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authorNicolas Schodet2015-06-03 13:46:44 +0200
committerNicolas Schodet2019-10-07 00:44:44 +0200
commit574480980dcffbfa7cd6dbe71e88253eb4c9feba (patch)
tree5f1c1261341a7c2a56de01d8c6d0815b164be8ba /ucoo/utils/delay.arm.cc
parentd415a0646e874848cd06482c5d57916cca5cff4a (diff)
Rename ucoolib modules directory from ucoolib to ucoo
Diffstat (limited to 'ucoo/utils/delay.arm.cc')
-rw-r--r--ucoo/utils/delay.arm.cc76
1 files changed, 76 insertions, 0 deletions
diff --git a/ucoo/utils/delay.arm.cc b/ucoo/utils/delay.arm.cc
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+// ucoolib - Microcontroller object oriented library. {{{
+//
+// Copyright (C) 2012 Nicolas Schodet
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the "Software"),
+// to deal in the Software without restriction, including without limitation
+// the rights to use, copy, modify, merge, publish, distribute, sublicense,
+// and/or sell copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+//
+// }}}
+#include "delay.arm.hh"
+
+#include <algorithm>
+
+#include <libopencm3/cm3/systick.h>
+#include <libopencm3/stm32/f4/rcc.h>
+
+namespace ucoo {
+
+void
+delay_us (int us)
+{
+ // Horrible hack: there is no record of the current systick speed, make
+ // guesses based on APB2 clock. Also, suppose that frequency is a multiple
+ // of 1 MHz (to avoid 64 bit division).
+ int systick_mhz = rcc_ppre2_frequency / (4 * 1000000);
+ int cycles = systick_mhz * us;
+ STK_CTRL = 0;
+ // Loop several times if cycles is too big for the systick timer. Some
+ // nanoseconds are lost every second, I can live with that, it simplifies
+ // code.
+ while (cycles)
+ {
+ int loop_cycles = std::min (1 << 24, cycles);
+ STK_LOAD = loop_cycles - 1;
+ STK_VAL = 0;
+ STK_CTRL = STK_CTRL_ENABLE;
+ while (!(STK_CTRL & STK_CTRL_COUNTFLAG))
+ ;
+ STK_CTRL = 0;
+ cycles -= loop_cycles;
+ }
+}
+
+void
+delay_ns (int ns)
+{
+ // Horrible hack: there is no record of the current hclock speed, make
+ // guesses based on APB2 clock. Also, suppose that frequency is a multiple
+ // of 1 MHz (to avoid 64 bit division).
+ int hclock_mhz = rcc_ppre2_frequency / (1000000 / 2);
+ int cycles = (hclock_mhz * ns + 999) / 1000;
+ STK_CTRL = 0;
+ // Loop once, ns is supposed to be small.
+ STK_LOAD = cycles - 1;
+ STK_VAL = 0;
+ STK_CTRL = STK_CTRL_CLKSOURCE_AHB | STK_CTRL_ENABLE;
+ while (!(STK_CTRL & STK_CTRL_COUNTFLAG))
+ ;
+ STK_CTRL = 0;
+}
+
+} // namespace ucoo