1 files changed, 287 insertions, 0 deletions
diff --git a/src/sim/sim.ino b/src/sim/sim.ino
new file mode 100644
index 0000000..fb12269
--- /dev/null
+++ b/src/sim/sim.ino
@@ -0,0 +1,287 @@
+/* SIM card for ATMEL
+ *
+ * (C) 2020 by Andreas Eversberg <jolly@eversberg.eu>
+ * All Rights Reserved
+ *
+ * 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, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+extern "C"
+{
+  #include "sim.h"
+  #include "eeprom.h"
+}
+
+/* settings for ATTINY85 */
+#if defined(__AVR_ATtiny85__)
+#define SERIAL_DATA  4
+#define SERIAL_DELAY 124
+#define SERIAL_TIMEOUT 1200 /* > two bytes */
+#else
+/* settings for Arduino UNO with 16 MHz */
+#define STATUS_LED   LED_BUILTIN
+#define RESET_PIN    6
+#define SERIAL_DATA  7
+#define SERIAL_DELAY 410
+#define SERIAL_TIMEOUT 2500 /* > two bytes */
+#endif
+/* to set fused for ATTINY85:
+ * avrdude -c usbasp-clone -p t85 -U lfuse:w:0xc0:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m
+ */
+
+/* timing test TX (010101010011) */
+//#define TEST_TX
+/* timing test RX (000000000001) */
+//#define TEST_RX
+/* timing test timeout (pause + 000000000001) */
+//#define TEST_TO
+
+sim_sim_t sim;
+
+#include <avr/eeprom.h>
+#include <util/delay.h>
+
+uint8_t eeprom_read(enum eeprom_locations loc)
+{
+  return eeprom_read_byte((uint8_t *)loc);
+}
+
+void eeprom_write(enum eeprom_locations loc, uint8_t value)
+{
+  eeprom_write_byte((uint8_t *)loc, value);
+}
+
+size_t eeprom_length(void)
+{
+  return 512;
+}
+
+#ifdef RESET_PIN
+volatile uint8_t *reset_in;
+uint8_t reset_bit;
+
+/* init reset pin */
+void reset_init(uint8_t pin)
+{
+  uint8_t port;
+  volatile uint8_t *mode, *out;
+
+  reset_bit = digitalPinToBitMask(pin);
+  port = digitalPinToPort(pin);
+
+  mode = portModeRegister(port);
+  out = portOutputRegister(port);
+  reset_in = portInputRegister(port);
+
+  *mode &= ~reset_bit; /* intput */
+  *out |= reset_bit; /* pullup */
+}
+#endif
+
+volatile uint8_t *serial_mode, *serial_out, *serial_in;
+uint8_t serial_bit;
+uint16_t serial_delay;
+
+/* init serial pin */
+void serial_init(uint8_t pin, uint16_t delay)
+{
+  uint8_t port;
+
+  serial_delay = delay;
+  serial_bit = digitalPinToBitMask(pin);
+  port = digitalPinToPort(pin);
+
+  serial_mode = portModeRegister(port);
+  serial_out = portOutputRegister(port);
+  serial_in = portInputRegister(port);
+
+  *serial_mode &= ~serial_bit; /* input */
+  *serial_out |= serial_bit; /* pullup */
+}
+
+/* wait some time so the stop bits haven been elapsed before transmitting a block */
+void serial_start_tx(void)
+{
+  /* wait some time, so previous stop bits have been elapsed */
+  _delay_loop_2(serial_delay * 3); /* 2..3 bits of time */
+}
+
+/* transmit a byte */
+void serial_tx(uint8_t b)
+{
+  uint8_t i, c = 0;
+
+  /* start bit */
+  *serial_mode |= serial_bit; /* output */
+  *serial_out &= ~serial_bit; /* low */
+  _delay_loop_2(serial_delay);
+  /* 8 data bits */
+  for (i = 8; i > 0; --i) {
+    if (b & 1)
+      *serial_out |= serial_bit; /* high */
+    else
+      *serial_out &= ~serial_bit; /* low */
+    _delay_loop_2(serial_delay);
+    c ^= b;
+    b>>= 1;
+  }
+  /* even parity */
+  if (c & 1)
+    *serial_out |= serial_bit; /* high */
+  else
+    *serial_out &= ~serial_bit; /* low */
