diff --git a/Marlin/Sd2Card.cpp b/Marlin/Sd2Card.cpp
index 74de29b9d..ce07846f1 100644
--- a/Marlin/Sd2Card.cpp
+++ b/Marlin/Sd2Card.cpp
@@ -55,7 +55,7 @@
   //------------------------------------------------------------------------------
   /** SPI receive a byte */
   static uint8_t spiRec() {
-    SPDR = 0XFF;
+    SPDR = 0xFF;
     while (!TEST(SPSR, SPIF)) { /* Intentionally left empty */ }
     return SPDR;
   }
@@ -64,11 +64,11 @@
   static inline __attribute__((always_inline))
   void spiRead(uint8_t* buf, uint16_t nbyte) {
     if (nbyte-- == 0) return;
-    SPDR = 0XFF;
+    SPDR = 0xFF;
     for (uint16_t i = 0; i < nbyte; i++) {
       while (!TEST(SPSR, SPIF)) { /* Intentionally left empty */ }
       buf[i] = SPDR;
-      SPDR = 0XFF;
+      SPDR = 0xFF;
     }
     while (!TEST(SPSR, SPIF)) { /* Intentionally left empty */ }
     buf[nbyte] = SPDR;
@@ -103,7 +103,7 @@
     uint8_t data = 0;
     // no interrupts during byte receive - about 8 us
     cli();
-    // output pin high - like sending 0XFF
+    // output pin high - like sending 0xFF
     WRITE(SPI_MOSI_PIN, HIGH);
 
     for (uint8_t i = 0; i < 8; i++) {
@@ -137,7 +137,7 @@
     for (uint8_t i = 0; i < 8; i++) {
       WRITE(SPI_SCK_PIN, LOW);
 
-      WRITE(SPI_MOSI_PIN, data & 0X80);
+      WRITE(SPI_MOSI_PIN, data & 0x80);
 
       data <<= 1;
 
@@ -177,16 +177,16 @@ uint8_t Sd2Card::cardCommand(uint8_t cmd, uint32_t arg) {
   for (int8_t s = 24; s >= 0; s -= 8) spiSend(arg >> s);
 
   // send CRC
-  uint8_t crc = 0XFF;
-  if (cmd == CMD0) crc = 0X95;  // correct crc for CMD0 with arg 0
-  if (cmd == CMD8) crc = 0X87;  // correct crc for CMD8 with arg 0X1AA
+  uint8_t crc = 0xFF;
+  if (cmd == CMD0) crc = 0x95;  // correct crc for CMD0 with arg 0
+  if (cmd == CMD8) crc = 0x87;  // correct crc for CMD8 with arg 0x1AA
   spiSend(crc);
 
   // skip stuff byte for stop read
   if (cmd == CMD12) spiRec();
 
   // wait for response
-  for (uint8_t i = 0; ((status_ = spiRec()) & 0X80) && i != 0XFF; i++) { /* Intentionally left empty */ }
+  for (uint8_t i = 0; ((status_ = spiRec()) & 0x80) && i != 0xFF; i++) { /* Intentionally left empty */ }
   return status_;
 }
 //------------------------------------------------------------------------------
@@ -329,7 +329,7 @@ bool Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
   #endif  // SOFTWARE_SPI
 
   // must supply min of 74 clock cycles with CS high.
-  for (uint8_t i = 0; i < 10; i++) spiSend(0XFF);
+  for (uint8_t i = 0; i < 10; i++) spiSend(0xFF);
 
   // command to go idle in SPI mode
   while ((status_ = cardCommand(CMD0, 0)) != R1_IDLE_STATE) {
@@ -345,14 +345,14 @@ bool Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
   else {
     // only need last byte of r7 response
     for (uint8_t i = 0; i < 4; i++) status_ = spiRec();
-    if (status_ != 0XAA) {
+    if (status_ != 0xAA) {
       error(SD_CARD_ERROR_CMD8);
       goto fail;
     }
     type(SD_CARD_TYPE_SD2);
   }
   // initialize card and send host supports SDHC if SD2
-  arg = type() == SD_CARD_TYPE_SD2 ? 0X40000000 : 0;
+  arg = type() == SD_CARD_TYPE_SD2 ? 0x40000000 : 0;
 
