CMSIS-SVD: CMSIS-SVD Schema File Ver. 1.1 (draft)

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CMSIS-SVD Schema File Ver. 1.1 (draft)

    <?xml version="1.0" encoding="UTF-8"?>
    <!--
      date: 04.07.2012

      Copyright (C) 2011 - 2012 ARM Limited. All rights reserved.

      Redistribution and use in source and binary forms, with or without
      modification, are permitted provided that the following conditions are met:
       - Redistributions of source code must retain the above copyright
         notice, this list of conditions and the following disclaimer.
       - Redistributions in binary form must reproduce the above copyright
         notice, this list of conditions and the following disclaimer in the
         documentation and/or other materials provided with the distribution.
       - Neither the name of ARM nor the names of its contributors may be used
         to endorse or promote products derived from this software without
         specific prior written permission.

      THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
      AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS AND CONTRIBUTORS BE
      LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
      CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
      SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
      INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
      CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      POSSIBILITY OF SUCH DAMAGE.

      This is CMSIS-SVD version 1.1
      For backward compatibility all additional tags have been made optional.
      Extensions may be mandatory for successful device header file generation
      Other changes are related to some restructuring of the schema.

      Note that the memory section has been removed since this would limit the
      reuse of descriptions for a series of devices.
     -->

    <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="qualified" version="1.1">
      <!-- stringType requires a none empty string of a least one character length -->
      <xs:simpleType name="stringType">
        <xs:restriction base="xs:string">
          <xs:minLength value="1"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- cpuType specifies a selection of Cortex-M and Secure-Cores. This list will get extended as new processors are released -->
      <xs:simpleType name="cpuNameType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="CM0"/>
          <xs:enumeration value="CM0PLUS"/>
          <xs:enumeration value="CM0+"/>
          <xs:enumeration value="SC000"/>
          <xs:enumeration value="CM3"/>
          <xs:enumeration value="SC300"/>
          <xs:enumeration value="CM4"/>
          <xs:enumeration value="other"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- revisionType specifies the CPU revision format as defined by ARM (rNpM) -->
      <xs:simpleType name="revisionType">
        <xs:restriction base="xs:string">
          <xs:pattern value="r[0-9]p[0-9]"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- EndianType pre-defines the tokens for specifying the endianess of the device -->
      <xs:simpleType name="endianType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="little"/>
          <xs:enumeration value="big"/>
          <xs:enumeration value="selectable"/>
          <xs:enumeration value="other"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- dataType pre-defines the tokens in line with CMSIS data type definitions -->
      <xs:simpleType name="dataTypeType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="uint8_t"/>
          <xs:enumeration value="uint16_t"/>
          <xs:enumeration value="uint32_t"/>
          <xs:enumeration value="uint64_t"/>
          <xs:enumeration value="int8_t"/>
          <xs:enumeration value="int16_t"/>
          <xs:enumeration value="int32_t"/>
          <xs:enumeration value="int64_t"/>
          <xs:enumeration value="uint8_t *"/>
          <xs:enumeration value="uint16_t *"/>
          <xs:enumeration value="uint32_t *"/>
          <xs:enumeration value="uint64_t *"/>
          <xs:enumeration value="int8_t *"/>
          <xs:enumeration value="int16_t *"/>
          <xs:enumeration value="int32_t *"/>
          <xs:enumeration value="int64_t *"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- nvicPrioBitsType specifies the integer value range for the number of bits used in NVIC to encode priority levels -->
      <xs:simpleType name="nvicPrioBitsType">
        <xs:restriction base="xs:integer">
          <xs:minInclusive value="2"/>
          <xs:maxInclusive value="8"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- identifierType specifies the subset and sequence of characters used for specifying identifiers within the description. -->
      <!-- this is particularly important as these are used in ANSI C Structures during the device header file generation -->
      <xs:simpleType name="identifierType">
        <xs:restriction base="xs:string">
          <xs:pattern value="((%s)[_A-Za-z]{1}[_A-Za-z0-9]*)|([_A-Za-z]{1}[_A-Za-z0-9]*(\[%s\])?)|([_A-Za-z]{1}[_A-Za-z0-9]*(%s)?[_A-Za-z0-9]*)"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- enumerationNameType specifies the subset and sequence of characters used for specifying names of enumeratedValues. -->
      <!-- this is particularly important as these are used in ANSI C Structures during the device header file generation -->
      <xs:simpleType name="enumerationNameType">
        <xs:restriction base="xs:string">
          <xs:pattern value="[_A-Za-z0-9]*"/>
        </xs:restriction>
      </xs:simpleType>

