Subversion Repositories neo430

// #################################################################################################
// #  < neo430_spi.c - Internal SPI module driver functions >                                      #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
// #                                                                                               #
// # Copyright (c) 2020, Stephan Nolting. All rights reserved.                                     #
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// # permitted provided that the following conditions are met:                                     #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of        #
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// #    endorse or promote products derived from this software without specific prior written      #
// #    permission.                                                                                #
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// # ********************************************************************************************* #
// # The NEO430 Processor - https://github.com/stnolting/neo430                                    #
// #################################################################################################
 
#include "neo430.h"
#include "neo430_spi.h"
 
 
/* ------------------------------------------------------------
 * INFO Reset, configure speed and enable SPI module
 * INFO SPI SCK speed: f_main/(2*PRSC), prsc = see below (control reg)
 * SPI clock prescaler select:
 *  0: CLK/2
 *  1: CLK/4
 *  2: CLK/8
 *  3: CLK/64
 *  4: CLK/128
 *  5: CLK/1024
 *  6: CLK/2048
 *  7: CLK/4096
 * ------------------------------------------------------------ */
void neo430_spi_enable(uint8_t prsc) {
 
  SPI_CT = 0; // reset
  SPI_CT = (1 << SPI_CT_EN) | (prsc<<SPI_CT_PRSC0);
}
 
 
/* ------------------------------------------------------------
 * INFO Enable SPI module
 * ------------------------------------------------------------ */
void neo430_spi_disable(void) {
 
  SPI_CT = 0;
}
 
 
/* ------------------------------------------------------------
 * INFO Enable SPI CSx (set low)
 * PARAM CS line (0..5)
 * ------------------------------------------------------------ */
void neo430_spi_cs_en(uint8_t cs) {
 
  SPI_CT |= 1 << (cs+SPI_CT_CS_SEL0);
}
 
 
/* ------------------------------------------------------------
 * INFO Disable ALL SPI CS lines (set high)
 * ------------------------------------------------------------ */
void neo430_spi_cs_dis(void) {
 
  SPI_CT &= ~(0b111111 << SPI_CT_CS_SEL0); // clear all 6 CS lines
}
 
 
/* ------------------------------------------------------------
 * INFO SPI RTX byte transfer
 * PARAM d byte to be send
 * RETURN received byte
 * ------------------------------------------------------------ */
uint16_t neo430_spi_trans(uint16_t d) {
 
  SPI_RTX = d; // trigger transfer
  while((SPI_CT & (1<<SPI_CT_BUSY)) != 0); // wait for current transfer to finish
 
  return SPI_RTX;
}