   while ((status_ = cardAcmd(ACMD41, arg)) != R1_READY_STATE) {
     // check for timeout
@@ -367,7 +367,7 @@ bool Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
       error(SD_CARD_ERROR_CMD58);
       goto fail;
     }
-    if ((spiRec() & 0XC0) == 0XC0) type(SD_CARD_TYPE_SDHC);
+    if ((spiRec() & 0xC0) == 0xC0) type(SD_CARD_TYPE_SDHC);
     // discard rest of ocr - contains allowed voltage range
     for (uint8_t i = 0; i < 3; i++) spiRec();
   }
@@ -473,7 +473,7 @@ static const uint16_t crctab[] PROGMEM = {
 static uint16_t CRC_CCITT(const uint8_t* data, size_t n) {
   uint16_t crc = 0;
   for (size_t i = 0; i < n; i++) {
-    crc = pgm_read_word(&crctab[(crc >> 8 ^ data[i]) & 0XFF]) ^ (crc << 8);
+    crc = pgm_read_word(&crctab[(crc >> 8 ^ data[i]) & 0xFF]) ^ (crc << 8);
   }
   return crc;
 }
diff --git a/Marlin/Sd2Card.h b/Marlin/Sd2Card.h
index f91958ac0..1fbd52747 100644
--- a/Marlin/Sd2Card.h
+++ b/Marlin/Sd2Card.h
@@ -92,27 +92,27 @@ uint8_t const SD_CARD_ERROR_ERASE_TIMEOUT = 0XE;
 /** card returned an error token instead of read data */
 uint8_t const SD_CARD_ERROR_READ = 0XF;
 /** read CID or CSD failed */
-uint8_t const SD_CARD_ERROR_READ_REG = 0X10;
+uint8_t const SD_CARD_ERROR_READ_REG = 0x10;
 /** timeout while waiting for start of read data */
-uint8_t const SD_CARD_ERROR_READ_TIMEOUT = 0X11;
+uint8_t const SD_CARD_ERROR_READ_TIMEOUT = 0x11;
 /** card did not accept STOP_TRAN_TOKEN */
-uint8_t const SD_CARD_ERROR_STOP_TRAN = 0X12;
+uint8_t const SD_CARD_ERROR_STOP_TRAN = 0x12;
 /** card returned an error token as a response to a write operation */
-uint8_t const SD_CARD_ERROR_WRITE = 0X13;
+uint8_t const SD_CARD_ERROR_WRITE = 0x13;
 /** attempt to write protected block zero */
-uint8_t const SD_CARD_ERROR_WRITE_BLOCK_ZERO = 0X14;  // REMOVE - not used
+uint8_t const SD_CARD_ERROR_WRITE_BLOCK_ZERO = 0x14;  // REMOVE - not used
 /** card did not go ready for a multiple block write */
-uint8_t const SD_CARD_ERROR_WRITE_MULTIPLE = 0X15;
+uint8_t const SD_CARD_ERROR_WRITE_MULTIPLE = 0x15;
 /** card returned an error to a CMD13 status check after a write */
-uint8_t const SD_CARD_ERROR_WRITE_PROGRAMMING = 0X16;
+uint8_t const SD_CARD_ERROR_WRITE_PROGRAMMING = 0x16;
 /** timeout occurred during write programming */
-uint8_t const SD_CARD_ERROR_WRITE_TIMEOUT = 0X17;
+uint8_t const SD_CARD_ERROR_WRITE_TIMEOUT = 0x17;
 /** incorrect rate selected */
-uint8_t const SD_CARD_ERROR_SCK_RATE = 0X18;
+uint8_t const SD_CARD_ERROR_SCK_RATE = 0x18;
 /** init() not called */
-uint8_t const SD_CARD_ERROR_INIT_NOT_CALLED = 0X19;
+uint8_t const SD_CARD_ERROR_INIT_NOT_CALLED = 0x19;
 /** crc check error */
-uint8_t const SD_CARD_ERROR_CRC = 0X20;
+uint8_t const SD_CARD_ERROR_CRC = 0x20;
 //------------------------------------------------------------------------------
 // card types
 /** Standard capacity V1 SD card */
diff --git a/Marlin/SdBaseFile.cpp b/Marlin/SdBaseFile.cpp
index 97b4fa00f..0dc165cd6 100644
--- a/Marlin/SdBaseFile.cpp
+++ b/Marlin/SdBaseFile.cpp
@@ -57,7 +57,7 @@ bool SdBaseFile::addCluster() {
 bool SdBaseFile::addDirCluster() {
   uint32_t block;
   // max folder size
-  if (fileSize_ / sizeof(dir_t) >= 0XFFFF) goto fail;
+  if (fileSize_ / sizeof(dir_t) >= 0xFFFF) goto fail;
 
