drv_spi.c

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/*
    (c) 2022 Microchip Technology Inc. and its subsidiaries. You may use this
    software and any derivatives exclusively with Microchip products.
 
    THIS SOFTWARE IS SUPPLIED BY MICROCHIP "AS IS". NO WARRANTIES, WHETHER
    EXPRESS, IMPLIED OR STATUTORY, APPLY TO THIS SOFTWARE, INCLUDING ANY IMPLIED
    WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY, AND FITNESS FOR A
    PARTICULAR PURPOSE, OR ITS INTERACTION WITH MICROCHIP PRODUCTS, COMBINATION
    WITH ANY OTHER PRODUCTS, OR USE IN ANY APPLICATION.
 
    IN NO EVENT WILL MICROCHIP BE LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE,
    INCIDENTAL OR CONSEQUENTIAL LOSS, DAMAGE, COST OR EXPENSE OF ANY KIND
    WHATSOEVER RELATED TO THE SOFTWARE, HOWEVER CAUSED, EVEN IF MICROCHIP HAS
    BEEN ADVISED OF THE POSSIBILITY OR THE DAMAGES ARE FORESEEABLE. TO THE
    FULLEST EXTENT ALLOWED BY LAW, MICROCHIP'S TOTAL LIABILITY ON ALL CLAIMS IN
    ANY WAY RELATED TO THIS SOFTWARE WILL NOT EXCEED THE AMOUNT OF FEES, IF ANY,
    THAT YOU HAVE PAID DIRECTLY TO MICROCHIP FOR THIS SOFTWARE.
 
    MICROCHIP PROVIDES THIS SOFTWARE CONDITIONALLY UPON YOUR ACCEPTANCE OF THESE
    TERMS.
 */
 
#include <p33CH512MP506.h>
#include <libpic30.h>
 
#include "drv_spi.h"
#include "driver/can/drv_can.h"
 
// MCC header files
#include "system/pins.h"
#include "spi_client/spi1.h"
#include "dma/dma.h"
#include "timer/timer_interface.h"
#include "timer/sccp1.h"
#include "timer/sccp2.h"
 
#include "system/pins.h"
 
//------------------------------------------------------------------------------
// local typedefs
//------------------------------------------------------------------------------
typedef struct
{
  bool      connected;
  uint16_t  data[4];
  bool      checksum_ok;
  int16_t   timeout_counter;
} DRV_SPI_t;
 
 
//------------------------------------------------------------------------------
// local variable definitions
//------------------------------------------------------------------------------
static DRV_SPI_t selfSpi __attribute__((address(0x1800))); // set fixed address for DMA
 
//------------------------------------------------------------------------------
// local function declarations
//------------------------------------------------------------------------------
static void SPI_Synchronize(void); // local
 
//------------------------------------------------------------------------------
// API function definitions
//------------------------------------------------------------------------------
 
 
void Drv_SPI_Reset_Timeout_Counter(uint16_t count)
{
  selfSpi.timeout_counter = count; 
}
 
 
bool Drv_SPI_get_Connected_Flag(void)
{
  return (selfSpi.connected);
}
 
 
bool Drv_SPI_get_ChecksumOK_Flag(void) // API
{
  return (selfSpi.checksum_ok);
}
 
 
uint16_t* Drv_SPI_get_Adr_Data_Obj(void)
{
  return (selfSpi.data);
}
 
 
void Drv_SPI_Timeout(void) // API
{
  selfSpi.timeout_counter--;
  if (selfSpi.timeout_counter <= 0)
  {
    // this will only get executed if there
    // has been no SPI comms for 1ms
    selfSpi.timeout_counter = 10; // 1ms (10*100us)            
    selfSpi.connected = false; // SPI not connected
    selfSpi.checksum_ok = false; // checksum invalid
    SPI_Synchronize(); // try to sync to SPI bus 
  }
}
 
 
bool Drv_SPI_Checksum(void) 
{
  bool test_passed = false;
 
  // checksum preset with 0x0055 so that transmission of all zeros won't 
  // result in a false pass
  uint16_t i;
  uint16_t checksum = 0x0055;
  for (i = 0; i < 3; i++)
  {
    checksum = checksum + selfSpi.data[i];
  }
 
  // compare calculated checksum against checksum transmitted in word 3
  if (checksum == selfSpi.data[3])
  {
    // calculated and transmitted checksums match
    selfSpi.checksum_ok = true;
    test_passed = true;
  }
  else
  {
    // calculated and transmitted checksums don't match
    selfSpi.checksum_ok = false;
    selfSpi.connected = false;
    
    // reset timeout counter so as we attempt to re-sync to SPI bus 
    // as soon as possible
    // setting 1 means that the next time Drv_SPI_Timeout() is called
    // we will attempt to re-sync to SPI bus, this should be max 100us
    selfSpi.timeout_counter = 1;  
    test_passed = false;
  }
  return (test_passed);
}
 
 
static void SPI_Synchronize(void) // local
{
  DMA_ChannelDisable(0); // disable DMA channel 0
  SPI1CON1Lbits.SPIEN = 0; // disable SPI
  
  SPI_Timeout_40us_Timer_Start();
  
//  SCCP2_TMR_Start(); // set to time out after 40us
  IFS1bits.CCT2IF = 0; // clear SCCP2 timer overflow flag
 
  // clear timer (should use MCC API functions but they don't work)
  CCP2TMRL = 0;
  CCP2TMRH = 0;
  
  SPI_BusIdle_1us_Timer_Start();
 
//  SCCP1_TMR_Start(); // set to time out after 1us
  IFS0bits.CCT1IF = 0; // clear timer overflow flag
 
  // clear timer (should use MCC API functions but they don't work)
  CCP1TMRL = 0;
  CCP1TMRH = 0;
 
  do
  {
    // stay here until one of the 2 timers expires
//    if (SCK1IN_GetValue() == 0) 
    if (_RC8 == 0)
    {
      // SPI_CLK is low, so SPI bus is not in idle state. Reset 1us timer
      CCP1TMRL = 0;
      CCP1TMRH = 0;
    }
  } while ((!IFS0bits.CCT1IF) && (!IFS1bits.CCT2IF));
 
  // check which timer expired first
  if (IFS0bits.CCT1IF)
  {
    // SCCP1 expired, meaning we detected that the SPI bus is idle
    // (SPI_CLK has been high continuously for 1us)
    // since SPI bus is idle, we can now enable the SPI and DMA peripherals
    selfSpi.connected = true;
    SPI1_Initialize();
    SPI1CON1Lbits.SPIEN = 1;
 
    DMA_Initialize();
 
    // address to which the DMA sends the incoming data (destination address)
    // is overwritten via DMADST0 register
    DMADST0 = (uint16_t) & selfSpi.data[0];
    DMA_ChannelEnable(0);
  }
  else
  {
    // SCCP2 expired, meaning we didn't detect SPI bus in idle over a 40us period 
    selfSpi.connected = false; // could not establish SPI connection, try again later
  }
 
  // stop timers and exit
  Nop();
  Nop();
  Nop();
  Nop();
  Nop();
  SPI_BusIdle_1us_Timer_Stop();
  SPI_Timeout_40us_Timer_Stop();
}