initial commit

3rd-part/dwt_delay/LICENSE

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+MIT License
+
+Copyright (c) 2017 and so on
+
+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.

3rd-part/dwt_delay/README.md

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+# dwt_delay
+Microseconds delay lib based on DWT for STM32 or whatever ARM supporting it. 
+Just include `dwt_delay.h` in your project, call `DWT_Init()` and then use delays as needed.
+
+Depending on MCU used, you may need to include another header file (with MCU peripherals defines) in `dwt_delay.h`.
+The `stm32f1xx.h` is included by default, allowing STM32F1xx to start out of the box.
+If you don't use STM32 MCU or CubeMX, read a section at the end.  
+
+Functions are named as DWT_* to be HAL-alike. Feel free to do whatever you like with this lib,
+change names, indents, coding style, use it in LHC firmware.
+
+
+## Example
+
+```c
+/* main.c */
+
+#include "dwt_delay.h"
+
+
+void main (void)
+{
+    // Init section of your code
+    DWT_Init();
+
+
+    while(1) {
+        // Delay for 42us
+        DWT_Delay(42);
+    }
+
+}
+```
+
+## Notes on Cortex-M0/0+/1
+Unfortunately, these are not supported, since cores have no access to DWT. CMSIS library states:
+```
+Cortex-M0/0+/1 Core Debug Registers are only accessible over DAP and not via processor
+``` 
+You may want a delay function based on hardware timer instead.
+
+
+## What about Cortex-M35/55/85?
+I don't have any of these to check, but in theory they are supported.
+Anyway you have to change `CoreDebug` to `DCB`, because `CoreDebug` is deprecated in these cores.
+
+Hence, init sequence should be something like:
+```c
+DCB->DEMCR |= ‎DCB_DEMCR_TRCENA_Msk;
+``` 
+
+
+## I'm not with STM but need microsec delays
+There's an option to try! Also suits those, who use STM32, but dont use HAL/LL libs.
+
+Include a CMSIS header file according to your core in `dwt_delay.c` and change `SystemCoreClock`
+variable to whatever you probably have in the project representing clock frequency (in Hz).
+
+Something like this:
+```c
+// In dwt_delay.c
+
+#include "dwt_delay.h"
+#include "core_cm4.h"                   // CMSIS header
+
+#define SystemCoreClock   NameOfTheGlobalVariableInYourProject_or_AnotherDefine
+// or at least
+#define SystemCoreClock   48000000UL    // Clock is 48Mhz
+...
+``` 
+
+
+## Changelog
+- **2018-01-06**
+This lib emerged.
+
+- **2019-02-19**
+Overflow check added.
+
+- **2019-03-26**
+Typo in definition fixed. Got back to short and simpler function.
+
+- **2023-11-21**
+Now it is MIT License. Added warning for Cortex-M0/0+/1 and notes regarding other Cortex-M cores.

3rd-part/dwt_delay/dwt_delay.c

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+/*
+ * Simple microseconds delay routine, utilizing ARM's DWT
+ * (Data Watchpoint and Trace Unit) and HAL library.
+ * Intended to use with gcc compiler, but I hope it can be used
+ * with any other C compiler across the Universe (provided that
+ * ARM and CMSIS already invented) :)
+ * Max K
+ *
+ *
+ * This file is part of DWT_Delay package.
+ * DWT_Delay is free software: you can redistribute it and/or modify it
+ * under the terms of the MIT License
+ */
+
+// #include "stm32f1xx_hal.h"          // change to whatever MCU or Cortex-M core you use
+#include "dwt_delay.h"
+#include "at32f413.h"                   // CMSIS header
+
+/**
+ * Initialization routine.
+ * You might need to enable access to DWT registers on Cortex-M7
+ *   DWT->LAR = 0xC5ACCE55
+ */
+void DWT_Init(void)
+{
+    if (!(CoreDebug->DEMCR & CoreDebug_DEMCR_TRCENA_Msk)) {
+        CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
+        DWT->CYCCNT = 0;
+        DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
+    }
+}
+
+#if DWT_DELAY_NEWBIE
+/**
+ * If you are a newbie and see magic in DWT_Delay, consider this more
+ * illustrative function, where you explicitly determine a counter
+ * value when delay should stop while keeping things in bounds of uint32.
+ *
+ * @param uint32_t us  Number of microseconds to delay for
+*/
+void DWT_Delay(uint32_t us)
+{
+    uint32_t startTick  = DWT->CYCCNT,
+             targetTick = DWT->CYCCNT + us * (SystemCoreClock/1000000);
+
+    // Must check if target tick is out of bounds and overflowed
+    if (targetTick > startTick) {
+        // Not overflowed
+        while (DWT->CYCCNT < targetTick);
+    } else {
+        // Overflowed
+        while (DWT->CYCCNT > startTick || DWT->CYCCNT < targetTick);
+    }
+}
+#else
+/**
+ * Delay routine itself.
+ * Time is in microseconds (1/1000000th of a second), not to be
+ * confused with millisecond (1/1000th).
+ *
+ * No need to check an overflow. Let it just tick :)
+ *
+ * @param uint32_t us  Number of microseconds to delay for
+ */
+void DWT_Delay(uint32_t us)
+{
+    uint32_t startTick = DWT->CYCCNT,
+             delayTicks = us * (SystemCoreClock/1000000);
+
+    while (DWT->CYCCNT - startTick < delayTicks);
+}
+
+#endif

3rd-part/dwt_delay/dwt_delay.h

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+/*
+ * Simple microseconds delay routine, utilizing ARM's DWT
+ * (Data Watchpoint and Trace Unit) and HAL library.
+ * Intended to use with gcc compiler, but I hope it can be used
+ * with any other C compiler across the Universe (provided that
+ * ARM and CMSIS already invented) :)
+ * Max K
+ *
+ *
+ * This file is part of DWT_Delay package.
+ * DWT_Delay is free software: you can redistribute it and/or modify it
+ * under the terms of the MIT License.
+ */
+
+#if defined(__CORTEX_M) && __CORTEX_M < 3U
+#warning DWT_Delay in useless in this project since DWT unit is not accessible \
+         by processor on Cortex-M0/0+/1 cores. You may want to implement microdelays \
+         with hardware timer.
+#endif
+
+#ifndef INC_DWT_DELAY_H_
+#define INC_DWT_DELAY_H_
+
+#include <stdint.h>
+
+#define DWT_DELAY_NEWBIE 0
+
+void DWT_Init(void);
+void DWT_Delay(uint32_t us);
+
+#endif /* INC_DWT_DELAY_H_ */