      <!-- dimIndexType specifies the subset and sequence of characters used for specifying the sequence of indices in register arrays -->
      <xs:simpleType name="dimIndexType">
        <xs:restriction base="xs:string">
          <xs:pattern value="[0-9]+\-[0-9]+|[A-Z]-[A-Z]|[_0-9a-zA-Z]+(,\s*[_0-9a-zA-Z]+)+"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- scaledNonNegativeInteger specifies the format in which numbers are represented in hexadecimal or decimar format -->
      <xs:simpleType name="scaledNonNegativeInteger">
        <xs:restriction base="xs:string">
          <xs:pattern value="[+]?(0x|0X|#)?[0-9a-fA-F]+[kmgtKMGT]?"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- enumeratedValueDataType specifies the number formats for the values in enumeratedValues -->
      <xs:simpleType name="enumeratedValueDataType">
        <xs:restriction base="xs:string">
          <xs:pattern value="[+]?(0x|0X|#)?[0-9a-fxA-FX]+"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- accessType specfies the pre-defined tokens for the available accesses -->
      <xs:simpleType name="accessType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="read-only"/>
          <xs:enumeration value="write-only"/>
          <xs:enumeration value="read-write"/>
          <xs:enumeration value="writeOnce"/>
          <xs:enumeration value="read-writeOnce"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- modifiedWriteValuesType specifies the pre-defined tokens for the write side effects -->
      <xs:simpleType name="modifiedWriteValuesType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="oneToClear"/>
          <xs:enumeration value="oneToSet"/>
          <xs:enumeration value="oneToToggle"/>
          <xs:enumeration value="zeroToClear"/>
          <xs:enumeration value="zeroToSet"/>
          <xs:enumeration value="zeroToToggle"/>
          <xs:enumeration value="clear"/>
          <xs:enumeration value="set"/>
          <xs:enumeration value="modify"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- readAction type specifies the pre-defined tokens for read side effects -->
      <xs:simpleType name="readActionType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="clear"/>
          <xs:enumeration value="set"/>
          <xs:enumeration value="modify"/>
          <xs:enumeration value="modifyExternal"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- enumUsageType specifies the pre-defined tokens for selecting what access types an enumeratedValues set is associated with -->
      <xs:simpleType name="enumUsageType">
        <xs:restriction base="xs:token">
          <xs:enumeration value="read"/>
          <xs:enumeration value="write"/>
          <xs:enumeration value="read-write"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- bitRangeType specifies the bit numbers to be restricted values from 0 - 69 -->
      <xs:simpleType name="bitRangeType">
        <xs:restriction base="xs:token">
          <xs:pattern value="\[([0-4])?[0-9]:([0-4])?[0-9]\]"/>
        </xs:restriction>
      </xs:simpleType>
      <!-- writeContraintType specifies how to describe the restriction of the allowed values that can be written to a resource -->
      <xs:complexType name="writeConstraintType">
        <xs:choice>
          <xs:element name="writeAsRead" type="xs:boolean"/>
          <xs:element name="useEnumeratedValues" type="xs:boolean"/>
          <xs:element name="range">
            <xs:complexType>
              <xs:sequence>
                <xs:element name="minimum" type="scaledNonNegativeInteger"/>
                <xs:element name="maximum" type="scaledNonNegativeInteger"/>
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:choice>
      </xs:complexType>
      <!-- addressBlockType specifies the elements to describe an address block -->
      <xs:complexType name="addressBlockType">
        <xs:sequence>
          <xs:element name="offset" type="scaledNonNegativeInteger"/>
          <xs:element name="size" type="scaledNonNegativeInteger"/>
          <xs:element name="usage">
            <xs:simpleType>
              <xs:restriction base="xs:token">
                <xs:enumeration value="registers"/>
                <xs:enumeration value="buffer"/>
                <xs:enumeration value="reserved"/>
              </xs:restriction>
            </xs:simpleType>
          </xs:element>
        </xs:sequence>
      </xs:complexType>
      <!-- interruptType specifies how to describe an interrupt associated with a peripheral -->
      <xs:complexType name="interruptType">
        <xs:sequence>
          <xs:element name="name" type="stringType"/>
          <xs:element name="description" type="xs:string" minOccurs="0"/>
          <xs:element name="value" type="xs:integer"/>
        </xs:sequence>
      </xs:complexType>
      <!-- register properties group specifies register size, access permission and reset value
           this is used in multiple locations. Settings are inherited downstream. -->
      <xs:group name="registerPropertiesGroup">
        <xs:sequence>
          <xs:element name="size" type="scaledNonNegativeInteger" minOccurs="0"/>
          <xs:element name="access" type="accessType" minOccurs="0"/>
          <xs:element name="resetValue" type="scaledNonNegativeInteger" minOccurs="0"/>
          <xs:element name="resetMask" type="scaledNonNegativeInteger" minOccurs="0"/>
        </xs:sequence>
      </xs:group>
      <!-- bitRangeLsbMsbStyle specifies the bit position of a field within a register
           by specifying the least significant and the most significant bit position -->
      <xs:group name="bitRangeLsbMsbStyle">
        <xs:sequence>
          <xs:element name="lsb"  type="scaledNonNegativeInteger"/>
          <xs:element name="msb"  type="scaledNonNegativeInteger"/>
        </xs:sequence>
      </xs:group>
      <!-- bitRangeOffsetWidthStyle specifies the bit position of a field within a register
           by specifying the least significant bit position and the bitWidth of the field -->
      <xs:group name="bitRangeOffsetWidthStyle">
        <xs:sequence>
          <xs:element name="bitOffset" type="scaledNonNegativeInteger"/>
          <xs:element name="bitWidth" type="scaledNonNegativeInteger" minOccurs="0"/>
        </xs:sequence>
      </xs:group>
      <!-- dimElementGroup specifies the number of array elements (dim), the address offset
           between to consecutive array elements and an a comma seperated list of strings
           being used for identifying each element in the array -->
      <xs:group name="dimElementGroup">
        <xs:sequence>
          <xs:element name="dim" type="scaledNonNegativeInteger"/>
          <xs:element name="dimIncrement" type="scaledNonNegativeInteger"/>
          <xs:element name="dimIndex" type="dimIndexType" minOccurs="0"/>
        </xs:sequence>
      </xs:group>