   if (!addCluster()) goto fail;
   if (!vol_->cacheFlush()) goto fail;
@@ -510,7 +510,7 @@ bool SdBaseFile::mkdir(SdBaseFile* parent, const uint8_t dname[11]) {
     d.firstClusterHigh = 0;
   }
   else {
-    d.firstClusterLow = parent->firstCluster_ & 0XFFFF;
+    d.firstClusterLow = parent->firstCluster_ & 0xFFFF;
     d.firstClusterHigh = parent->firstCluster_ >> 16;
   }
   // copy '..' to block
@@ -1063,7 +1063,7 @@ int16_t SdBaseFile::read(void* buf, uint16_t nbyte) {
   // amount left to read
   toRead = nbyte;
   while (toRead > 0) {
-    offset = curPosition_ & 0X1FF;  // offset in block
+    offset = curPosition_ & 0x1FF;  // offset in block
     if (type_ == FAT_FILE_TYPE_ROOT_FIXED) {
       block = vol_->rootDirStart() + (curPosition_ >> 9);
     }
@@ -1120,7 +1120,7 @@ fail:
 int8_t SdBaseFile::readDir(dir_t* dir, char* longFilename) {
   int16_t n;
   // if not a directory file or miss-positioned return an error
-  if (!isDir() || (0X1F & curPosition_)) return -1;
+  if (!isDir() || (0x1F & curPosition_)) return -1;
 
   //If we have a longFilename buffer, mark it as invalid. If we find a long filename it will be filled automaticly.
   if (longFilename != NULL) longFilename[0] = '\0';
@@ -1513,7 +1513,7 @@ bool SdBaseFile::sync() {
     if (!isDir()) d->fileSize = fileSize_;
 
     // update first cluster fields
-    d->firstClusterLow = firstCluster_ & 0XFFFF;
+    d->firstClusterLow = firstCluster_ & 0xFFFF;
     d->firstClusterHigh = firstCluster_ >> 16;
 
     // set modify time if user supplied a callback date/time function
@@ -1738,7 +1738,7 @@ int16_t SdBaseFile::write(const void* buf, uint16_t nbyte) {
 
   while (nToWrite > 0) {
     uint8_t blockOfCluster = vol_->blockOfCluster(curPosition_);
-    uint16_t blockOffset = curPosition_ & 0X1FF;
+    uint16_t blockOffset = curPosition_ & 0x1FF;
     if (blockOfCluster == 0 && blockOffset == 0) {
       // start of new cluster
       if (curCluster_ == 0) {
@@ -1774,7 +1774,7 @@ int16_t SdBaseFile::write(const void* buf, uint16_t nbyte) {
       // full block - don't need to use cache
       if (vol_->cacheBlockNumber() == block) {
         // invalidate cache if block is in cache
-        vol_->cacheSetBlockNumber(0XFFFFFFFF, false);
+        vol_->cacheSetBlockNumber(0xFFFFFFFF, false);
       }
       if (!vol_->writeBlock(block, src)) goto fail;
     }
diff --git a/Marlin/SdBaseFile.h b/Marlin/SdBaseFile.h
index 02ab70543..02daa7b7f 100644
--- a/Marlin/SdBaseFile.h
+++ b/Marlin/SdBaseFile.h
@@ -54,11 +54,11 @@ struct filepos_t {
 
