| 1 | /* -*- c++ -*- */
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| 2 | /*-----------------------------------------------------------------------------
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| 3 | * Timer handling for FX2
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| 4 | *-----------------------------------------------------------------------------
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| 5 | * Code taken from USRP2 firmware (GNU Radio Project), version 3.0.2,
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| 6 | * Copyright 2003 Free Software Foundation, Inc.
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| 7 | *-----------------------------------------------------------------------------
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| 8 | * This code is part of usbjtag. usbjtag is free software; you can redistribute
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| 9 | * it and/or modify it under the terms of the GNU General Public License as
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| 10 | * published by the Free Software Foundation; either version 2 of the License,
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| 11 | * or (at your option) any later version. usbjtag is distributed in the hope
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| 12 | * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
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| 13 | * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details. You should have received a
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| 15 | * copy of the GNU General Public License along with this program in the file
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| 16 | * COPYING; if not, write to the Free Software Foundation, Inc., 51 Franklin
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| 17 | * St, Fifth Floor, Boston, MA 02110-1301 USA
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| 18 | *-----------------------------------------------------------------------------
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| 19 | */
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| 20 |
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| 21 | #include "timer.h"
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| 22 | #include "fx2regs.h"
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| 23 | #include "isr.h"
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| 24 |
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| 25 | /*
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| 26 | * Arrange to have isr_tick_handler called at 100 Hz.
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| 27 | *
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| 28 | * The cpu clock is running at 48e6. The input to the timer
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| 29 | * is 48e6 / 12 = 4e6.
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| 30 | *
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| 31 | * We arrange to have the timer overflow every 40000 clocks == 100 Hz
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| 32 | */
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| 33 |
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| 34 | #define RELOAD_VALUE ((unsigned short) -40000)
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| 35 |
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| 36 | void
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| 37 | hook_timer_tick (unsigned short isr_tick_handler)
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| 38 | {
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| 39 | ET2 = 0; // disable timer 2 interrupts
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| 40 | hook_sv (SV_TIMER_2, isr_tick_handler);
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| 41 |
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| 42 | RCAP2H = RELOAD_VALUE >> 8; // setup the auto reload value
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| 43 | RCAP2L = RELOAD_VALUE & 0xFF;
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| 44 |
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| 45 | T2CON = 0x04; // interrupt on overflow; reload; run
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| 46 | ET2 = 1; // enable timer 2 interrupts
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| 47 | }
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