      <xs:complexType name="cpuType">
        <xs:sequence>
          <!-- V1.1: ARM processor name: Cortex-Mx / SCxxx -->
          <xs:element name="name" type="cpuNameType"/>
          <!-- V1.1: ARM defined revision of the cpu -->
          <xs:element name="revision" type="revisionType"/>
          <!-- V1.1: Endian specifies the endianess of the processor/device -->
          <xs:element name="endian" type="endianType"/>
          <!-- V1.1: mpuPresent specifies whether or not a memory protection unit is physically present -->
          <xs:element name="mpuPresent" type="xs:boolean"/>
          <!-- V1.1: fpuPresent specifies whether or not a floating point hardware unit is physically present -->
          <xs:element name="fpuPresent" type="xs:boolean"/>
          <!-- V1.1: vtorPresent is used for Cortex-M0+ based devices only. It indicates whether the Vector Table Offset
                     Register is implemented in the device or not -->
          <xs:element name="vtorPresent" type="xs:boolean" minOccurs="0"/>
          <!-- V1.1: nvicPrioBits specifies the number of bits used by the Nested Vectored Interrupt Controller
                     for defining the priority level = # priority levels -->
          <xs:element name="nvicPrioBits" type="scaledNonNegativeInteger"/>
          <!-- V1.1: vendorSystickConfig is set true if a custom system timer is implemented in the device
                       instead of the ARM specified SysTickTimer -->
          <xs:element name="vendorSystickConfig" type="xs:boolean"/>
        </xs:sequence>
      </xs:complexType>

      <xs:complexType name="enumeratedValuesType">
        <xs:sequence>
          <!-- name specfies a reference to this enumeratedValues section for reuse purposes
               this name does not appear in the System Viewer nor the Header File. -->
          <xs:element name="name" type="enumerationNameType" minOccurs="0"/>
          <!-- usage specifies whether this enumeration is to be used for read or write or
                                                           (read and write) accesses -->
          <xs:element name="usage" type="enumUsageType" minOccurs="0"/>
          <!-- enumeratedValue derivedFrom=<identifierType> -->
          <xs:element name="enumeratedValue" minOccurs="1" maxOccurs="unbounded">
            <xs:complexType>
              <xs:sequence>
                <!-- name is a ANSI C indentifier representing the value (C Enumeration) -->
                <xs:element name="name" type="enumerationNameType"/>
                <!-- description contains the details about the semantics/behavior specified by this value -->
                <xs:element name="description" type="stringType" minOccurs="0"/>
                <xs:choice>
                  <xs:element name="value" type="enumeratedValueDataType"/>
                  <!-- isDefault specifies the name and description for all values that are not
                       specifically described individually -->
                  <xs:element name="isDefault" type="xs:boolean"/>
                </xs:choice>
              </xs:sequence>
            </xs:complexType>
          </xs:element>
        </xs:sequence>
        <xs:attribute name="derivedFrom" type="enumerationNameType" use="optional"/>
      </xs:complexType>

