1 files changed, 92 insertions, 0 deletions
diff --git a/tube-rotator/stepper.c b/tube-rotator/stepper.c
new file mode 100644
index 0000000..1bb9cae
--- /dev/null
+++ b/tube-rotator/stepper.c
@@ -0,0 +1,92 @@
+/*
+ *  spreadspace avr utils
+ *
+ *
+ *  Copyright (C) 2014 Christian Pointner <equinox@spreadspace.org>
+ *
+ *  This file is part of spreadspace avr utils.
+ *
+ *  spreadspace avr utils 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
+ *  any later version.
+ *
+ *  spreadspace avr utils 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 spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <avr/sfr_defs.h>
+#include <avr/interrupt.h>
+
+#include "stepper.h"
+
+uint8_t step_table [] =
+{
+    /* full steps */
+  /* 6,  // 0110 */
+  /* 5,  // 0101 */
+  /* 9,  // 1001 */
+  /* 10, // 1010 */
+
+    /* half steps */
+  2,  // 0010
+  6,  // 0110
+  4,  // 0100
+  5,  // 0101
+  1,  // 0001
+  9,  // 1001
+  8,  // 1000
+  10, // 1010
+};
+
+#define STEPPER_PORT PORTF
+#define STEPPER_DDR DDRF
+#define STEPPER_FIRST_BIT 4
+#define STEPPER_ENABLE_A_BIT 0
+#define STEPPER_ENABLE_B_BIT 1
+#define LENGTH_STEP_TABLE (sizeof(step_table)/sizeof(uint8_t))
+#define STEPPER_OUTPUT_BITMASK (~(0xF << STEPPER_FIRST_BIT ))
+
+void stepper_init(void)
+{
+  STEPPER_PORT &= ~(0xF << STEPPER_FIRST_BIT | 1<<STEPPER_ENABLE_A_BIT | 1<<STEPPER_ENABLE_B_BIT);
+  STEPPER_DDR |= (0xF << STEPPER_FIRST_BIT) | (1<<STEPPER_ENABLE_A_BIT) | (1<<STEPPER_ENABLE_B_BIT);
+}
+
+void stepper_start(void)
+{
+  STEPPER_PORT |= (1<<STEPPER_ENABLE_A_BIT) | (1<<STEPPER_ENABLE_B_BIT);
+  TCCR1A = 0;                    // prescaler 1:256, WGM = 4 (CTC)
+  TCCR1B = 1<<WGM12 | 1<<CS12;   //
+  OCR1A = 150;
+  TCNT1 = 0;
+  TIMSK1 = 1<<OCIE1A;
+}
+
+void stepper_stop(void)
+{
+  STEPPER_PORT &= ~(0xF << STEPPER_FIRST_BIT | 1<<STEPPER_ENABLE_A_BIT | 1<<STEPPER_ENABLE_B_BIT);
+  TCCR1B = 0; // no clock source
+  TIMSK1 = 0; // disable timer interrupt
+}
+
+static inline void stepper_handle(void)
+{
+  static uint8_t step_idx = 0;
+
+  uint8_t stepper_output = step_table[step_idx];
+  stepper_output <<= STEPPER_FIRST_BIT;
+  STEPPER_PORT = (STEPPER_PORT & STEPPER_OUTPUT_BITMASK ) | stepper_output;
+  step_idx++;
+  step_idx %= LENGTH_STEP_TABLE;
+}
+
+ISR(TIMER1_COMPA_vect)
+{
+  stepper_handle();
+}