-------------------------------------------------------------------------------
SPI / Atmel ATMEGA32
-------------------------------------------------------------------------------

This is a set of SPI captures from an Atmel ATMEGA32 device. The main loop of
the C program outputs an 8-bit value which is increased by one between
subsequent transmissions:

  unsigned char c = 0;
  for (;;) {
  	_delay_us(250);
  	cbi(PORTB, DD_SS);
  	SPDR = c;
  	c++;
  	while (!(SPSR & (1 << SPIF)));
  	sbi(PORTB, DD_SS);
  }


Logic analyzer setup
--------------------

The logic analyzer used was a Saleae Logic (at 500kHz).

  Probe     ATMEGA32 pins (PDIP-40)
  ---------------------------------
  0 (CS)    SS/PB4 (Pin 5)
  1 (MOSI)  MOSI/PB5 (Pin 6)
  2 (SCK)   SCK/PB7 (Pin 8)


Probing
-------

The sigrok command line used was:

  sigrok-cli --driver fx2lafw --samples=1m --config samplerate=500k -o <file>


SPI setup
---------

There are 4 different SPI setups each captured in a separate capture file
(see the ATMEGA datasheet for the meaning of the CPOL & CPHA flags).


spi_atmega32_00.sr
------------------

SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0)|(1<<SPR1);


spi_atmega32_11.sr
------------------

SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0)|(1<<SPR1) | (1<<CPOL) | (1<<CPHA);


spi_atmega32_01.sr
------------------

SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0)|(1<<SPR1) | (1<<CPHA);


spi_atmega32_10.sr
------------------

SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0)|(1<<SPR1) | (1<<CPOL);