u)
#define PIN_SPI_MOSI         (23u)
#define PIN_SPI_SCK          (24u)
#define PERIPH_SPI           sercom4
#define PAD_SPI_TX           SPI_PAD_2_SCK_3
#define PAD_SPI_RX           SERCOM_RX_PAD_0

which are, by default:

const PinDescription g_APinDescription[]=
{

  /**...**/

  // 22..24 - SPI pins (ICSP:MISO,SCK,MOSI)
  // ----------------------
  { PORTA, 12, PIO_SERCOM_ALT, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_12 }, // MISO: SERCOM4/PAD[0]
  { PORTB, 10, PIO_SERCOM_ALT, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_10 }, // MOSI: SERCOM4/PAD[2]
  { PORTB, 11, PIO_SERCOM_ALT, PIN_ATTR_DIGITAL, No_ADC_Channel, NOT_ON_PWM, NOT_ON_TIMER, EXTERNAL_INT_11 }, // SCK: SERCOM4/PAD[3]

  /**...**/
}

As a result, the default pins should be the ones on the ICSP header:
22 (MISO)
23 (MOSI)
24 (SCK)
and no default Chip Select (CS) pin.

Please correct me if I'm wrong. Maybe other boards are also misaligned, could be something to check.

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