From 82fc54a1ceb3473e7a79a02dbc65abc556cdf93b Mon Sep 17 00:00:00 2001
From: Othmar Gsenger <otti@wirdorange.org>
Date: Tue, 5 Feb 2013 23:37:16 +0000
Subject: motor with timer working

git-svn-id: https://svn.spreadspace.org/avr/trunk@120 aa12f405-d877-488e-9caf-2d797e2a1cc7
---
 usb-i2c-sl018/stepper.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

(limited to 'usb-i2c-sl018/stepper.c')

diff --git a/usb-i2c-sl018/stepper.c b/usb-i2c-sl018/stepper.c
index 868fff0..4264a42 100644
--- a/usb-i2c-sl018/stepper.c
+++ b/usb-i2c-sl018/stepper.c
@@ -46,10 +46,18 @@ uint8_t step_table [] =
 #define STEPPER_OUTPUT_BITMASK (~(0xF << STEPPER_FIRST_BIT ))
 
 volatile uint16_t step_cnt = 0;
-static uint16_t step_cnt_max = LENGTH_STEP_TABLE*20;
+static uint16_t step_cnt_max = LENGTH_STEP_TABLE*200;
 stepper_direction_t step_direction = dir_open;
 
-void handle_step(void)
+inline void stop_stepper(void)
+{
+  // stop timer here
+  STEPPER_PORT &= ~(0xF << STEPPER_FIRST_BIT | 1<<STEPPER_ENABLE_BIT);
+  TCCR1B = 0; // no clock source
+  TIMSK1 = 0; // disable timer interrupt
+}
+
+inline uint8_t handle_step(void)
 {
   if(step_cnt < step_cnt_max)
   {
@@ -57,8 +65,10 @@ void handle_step(void)
     uint8_t stepper_output=step_table[step_cnt % LENGTH_STEP_TABLE];
     stepper_output<<=STEPPER_FIRST_BIT;
     STEPPER_PORT = (STEPPER_PORT & STEPPER_OUTPUT_BITMASK ) | stepper_output;
+    return 1;
   } else {
     stop_stepper();
+    return 0;
   }
 }
 
@@ -74,12 +84,17 @@ void start_stepper(stepper_direction_t direction)
   step_direction = direction;
   STEPPER_PORT |= 1<<STEPPER_ENABLE_BIT;
   //start timer here
+  // timer 1: 2 ms, between stepper output state changes
+  TCCR1A = 0;                    // prescaler 1:256, WGM = 4 (CTC)
+  TCCR1B = 1<<WGM12 | 1<<CS12;   //
+  OCR1A = 124;        // (1+124)*256 = 32000 -> 2 ms @ 16 MHz
+  //OCR1A = 155;        // (1+155)*256 = 40000 -> 2 ms @ 20 MHz
+  TCNT1 = 0;          // reseting timer
+  TIMSK1 = 1<<OCIE1A; // enable Interrupt
 }
 
-void stop_stepper(void)
+
+ISR(TIMER1_COMPA_vect)
 {
-  // stop timer here
-  STEPPER_PORT &= ~(0xF << STEPPER_FIRST_BIT | 1<<STEPPER_ENABLE_BIT);
+  handle_step();
 }
-
-
-- 
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