Made various changes to reduce code size, including making ADC and DAC initialization optional if unused, using VARIANT_MCK instead of SystemCoreClock in init(), and converting some RMW to writes. Added config.h file for configuration. (boards.txt in later commit)

Author: mattairtech

bootloaders/zero/board_startup.c

@@ -130,12 +130,9 @@ void Reset_Handler( void )
 #if (SAMD21_SERIES || SAMD11_SERIES)
   SBMATRIX->SFR[SBMATRIX_SLAVE_HMCRAMC0].reg = 2;
 
-  USB->DEVICE.QOSCTRL.bit.CQOS = 2;
-  USB->DEVICE.QOSCTRL.bit.DQOS = 2;
+  USB->DEVICE.QOSCTRL.reg = (USB_QOSCTRL_CQOS(2) | USB_QOSCTRL_DQOS(2));
 
-  DMAC->QOSCTRL.bit.DQOS = 2;
-  DMAC->QOSCTRL.bit.FQOS = 2;
-  DMAC->QOSCTRL.bit.WRBQOS = 2;
+  DMAC->QOSCTRL.reg = (DMAC_QOSCTRL_WRBQOS(2) | DMAC_QOSCTRL_FQOS(2) | DMAC_QOSCTRL_DQOS(2));
 #endif
 
 #if (SAMD51)

config.h

@@ -0,0 +1,86 @@
+/*
+ *  Copyright (c) 2018 MattairTech LLC. All right reserved.
+ * 
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ * 
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ *  See the GNU Lesser General Public License for more details.
+ * 
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _CONFIG_H_
+#define _CONFIG_H_
+
+/* Currently, there are only two options in the menu, to enable or disable config.h.
+ * When config.h is enabled, comment out lines to disable individual options.
+ */
+#if defined(CONFIG_H_ENABLED)
+
+  /* The standard PinDescription table uses 12 bytes per pin. Define PIN_DESCRIPTION_TABLE_SIMPLE
+   * to use a more compact format that uses only 4 bytes per pin (currently only available
+   * for the D11 chips). In this case, the PinType, PinAttribute, and GCLKCCL columns are not used
+   * (they are not required). Additionally, the SetPortPin() and SetExtIntADC() macros are used to
+   * pack Port and Pin into the PortPin column, and ExtInt and ADCChannelNumber into the ExtIntADC
+   * column. See the variant README.md for more information. Note that external libraries that
+   * reference the PinDescription table directly (uncommon) will no longer work. This define can be 
+   * combined with the PIN_MAP_COMPACT define, which is available in variant.h of the D11 variants.
+   * This can save from 10's to over 250 bytes.
+   *
+   * Note that when using this define, EXTERNAL_INT_15 and the EXTERNAL_INT_NMI are NOT available
+   * and only ADC_Channel0 through ADC_Channel14 are available.
+   */
+  //#define PIN_DESCRIPTION_TABLE_SIMPLE
+
+  /* Define PIN_PERIPHERAL_CHECKS_DISABLED to disable some sanity and other checks at the beginning 
+   * of pinPeripheral() (ie: out of bounds access, pin isn't usable as PIO, verify hardware peripheral
+   * requested actually exists on pin). This saves about 100 bytes.
+   */
+  #define PIN_PERIPHERAL_CHECKS_DISABLED
+
+  /* Define ADC_NO_INIT_IF_UNUSED and/or REF_NO_INIT_IF_UNUSED to save the code space used by the
+   * initialization functions of the ADC, DAC, and REF, if they are not used by the core. Do not
+   * set this define if an external library is used for the ADC, DAC, or REF, as that library probably
+   * expects the associated hardware to be already initialized. Note that if using a core function
+   * (ie: analogWrite()), initialization will still occur automatically. This saves about 350 bytes
+   * with ADC_NO_INIT_IF_UNUSED and 50 bytes with DAC_NO_INIT_IF_UNUSED.
+   */
+  #define ADC_NO_INIT_IF_UNUSED
+  #define DAC_NO_INIT_IF_UNUSED
+
+  /* Define DISABLE_ADC_CALIBRATION to disable ADC calibration using the NVM factory values, which
+   * occurs during initialization, and save a few bytes. This setting is not generally recommended.
+   */
+  //#define DISABLE_ADC_CALIBRATION
+
+  /* Define TRUST_RESET_DEFAULTS to avoid writing default values into registers during hardware
+   * initialization, saving about 50 bytes (currently).
+   */
+  #define TRUST_RESET_DEFAULTS
+
+  /* Define NO_ADDITIONAL_GCLKS to disable initialization of GENERIC_CLOCK_GENERATOR_192MHz (D51) and
+   * GENERIC_CLOCK_GENERATOR_48MHz (all others), which are currently unused in the core. This currently
+   * saves about 48 bytes.
+   */
+  #define NO_ADDITIONAL_GCLKS
+
+  /* Define NO_OSC_HS_GCLK to disable initialization of GENERIC_CLOCK_GENERATOR_OSC_HS, which is setup
+   * to run at 8MHz with the D21, D11, and L21, but is unused by the core. This saves about 30 bytes.
+   */
+  #define NO_OSC_HS_GCLK
+
+  /* Define NO_DELAY_HIGH_WORD to disable the high word variable (_ulTickCountHighWord) in delay.c,
+   * which is used to allow counting beyond the 50-day maximum (for a 32-bit variable counting in
+   * milliseconds). This saves about 64 bytes.
+   */
+  #define NO_DELAY_HIGH_WORD
+#endif
+
+#endif // _CONFIG_H_