+  _delay_loop_2(serial_delay);
+  /* 2 stop bits */
+  *serial_out |= serial_bit; /* high */
+  _delay_loop_2(serial_delay);
+  _delay_loop_2(serial_delay);
+  *serial_mode &= ~serial_bit; /* input */
+}
+
+/* receive a byte */
+uint8_t serial_rx(void)
+{
+  uint8_t i, b = 0;
+
+  /* center read */
+  _delay_loop_2(serial_delay >> 1);
+  /* 8 data bits */
+  for (i = 8; i > 0; --i) {
+    _delay_loop_2(serial_delay);
+    b >>= 1;
+    if ((*serial_in & serial_bit))
+      b |= 0x80;
+  }
+  /* parity */
+  _delay_loop_2(serial_delay);
+  /* move into (first) stop bit */
+  _delay_loop_2(serial_delay);
+
+  return b;
+}
+
+void setup() {
+  uint8_t byte, ver;
+
+#ifdef STATUS_LED
+  pinMode(STATUS_LED, OUTPUT);
+#endif
+
+  /* intial eeprom init */
+  byte = eeprom_read(EEPROM_MAGIC + 0);
+  ver = eeprom_read(EEPROM_MAGIC + 1);
+  if (byte != 'C' || ver != '0' + EEPROM_VERSION)
+    sim_init_eeprom();
+
+#ifdef RESET_PIN
+  reset_init(RESET_PIN);
+#endif
+  serial_init(SERIAL_DATA, SERIAL_DELAY);
+#ifdef TEST_TX
+  while (true)
+    serial_tx(0x55);
+#endif
+#ifdef TEST_RX
+  *serial_mode |= serial_bit; /* output */
+  while (true) {
+    /* show low for start bit up to end of first stop bit */
+    *serial_out &= ~serial_bit; /* low */
+    serial_rx();
+    _delay_loop_2(serial_delay >> 1);
+    *serial_out |= serial_bit; /* high */
+    _delay_loop_2(serial_delay);
+  }
+#endif
+#ifdef TEST_TO
+  uint16_t to;
+  int rx;
+  rx_again:
+  rx = 1;
+  /* wait until start bit is received or timeout */
+  for (to = 0; to <= SERIAL_TIMEOUT;) {
+    if (!(*serial_in & serial_bit)) {
+      serial_tx(0x33);
+      goto rx_again;
+    }
+#ifdef RESET_PIN
+    if (!(*reset_in & reset_bit)) {
+      serial_tx(0xf0);
+      goto rx_again;
+    }
+#endif
+    if (rx)
+      to++;
+  }
+  serial_tx(0x55);
+  goto rx_again;
+#endif
+}
+
+void loop() {
+#if !defined(TEST_TX) && !defined(TEST_RX) && !defined (TEST_TO)
+  uint16_t to;
+  int c, rx;
+
+reset_again:
+#ifdef RESET_PIN
+  /* wait until reset is released */
+  while(!(*reset_in & reset_bit));
+#endif
+  sim_reset(&sim, 0);
+
+tx_again:
+#ifdef STATUS_LED
+  digitalWrite(STATUS_LED, LOW);
+#endif
+  /* send buffer until no more data to be transmitted */
+  serial_start_tx();
+  while ((c = sim_tx(&sim)) >= 0) {
+#ifdef RESET_PIN
+    /* perform reset, when low */
+    if (!(*reset_in & reset_bit))
+      goto reset_again;
+#endif
+    /* perform transmission of a byte */
+    serial_tx(c);
+  }
+  /* wait until start bit is received or timeout */
+  rx = 0;
+  for (to = 0; to <= SERIAL_TIMEOUT;) {
+    /* perform RX, when low (start bit) */
+    if (!(*serial_in & serial_bit)) {
+      c = serial_rx();
+      /* if block was completly received, go to tx_again */
+      if (sim_rx(&sim, c) < 0)
+	      goto tx_again;
+      /* start counting timeout condition */
+      rx = 1;
+      to = 0;
+#ifdef STATUS_LED
+      digitalWrite(STATUS_LED, HIGH);
+#endif
+    }
+#ifdef RESET_PIN
+    /* perform reset, when low */
+    if (!(*reset_in & reset_bit))
+      goto reset_again;
+#endif
+    /* only if we have an ongoing reception, we count for the timeout condition */
+    if (rx)
+      to++;
+  }
+  /* perform timeout */
+  sim_timeout(&sim);
+  goto tx_again;
+#endif
+}