 // use the gnu style oflag in open()
 /** open() oflag for reading */
-uint8_t const O_READ = 0X01;
+uint8_t const O_READ = 0x01;
 /** open() oflag - same as O_IN */
 uint8_t const O_RDONLY = O_READ;
 /** open() oflag for write */
-uint8_t const O_WRITE = 0X02;
+uint8_t const O_WRITE = 0x02;
 /** open() oflag - same as O_WRITE */
 uint8_t const O_WRONLY = O_WRITE;
 /** open() oflag for reading and writing */
@@ -66,17 +66,17 @@ uint8_t const O_RDWR = (O_READ | O_WRITE);
 /** open() oflag mask for access modes */
 uint8_t const O_ACCMODE = (O_READ | O_WRITE);
 /** The file offset shall be set to the end of the file prior to each write. */
-uint8_t const O_APPEND = 0X04;
+uint8_t const O_APPEND = 0x04;
 /** synchronous writes - call sync() after each write */
-uint8_t const O_SYNC = 0X08;
+uint8_t const O_SYNC = 0x08;
 /** truncate the file to zero length */
-uint8_t const O_TRUNC = 0X10;
+uint8_t const O_TRUNC = 0x10;
 /** set the initial position at the end of the file */
-uint8_t const O_AT_END = 0X20;
+uint8_t const O_AT_END = 0x20;
 /** create the file if nonexistent */
-uint8_t const O_CREAT = 0X40;
+uint8_t const O_CREAT = 0x40;
 /** If O_CREAT and O_EXCL are set, open() shall fail if the file exists */
-uint8_t const O_EXCL = 0X80;
+uint8_t const O_EXCL = 0x80;
 
 // SdBaseFile class static and const definitions
 // flags for ls()
@@ -141,7 +141,7 @@ static inline uint8_t FAT_MONTH(uint16_t fatDate) {
  * \return Extracted day [1,31]
  */
 static inline uint8_t FAT_DAY(uint16_t fatDate) {
-  return fatDate & 0X1F;
+  return fatDate & 0x1F;
 }
 /** time field for FAT directory entry
  * \param[in] hour [0,23]
@@ -167,7 +167,7 @@ static inline uint8_t FAT_HOUR(uint16_t fatTime) {
  * \return Extracted minute [0,59]
  */
 static inline uint8_t FAT_MINUTE(uint16_t fatTime) {
-  return (fatTime >> 5) & 0X3F;
+  return (fatTime >> 5) & 0x3F;
 }
 /** second part of FAT directory time field
  * Note second/2 is stored in packed time.
@@ -177,7 +177,7 @@ static inline uint8_t FAT_MINUTE(uint16_t fatTime) {
  * \return Extracted second [0,58]
  */
 static inline uint8_t FAT_SECOND(uint16_t fatTime) {
-  return 2 * (fatTime & 0X1F);
+  return 2 * (fatTime & 0x1F);
 }
 /** Default date for file timestamps is 1 Jan 2000 */
 uint16_t const FAT_DEFAULT_DATE = ((2000 - 1980) << 9) | (1 << 5) | 1;
@@ -338,10 +338,10 @@ class SdBaseFile {
   // data time callback function
   static void (*dateTime_)(uint16_t* date, uint16_t* time);
   // bits defined in flags_
-  // should be 0X0F
+  // should be 0x0F
   static uint8_t const F_OFLAG = (O_ACCMODE | O_APPEND | O_SYNC);
   // sync of directory entry required
-  static uint8_t const F_FILE_DIR_DIRTY = 0X80;
+  static uint8_t const F_FILE_DIR_DIRTY = 0x80;
 
