// 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 "ucoo/arch/reg.hh" #include "ucoo/arch/rcc.stm32.hh" #include namespace ucoo { void delay_us (int us) { // Suppose that frequency is a multiple of 8 MHz (to avoid 64 bit // division). int systick_mhz = rcc_ahb_freq_hz / (8 * 1000000); int cycles = systick_mhz * us; reg::SysTick->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); reg::SysTick->LOAD = loop_cycles - 1; reg::SysTick->VAL = 0; reg::SysTick->CTRL = SysTick_CTRL_ENABLE_Msk; while (!(reg::SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk)) ; reg::SysTick->CTRL = 0; cycles -= loop_cycles; } } void delay_ns (int ns) { // Suppose that frequency is a multiple of 1 MHz (to avoid 64 bit // division). int hclock_mhz = rcc_ahb_freq_hz / 1000000; int cycles = (hclock_mhz * ns + 999) / 1000; reg::SysTick->CTRL = 0; // Loop once, ns is supposed to be small. reg::SysTick->LOAD = cycles - 1; reg::SysTick->VAL = 0; reg::SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk; while (!(reg::SysTick->CTRL & SysTick_CTRL_COUNTFLAG_Msk)) ; reg::SysTick->CTRL = 0; } } // namespace ucoo