cores/arduino/cortex_handlers.c

@@ -530,12 +530,9 @@ void Reset_Handler(void)
 #if (SAMD21 || SAMD11)
   SBMATRIX->SFR[SBMATRIX_SLAVE_HMCRAMC0].reg = 2;
 
-  USB->DEVICE.QOSCTRL.bit.CQOS = 2;
-  USB->DEVICE.QOSCTRL.bit.DQOS = 2;
+  USB->DEVICE.QOSCTRL.reg = (USB_QOSCTRL_CQOS(2) | USB_QOSCTRL_DQOS(2));
 
-  DMAC->QOSCTRL.bit.DQOS = 2;
-  DMAC->QOSCTRL.bit.FQOS = 2;
-  DMAC->QOSCTRL.bit.WRBQOS = 2;
+  DMAC->QOSCTRL.reg = (DMAC_QOSCTRL_WRBQOS(2) | DMAC_QOSCTRL_FQOS(2) | DMAC_QOSCTRL_DQOS(2));
 #endif
 
 #if (SAMD51)

cores/arduino/delay.c

@@ -18,14 +18,17 @@
 
 #include "delay.h"
 #include "Arduino.h"
+#include "../../config.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 /** Tick Counter united by ms */
 static volatile uint32_t _ulTickCount=0 ;
+#if !defined(NO_DELAY_HIGH_WORD)
 static volatile uint32_t _ulTickCountHighWord=0 ;
+#endif
 
 unsigned long millis( void )
 {
@@ -66,10 +69,13 @@ void delay( unsigned long ms )
 {
   if (ms)
   {
+#if !defined(NO_DELAY_HIGH_WORD)
     uint8_t enableInterrupts = ((__get_PRIMASK() & 0x1) == 0);
     __disable_irq();
+#endif
 
     uint32_t start = _ulTickCount ;
+#if !defined(NO_DELAY_HIGH_WORD)
     uint32_t targetTickCountHighWord = _ulTickCountHighWord;
 
     if (enableInterrupts) {
@@ -83,11 +89,16 @@ void delay( unsigned long ms )
       start = 0;
       targetTickCountHighWord++;
     }
+#endif
 
     do
     {
       yield() ;
+#if !defined(NO_DELAY_HIGH_WORD)
     } while (_ulTickCountHighWord < targetTickCountHighWord || (_ulTickCount - start) < ms ) ;
+#else
+    } while (_ulTickCount - start < ms ) ;
+#endif
   }
 }
 
@@ -98,10 +109,12 @@ void SysTick_DefaultHandler(void)
   // Increment tick count each ms
   _ulTickCount++;
 
+#if !defined(NO_DELAY_HIGH_WORD)
   if ( _ulTickCount == 0 )
   {
     _ulTickCountHighWord++;
   }
+#endif
 #if defined(CDC_ONLY) || defined(CDC_HID) || defined(WITH_CDC)
   tickReset();
 #endif