   // private data
   uint8_t   flags_;         // See above for definition of flags_ bits
diff --git a/Marlin/SdFatStructs.h b/Marlin/SdFatStructs.h
index 3e78aa292..52c815d76 100644
--- a/Marlin/SdFatStructs.h
+++ b/Marlin/SdFatStructs.h
@@ -43,11 +43,11 @@
  */
 //------------------------------------------------------------------------------
 /** Value for byte 510 of boot block or MBR */
-uint8_t const BOOTSIG0 = 0X55;
+uint8_t const BOOTSIG0 = 0x55;
 /** Value for byte 511 of boot block or MBR */
-uint8_t const BOOTSIG1 = 0XAA;
+uint8_t const BOOTSIG1 = 0xAA;
 /** Value for bootSignature field int FAT/FAT32 boot sector */
-uint8_t const EXTENDED_BOOT_SIG = 0X29;
+uint8_t const EXTENDED_BOOT_SIG = 0x29;
 //------------------------------------------------------------------------------
 /**
  * \struct partitionTable
@@ -59,8 +59,8 @@ uint8_t const EXTENDED_BOOT_SIG = 0X29;
 struct partitionTable {
           /**
            * Boot Indicator . Indicates whether the volume is the active
-           * partition.  Legal values include: 0X00. Do not use for booting.
-           * 0X80 Active partition.
+           * partition.  Legal values include: 0x00. Do not use for booting.
+           * 0x80 Active partition.
            */
   uint8_t  boot;
           /**
@@ -126,9 +126,9 @@ struct masterBootRecord {
   uint16_t usuallyZero;
            /** Partition tables. */
   part_t   part[4];
-           /** First MBR signature byte. Must be 0X55 */
+           /** First MBR signature byte. Must be 0x55 */
   uint8_t  mbrSig0;
-           /** Second MBR signature byte. Must be 0XAA */
+           /** Second MBR signature byte. Must be 0xAA */
   uint8_t  mbrSig1;
 } PACKED;
 /** Type name for masterBootRecord */
@@ -234,7 +234,7 @@ struct fat_boot {
   uint8_t  driveNumber;
            /** used by Windows NT - should be zero for FAT */
   uint8_t  reserved1;
-           /** 0X29 if next three fields are valid */
+           /** 0x29 if next three fields are valid */
   uint8_t  bootSignature;
            /**
             * A random serial number created when formatting a disk,
@@ -254,9 +254,9 @@ struct fat_boot {
   char     fileSystemType[8];
            /** X86 boot code */
   uint8_t  bootCode[448];
-           /** must be 0X55 */
+           /** must be 0x55 */
   uint8_t  bootSectorSig0;
-           /** must be 0XAA */
+           /** must be 0xAA */
   uint8_t  bootSectorSig1;
 } PACKED;
 /** Type name for FAT Boot Sector */
@@ -389,7 +389,7 @@ struct fat32_boot {
   uint8_t  driveNumber;
            /** used by Windows NT - should be zero for FAT */
   uint8_t  reserved1;
-           /** 0X29 if next three fields are valid */
+           /** 0x29 if next three fields are valid */
   uint8_t  bootSignature;
            /**
             * A random serial number created when formatting a disk,
@@ -408,9 +408,9 @@ struct fat32_boot {
   char     fileSystemType[8];
            /** X86 boot code */
   uint8_t  bootCode[420];
-           /** must be 0X55 */
+           /** must be 0x55 */
   uint8_t  bootSectorSig0;
-           /** must be 0XAA */
+           /** must be 0xAA */
   uint8_t  bootSectorSig1;
 } PACKED;
 /** Type name for FAT32 Boot Sector */
@@ -427,11 +427,11 @@ uint32_t const FSINFO_STRUCT_SIG = 0x61417272;
  *
  */
 struct fat32_fsinfo {
-           /** must be 0X52, 0X52, 0X61, 0X41 */
+           /** must be 0x52, 0x52, 0x61, 0x41 */
   uint32_t  leadSignature;
            /** must be zero */
   uint8_t  reserved1[480];
-           /** must be 0X72, 0X72, 0X41, 0X61 */
+           /** must be 0x72, 0x72, 0x41, 0x61 */
   uint32_t  structSignature;
           /**
            * Contains the last known free cluster count on the volume.
@@ -450,7 +450,7 @@ struct fat32_fsinfo {
   uint32_t nextFree;
            /** must be zero */
   uint8_t  reserved2[12];
-           /** must be 0X00, 0X00, 0X55, 0XAA */
+           /** must be 0x00, 0x00, 0x55, 0xAA */
   uint8_t  tailSignature[4];