      <xs:complexType name="fieldType">
        <xs:sequence>
          <!-- name specifies a field's name. The System Viewer and the device header file will
               use the name of the field as identifier -->
          <xs:element name="name" type="identifierType"/>
          <!-- description contains reference manual level information about the function and
               options of a field -->
          <xs:element name="description" type="stringType" minOccurs="0"/>
          <!-- alternative specifications of the bit position of the field within the register -->
          <xs:choice minOccurs="1" maxOccurs="1">
            <!-- bit field described by lsb followed by msb tag -->
            <xs:group ref="bitRangeLsbMsbStyle"/>
            <!-- bit field described by bit offset relative to Bit0 + bit width of field -->
            <xs:group ref="bitRangeOffsetWidthStyle"/>
            <!-- bit field described by [<msb>:<lsb>] -->
            <xs:element name="bitRange" type="bitRangeType"/>
          </xs:choice>
          <!-- access describes the predefined permissions for the field. -->
          <xs:element name="access" type="accessType" minOccurs="0"/>
          <!-- predefined description of write side effects -->
          <xs:element name="modifiedWriteValues" type="modifiedWriteValuesType" minOccurs="0"/>
          <!-- writeContstraint specifies the subrange of allowed values -->
          <xs:element name="writeConstraint" type="writeConstraintType" minOccurs="0"/>
          <!-- readAction specifies the read side effects. -->
          <xs:element name="readAction" type="readActionType" minOccurs="0"/>
          <!-- enumeratedValues derivedFrom=<identifierType> -->
          <xs:element name="enumeratedValues" type="enumeratedValuesType" minOccurs="0" maxOccurs="2">
          </xs:element>
        </xs:sequence>
        <xs:attribute name="derivedFrom" type="identifierType" use="optional"/>
      </xs:complexType>

      <xs:complexType name="fieldsType">
        <xs:sequence>
          <!-- field derivedFrom=<identifierType> -->
          <xs:element name="field" type="fieldType" minOccurs="1" maxOccurs="unbounded"/>
        </xs:sequence>
      </xs:complexType>

      <xs:complexType name="registerType">
        <xs:sequence>
          <xs:group    ref="dimElementGroup" minOccurs="0"/>
          <!-- name specifies the name of the register. The register name is used by System Viewer and
                                         device header file generator to represent a register -->
          <xs:element name="name" type="identifierType"/>
          <!-- display name specifies a register name without the restritions of an ANSIS C identifier.
                                         The use of this tag is discouraged because it does not allow consistency between
                                         the System View and the device header file. -->
          <xs:element name="displayName" type="stringType" minOccurs="0"/>
          <!-- description contains a reference manual level description about the register and it's purpose -->
          <xs:element name="description" type="stringType" minOccurs="0"/>
          <xs:choice>
            <!-- alternateGroup specifies the identifier of the subgroup a register belongs to.
                                           This is useful if a register has a different description per mode but a single name -->
            <xs:element name="alternateGroup" type="identifierType" minOccurs="0"/>
            <!-- V1.1: alternateRegister specifies an alternate register description for an address that is
                                           already fully described. In this case the register name must be unique within the peripheral -->
            <xs:element name="alternateRegister" type="identifierType" minOccurs="0"/>
          </xs:choice>
          <!-- addressOffset describes the address of the register relative to the baseOffset of the peripheral -->
          <xs:element name="addressOffset" type="scaledNonNegativeInteger"/>
          <!-- registerPropertiesGroup elements specify the default values for register size, access permission and
                                         reset value. These default values are inherited to all fields contained in this register -->
          <xs:group    ref="registerPropertiesGroup" minOccurs="0"/>
          <!-- V1.1: dataType specifies a CMSIS compliant native dataType for a register (i.e. signed, unsigned, pointer) -->
          <xs:element name="dataType" type="dataTypeType" minOccurs="0"/>
          <!-- modifiedWriteValues specifies the write side effects -->
          <xs:element name="modifiedWriteValues" type="modifiedWriteValuesType" minOccurs="0"/>
          <!-- writeConstraint specifies the subset of allowed write values -->
          <xs:element name="writeConstraint" type="writeConstraintType" minOccurs="0"/>
          <!-- readAcction specifies the read side effects -->
          <xs:element name="readAction" type="readActionType" minOccurs="0"/>
          <!-- fields section contains all fields that belong to this register -->
          <xs:element name="fields" type="fieldsType" minOccurs="0" maxOccurs="1"/>
        </xs:sequence>
        <xs:attribute name="derivedFrom" type="identifierType" use="optional"/>
      </xs:complexType>

