Subversion Repositories neorv32

// #################################################################################################
// # << NEORV32: neorv32_spi.c - Serial Peripheral Interface Controller (SPI) HW Driver >>         #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
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// # Copyright (c) 2021, Stephan Nolting. All rights reserved.                                     #
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// # The NEORV32 Processor - https://github.com/stnolting/neorv32              (c) Stephan Nolting #
// #################################################################################################
 
 
/**********************************************************************//**
 * @file neorv32_spi.c
 * @author Stephan Nolting
 * @brief Serial peripheral interface controller (SPI) HW driver source file.
 *
 * @note These functions should only be used if the SPI unit was synthesized (IO_SPI_EN = true).
 **************************************************************************/
 
#include "neorv32.h"
#include "neorv32_spi.h"
 
 
/**********************************************************************//**
 * Check if SPI unit was synthesized.
 *
 * @return 0 if SPI was not synthesized, 1 if SPI is available.
 **************************************************************************/
int neorv32_spi_available(void) {
 
  if (SYSINFO_FEATURES & (1 << SYSINFO_FEATURES_IO_SPI)) {
    return 1;
  }
  else {
    return 0;
  }
}
 
 
/**********************************************************************//**
 * Enable and configure SPI controller. The SPI control register bits are listed in #NEORV32_SPI_CT_enum.
 *
 * @param[in] prsc Clock prescaler select (0..7).  See #NEORV32_CLOCK_PRSC_enum.
 * @param[in] clk_polarity Idle clock polarity (0, 1).
 * @param[in] data_size Data transfer size (0: 8-bit, 1: 16-bit, 2: 24-bit, 3: 32-bit).
 * @param[in] irq_en Enable transfer-done interrupt when 1.
 **************************************************************************/
void neorv32_spi_setup(uint8_t prsc, uint8_t clk_polarity, uint8_t data_size, uint8_t irq_en) {
 
  SPI_CT = 0; // reset
 
  uint32_t ct_enable = 1;
  ct_enable = ct_enable << SPI_CT_EN;
 
  uint32_t ct_prsc = (uint32_t)(prsc & 0x07);
  ct_prsc = ct_prsc << SPI_CT_PRSC0;
 
  uint32_t ct_polarity = (uint32_t)(clk_polarity & 0x01);
  ct_polarity = ct_polarity << SPI_CT_CPHA;
 
  uint32_t ct_size = (uint32_t)(data_size & 0x03);
  ct_size = ct_size << SPI_CT_SIZE0;
 
  uint32_t ct_irq = (uint32_t)(irq_en & 0x01);
  ct_irq = ct_irq << SPI_CT_IRQ_EN;
 
  SPI_CT = ct_enable | ct_prsc | ct_polarity | ct_size | ct_irq;
}
 
 
/**********************************************************************//**
 * Disable and SPI controller.
 **************************************************************************/
void neorv32_spi_disable(void) {
 
  SPI_CT &= ~((uint32_t)(1 << SPI_CT_EN));
}
 
 
/**********************************************************************//**
 * Activate SPI chip select signal.
 *
 * @note The chip select output lines are LOW when activated.
 *
 * @param cs Chip select line to activate (0..7).
 **************************************************************************/
void neorv32_spi_cs_en(uint8_t cs) {
 
  uint32_t cs_mask = (uint32_t)(1 << (cs & 0x07));
  cs_mask = cs_mask << SPI_CT_CS0;
  SPI_CT |= cs_mask;
}
 
 
/**********************************************************************//**
 * Deactivate SPI chip select signal.
 *
 * @note The chip select output lines are HIGH when deactivated.
 *
 * @param cs Chip select line to deactivate (0..7).
 **************************************************************************/
void neorv32_spi_cs_dis(uint8_t cs) {
 
  uint32_t cs_mask = (uint32_t)(1 << (cs & 0x07));
  cs_mask = cs_mask << SPI_CT_CS0;
  SPI_CT &= ~cs_mask;
}
 
 
/**********************************************************************//**
 * Initiate SPI transfer.
 *
 * @warning The SPI always sends MSB first.
 *
 * @note This function is blocking.
 *
 * @param tx_data Transmit data (8/16/24/32-bit, LSB-aligned).
 * @return Receive data (8/16/24/32-bit, LSB-aligned).
 **************************************************************************/
uint32_t neorv32_spi_trans(uint32_t tx_data) {
 
  SPI_DATA = tx_data; // trigger transfer
  while((SPI_CT & (1<<SPI_CT_BUSY)) != 0); // wait for current transfer to finish
 
  return SPI_DATA;
}
 
 
/**********************************************************************//**
 * Check if SPI transceiver is busy.
 *
 * @note This function is blocking.
 *
 * @return 0 if idle, 1 if busy
 **************************************************************************/
int neorv32_spi_busy(void) {
 
  if ((SPI_CT & (1<<SPI_CT_BUSY)) != 0) {
    return 1;
  }
  return 0;
}