///////////////////////////////////////////////////////////////////////////////
// bar_graph_skel.c
// Tests functionality of the bar_graph display 
///////////////////////////////////////////////////////////////////////////////

//PORT D connections
//   PORT D:               7  6  5  4  3  2  1  0
//              SCK (SCK)--|  |  |  |  |  |  |  |--unused         
//             MISO (MISO)----|  |  |  |  |  |-----unused
//             MOSI (MOSI)-------|  |  |  |--------unused  
//           (unused) SS_n----------|  |-----------unused
// *SS_n is unused but must be configred as an output in master mode

//PORT (E) connections
//   PORT E:         7  6  5  4  3  2  1  0
//      not present--|  |  |  |  |  |  |  |--RCLK
//      not present-----|  |  |  |  |  |-----unused
//      not present--------|     |  |--------unused
//      not present-----------|  |-----------unused

//PORT (C) connections
//   PORT C:         7  6  5  4  3  2  1  0
//      not present--|  |  |  |  |  |  |  |--OE_n (PWM dimming)
//      not present-----|  |  |  |  |  |-----unused
//      not present--------|     |  |--------unused
//      not present-----------|  |-----------unused

#include <avr/io.h>
#include <util/delay.h>

///////////////////////////////////////////////////////////////////////////////
//                      Initalize Port D SPI 
//
void init_SPID(void){
//SPI enabled, master mode, data mode0, MSB 1st, clk/4 
  PORTD.DIRSET  |= ???????; //configure SPI pins on port D    
  SPID.CTRL     |= ???????; //setup SPI   
  SPID.INTCTRL  = 0x00; //no interrupts                
  }
///////////////////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////
void init_32Mhz_RC_clk(void){
//setup 32Mhz internal RC clock
  OSC.CTRL = OSC_RC32MEN_bm; //enable 32MHz clock
  while (!(OSC.STATUS & OSC_RC32MRDY_bm)); //wait for clock to be ready
  CCP = CCP_IOREG_gc; //enable protected register change
  CLK.CTRL = CLK_SCLKSEL_RC32M_gc; //switch to 32MHz clock
}
///////////////////////////////////////////////////////////////////////////////

///////////////////////////////////////////////////////////////////////////////
//setup TC0 for single slope PWM 
void init_TC0_PWM(void){
  TCC0_CTRLA |= TC_CLKSEL_DIV8_gc; //sysclock div 8  
  TCC0_CTRLB |= TC_WGMODE_SINGLESLOPE_gc | TC0_CCAEN_bm; //single slope, pin on
  TCC0_CCA = 0xD0;    //compare level set (bigger values=dimmer)
  TCC0_PER = 0x00f0;  //period set
  PORTC.DIRSET |= PIN0_bm;  //PC.0 is the PWM output. (OC0A)
}
///////////////////////////////////////////////////////////////////////////////

int main(void){

  uint8_t spi_data_out = ??????????; //initalize output data

  init_32Mhz_RC_clk(); //set clock to 32Mhz
  init_TC0_PWM();      //single slope PWM for dimming
  init_SPID();         //setup SPI on PORT D

  PORTE.DIRSET  |= ????????????;  //RCLK pin as output   
  PORTE.OUT     &= ????????????; //RCLK pin starts logic low

  while(1){
  ????????????????????????; //send data to SPI port
  ????????????????????????; //wait for SPI completion
  ????????????????????;     //toggle RCLK high 
  ????????????????????;     //RCLK goes back low 
  ????????????????????;     //shift bits  
  ????????????????????;     //check for wrap around
  _delay_ms(250);           //make display visible
  };//while 
}//main