      <!-- V1.1: A cluster is a set of registers that are composed into a C data structure in the device header file -->
      <xs:complexType name="clusterType">
        <xs:sequence>
          <xs:group   ref="dimElementGroup" minOccurs="0"/>
          <xs:element name="name" type="identifierType"/>
          <xs:element name="description" type="xs:string"/>
          <!-- V1.1: alternateCluster specifies an alternative description for a cluster address range that is
                     already fully described. In this case the cluster name must be unique within the peripheral -->
          <xs:element name="alternateCluster" type="identifierType" minOccurs="0"/>
          <!-- V1.1: headerStructName specifies the name for the cluster structure typedef
                     used in the device header generation instead of the cluster name -->
          <xs:element name="headerStructName" type="identifierType" minOccurs="0"/>
          <xs:element name="addressOffset" type="scaledNonNegativeInteger"/>
          <xs:element name="register" type="registerType" minOccurs="1" maxOccurs="unbounded"/>
        </xs:sequence>
        <xs:attribute name="derivedFrom" type="identifierType" use="optional"/>
      </xs:complexType>

      <!-- the registers section can have an arbitrary list of cluster and register sections -->
      <xs:complexType name="registersType">
        <xs:choice minOccurs="1" maxOccurs="unbounded">
          <xs:element name="cluster" type="clusterType"/>
          <xs:element name="register" type="registerType"/>
        </xs:choice>
      </xs:complexType>

      <xs:complexType name="peripheralType">
        <xs:sequence>
          <!-- name specifies the name of a peripheral. This name is used for the System View and device header file -->
          <xs:element name="name" type="xs:Name"/>
          <!-- version specifies the version of the peripheral descriptions -->
          <xs:element name="version" type="stringType" minOccurs="0"/>
          <!-- description provides a high level functional description of the peripheral -->
          <xs:element name="description" type="stringType" minOccurs="0"/>
          <!-- V1.1: alternatePeripheral specifies an alternative description for an address range that is
               already fully by a peripheral described. In this case the peripheral name must be unique within the device description -->
          <xs:element name="alternatePeripheral" type="identifierType" minOccurs="0"/>
          <!-- groupName assigns this peripheral to a group of peripherals. This is only used bye the System View -->
          <xs:element name="groupName" type="xs:Name" minOccurs="0"/>
          <!-- prependToName specifies a prefix that is placed in front of each register name of this peripheral.
                             The device header file will show the registers in a C-Struct of the peripheral without the prefix. -->
          <xs:element name="prependToName" type="identifierType" minOccurs="0"/>
          <!-- appendToName is a postfix that is appended to each register name of this peripheral. The device header
                             file will sho the registers in a C-Struct of the peripheral without the postfix -->
          <xs:element name="appendToName" type="identifierType" minOccurs="0"/>
          <!-- V1.1: headerStructName specifies the name for the peripheral structure typedef
                             used in the device header generation instead of the peripheral name -->
          <xs:element name="headerStructName" type="identifierType" minOccurs="0"/>
          <!-- disableCondition contains a logical expression based on constants and register or bit-field values
                             if the condition is evaluated to true, the peripheral display will be disabled -->
          <xs:element name="disableCondition" type="stringType" minOccurs="0"/>
          <!-- baseAddress specifies the absolute base address of a peripheral. For derived peripherals it is mandatory
                             to specify a baseAddress. -->
          <xs:element name="baseAddress" type="scaledNonNegativeInteger"/>
          <!-- registerPropertiesGroup elements specify the default values for register size, access permission and
                             reset value. These default values are inherited to all registers contained in this peripheral -->
          <xs:group ref="registerPropertiesGroup" minOccurs="0"/>
          <!-- addressBlock specifies one or more address ranges that are assigned exclusively to this peripheral.
                             derived peripherals may have no addressBlock, however none-derived peripherals are required to specify
                             at least one address block -->
          <xs:element name="addressBlock" type="addressBlockType" minOccurs="0" maxOccurs="unbounded"/>
          <!-- interrupt specifies can specify one or more interrtupts by name, description and value -->
          <xs:element name="interrupt" type="interruptType" minOccurs="0" maxOccurs="unbounded"/>
          <!-- registers section contains all registers owned by the peripheral. In case a peripheral gets derived it does
                            not have its own registers section, hence this section is optional. A unique peripheral without a
                            registers section is not allowed -->
          <xs:element name="registers" type="registersType" minOccurs="0" maxOccurs="1">
          </xs:element>
        </xs:sequence>
        <xs:attribute name="derivedFrom" type="identifierType" use="optional"/>
      </xs:complexType>

