archive MK1 AVR source

2010-09-06 23:51:48 +02:00
parent a6d66e7a8b
commit a9b84c3e0b
54 changed files with 1220 additions and 793 deletions
--- a/mk1-src/spi.c
+++ b/mk1-src/spi.c
@@ -0,0 +1,136 @@
+/* sd2snes - SD card based universal cartridge for the SNES
+   Copyright (C) 2009-2010 Maximilian Rehkopf <otakon@gmx.net>
+   This file was adapted from sd2iec, written by Ingo Korb.
+   Original copyright header follows:
+*/
+/* sd2iec - SD/MMC to Commodore serial bus interface/controller
+   Copyright (C) 2007-2009  Ingo Korb <ingo@akana.de>
+
+   Inspiration and low-level SD/MMC access based on code from MMC2IEC
+     by Lars Pontoppidan et al., see sdcard.c|h and config.h.
+
+   FAT filesystem access based on code from ChaN and Jim Brain, see ff.c|h.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License only.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+
+   spi.c: Low level SPI access
+
+   Extended, optimized and cleaned version of code from MMC2IEC,
+   original copyright header follows:
+
+//
+// Title        : SPI module
+// Author       : Lars Pontoppidan
+// Date         : January, 2007
+// Version      : 1.03
+// Target MCU   : Atmel AVR Series
+//
+// DESCRIPTION:
+// This module implements initialization, sending and receiving bytes using
+// hardware SPI on an AVR.
+//
+// DISCLAIMER:
+// The author is in no way responsible for any problems or damage caused by
+// using this code. Use at your own risk.
+//
+// LICENSE:
+// This code is distributed under the GNU Public License
+// which can be found at http://www.gnu.org/licenses/gpl.txt
+//
+
+*/
+
+// FIXME: Integrate into sdcard.c
+
+#include <avr/io.h>
+#include "avrcompat.h"
+#include "spi.h"
+
+// access routines
+void spiInit(void)
+{
+  volatile uint8_t dummy;
+
+  // setup SPI I/O pins
+  SPI_PORT = (SPI_PORT & ~SPI_MASK) | SPI_SCK | SPI_SS | SPI_MISO;
+  SPI_DDR  = (SPI_DDR  & ~SPI_MASK) | SPI_SCK | SPI_SS | SPI_MOSI;
+
+  // setup SPI interface:
+  //   interrupts disabled, SPI enabled, MSB first, master mode,
+  //   leading edge rising, sample on leading edge, clock = f/4
+  SPCR = 0b01010000;
+
+  // Enable SPI double speed mode -> clock = f/2
+  SPSR = _BV(SPI2X);
+
+  // clear status
+  dummy = SPSR;
+
+  // clear receive buffer
+  dummy = SPDR;
+}
+
+
+inline uint8_t spiTransferByte(uint8_t data)
+{
+  // send the given data
+  SPDR = data;
+
+  // wait for transfer to complete
+  loop_until_bit_is_set(SPSR, SPIF);
+  // *** reading of the SPSR and SPDR are crucial
+  // *** to the clearing of the SPIF flag
+  // *** in non-interrupt mode
+
+  // return the received data
+  return SPDR;
+}
+
+
+inline uint32_t spiTransferLong(const uint32_t data)
+{
+  // It seems to be necessary to use the union in order to get efficient
+  // assembler code.
+  // Beware, endian unsafe union
+  union {
+    uint32_t l;
+    uint8_t  c[4];
+  } long2char;
+
+  long2char.l = data;
+
+  // send the given data
+  SPDR = long2char.c[3];
+  // wait for transfer to complete
+  loop_until_bit_is_set(SPSR, SPIF);
+  long2char.c[3] = SPDR;
+
+  SPDR = long2char.c[2];
+  // wait for transfer to complete
+  loop_until_bit_is_set(SPSR, SPIF);
+  long2char.c[2] = SPDR;
+
+  SPDR = long2char.c[1];
+  // wait for transfer to complete
+  loop_until_bit_is_set(SPSR, SPIF);
+  long2char.c[1] = SPDR;
+
+  SPDR = long2char.c[0];
+  // wait for transfer to complete
+  loop_until_bit_is_set(SPSR, SPIF);
+  long2char.c[0] = SPDR;
+
+  return long2char.l;
+}