      <!-- ==================================================== -->
      <!-- The top level element of a description is the device -->
      <!-- ==================================================== -->
      <xs:element name="device" nillable="true">
        <xs:complexType>
          <xs:sequence>
            <!-- V1.1: Vendor Name -->
            <xs:element name="vendor" type="stringType" minOccurs="0"/>
            <!-- V1.1: Vendor ID - a short name for referring to the vendor (e.g. Texas Instruments = TI) -->
            <xs:element name="vendorID" type="identifierType" minOccurs="0"/>
            <!-- name specifies the device name being described -->
            <xs:element name="name" type="identifierType"/>
            <!-- V1.1: series specifies the device series or family name -->
            <xs:element name="series" type="stringType" minOccurs="0"/>
            <!-- version specifies the version of the device description -->
            <xs:element name="version" type="stringType"/>
            <!-- description is a string describing the device features (e.g. memory size, peripherals, etc.) -->
            <xs:element name="description" type="stringType"/>
            <!-- V1.1: licenseText specifies the file header section to be included in any derived file -->
            <xs:element name="licenseText" type="stringType" minOccurs="0"/>
            <!-- V1.1: cpu specifies the details of the processor included in the device -->
            <xs:element name="cpu" type="cpuType" minOccurs="0"/>
            <!-- V1.1: the tag specifies the filename without extension of the CMSIS System Device include file.
                 This tag is used by the header file generator for customizing the include statement referencing the
                 CMSIS system file within the CMSIS device header file. By default the filename is "system_<device.name>"
                 In cases a device series shares a single system header file, the name of the series shall be used
                 instead of the individual device name. -->
            <xs:element name="headerSystemFilename" type="identifierType" minOccurs="0"/>
            <!-- V1.1: headerDefinitionPrefix specifies the string being prepended to all names of types defined in
                 generated device header file -->
            <xs:element name="headerDefinitionsPrefix" type="identifierType" minOccurs="0"/>
            <!-- addressUnitBits specifies the size of the minimal addressable unit in bits -->
            <xs:element name="addressUnitBits" type="scaledNonNegativeInteger"/>
            <!-- width specifies the number of bits for the maximum single transfer size allowed by the bus interface.
                 This sets the maximum size of a single register that can be defined for an address space -->
            <xs:element name="width" type="scaledNonNegativeInteger"/>
            <!-- registerPropertiesGroup elements specify the default values for register size, access permission and
                 reset value -->
            <xs:group ref="registerPropertiesGroup" minOccurs="0"/>

            <!-- peripherals is containing all peripherals -->
            <xs:element name="peripherals">
              <xs:complexType>
                <xs:sequence>
                  <xs:element name="peripheral" type="peripheralType" minOccurs="1" maxOccurs="unbounded"/>
                </xs:sequence>
              </xs:complexType>
            </xs:element>

            <!-- Vendor Extensions: this section captures custom extensions. This section will be ignored by default -->
            <xs:element name="vendorExtensions" minOccurs="0" maxOccurs="1">
              <xs:complexType>
                <xs:sequence>
                  <xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded">
                  </xs:any>
                </xs:sequence>
              </xs:complexType>
            </xs:element>
          </xs:sequence>
          <xs:attribute name="schemaVersion" type="xs:decimal" use="required" fixed="1.1"/>
        </xs:complexType>
      </xs:element>
    </xs:schema>