 } PACKED;
 /** Type name for FAT32 FSINFO Sector */
@@ -458,19 +458,19 @@ typedef struct fat32_fsinfo fat32_fsinfo_t;
 //------------------------------------------------------------------------------
 // End Of Chain values for FAT entries
 /** FAT12 end of chain value used by Microsoft. */
-uint16_t const FAT12EOC = 0XFFF;
+uint16_t const FAT12EOC = 0xFFF;
 /** Minimum value for FAT12 EOC.  Use to test for EOC. */
-uint16_t const FAT12EOC_MIN = 0XFF8;
+uint16_t const FAT12EOC_MIN = 0xFF8;
 /** FAT16 end of chain value used by Microsoft. */
-uint16_t const FAT16EOC = 0XFFFF;
+uint16_t const FAT16EOC = 0xFFFF;
 /** Minimum value for FAT16 EOC.  Use to test for EOC. */
-uint16_t const FAT16EOC_MIN = 0XFFF8;
+uint16_t const FAT16EOC_MIN = 0xFFF8;
 /** FAT32 end of chain value used by Microsoft. */
-uint32_t const FAT32EOC = 0X0FFFFFFF;
+uint32_t const FAT32EOC = 0x0FFFFFFF;
 /** Minimum value for FAT32 EOC.  Use to test for EOC. */
-uint32_t const FAT32EOC_MIN = 0X0FFFFFF8;
+uint32_t const FAT32EOC_MIN = 0x0FFFFFF8;
 /** Mask a for FAT32 entry. Entries are 28 bits. */
-uint32_t const FAT32MASK = 0X0FFFFFFF;
+uint32_t const FAT32MASK = 0x0FFFFFFF;
 //------------------------------------------------------------------------------
 /**
  * \struct directoryEntry
@@ -590,31 +590,31 @@ struct directoryVFATEntry {
 typedef struct directoryEntry dir_t;
 /** Type name for directoryVFATEntry */
 typedef struct directoryVFATEntry vfat_t;
-/** escape for name[0] = 0XE5 */
-uint8_t const DIR_NAME_0XE5 = 0X05;
+/** escape for name[0] = 0xE5 */
+uint8_t const DIR_NAME_0xE5 = 0x05;
 /** name[0] value for entry that is free after being "deleted" */
-uint8_t const DIR_NAME_DELETED = 0XE5;
+uint8_t const DIR_NAME_DELETED = 0xE5;
 /** name[0] value for entry that is free and no allocated entries follow */
-uint8_t const DIR_NAME_FREE = 0X00;
+uint8_t const DIR_NAME_FREE = 0x00;
 /** file is read-only */
-uint8_t const DIR_ATT_READ_ONLY = 0X01;
+uint8_t const DIR_ATT_READ_ONLY = 0x01;
 /** File should hidden in directory listings */
-uint8_t const DIR_ATT_HIDDEN = 0X02;
+uint8_t const DIR_ATT_HIDDEN = 0x02;
 /** Entry is for a system file */
-uint8_t const DIR_ATT_SYSTEM = 0X04;
+uint8_t const DIR_ATT_SYSTEM = 0x04;
 /** Directory entry contains the volume label */
-uint8_t const DIR_ATT_VOLUME_ID = 0X08;
+uint8_t const DIR_ATT_VOLUME_ID = 0x08;
 /** Entry is for a directory */
-uint8_t const DIR_ATT_DIRECTORY = 0X10;
+uint8_t const DIR_ATT_DIRECTORY = 0x10;
 /** Old DOS archive bit for backup support */
-uint8_t const DIR_ATT_ARCHIVE = 0X20;
+uint8_t const DIR_ATT_ARCHIVE = 0x20;
 /** Test value for long name entry.  Test is
   (d->attributes & DIR_ATT_LONG_NAME_MASK) == DIR_ATT_LONG_NAME. */
-uint8_t const DIR_ATT_LONG_NAME = 0X0F;
+uint8_t const DIR_ATT_LONG_NAME = 0x0F;
 /** Test mask for long name entry */
-uint8_t const DIR_ATT_LONG_NAME_MASK = 0X3F;
+uint8_t const DIR_ATT_LONG_NAME_MASK = 0x3F;
 /** defined attribute bits */
-uint8_t const DIR_ATT_DEFINED_BITS = 0X3F;
+uint8_t const DIR_ATT_DEFINED_BITS = 0x3F;
 /** Directory entry is part of a long name
  * \param[in] dir Pointer to a directory entry.
  *
diff --git a/Marlin/SdInfo.h b/Marlin/SdInfo.h
index f4b36b7ae..88b465690 100644
--- a/Marlin/SdInfo.h
+++ b/Marlin/SdInfo.h
@@ -45,59 +45,59 @@
 //------------------------------------------------------------------------------
 // SD card commands
 /** GO_IDLE_STATE - init card in spi mode if CS low */
-uint8_t const CMD0 = 0X00;
+uint8_t const CMD0 = 0x00;
 /** SEND_IF_COND - verify SD Memory Card interface operating condition.*/
-uint8_t const CMD8 = 0X08;
+uint8_t const CMD8 = 0x08;
 /** SEND_CSD - read the Card Specific Data (CSD register) */
-uint8_t const CMD9 = 0X09;
+uint8_t const CMD9 = 0x09;
 /** SEND_CID - read the card identification information (CID register) */
-uint8_t const CMD10 = 0X0A;
+uint8_t const CMD10 = 0x0A;
 /** STOP_TRANSMISSION - end multiple block read sequence */
-uint8_t const CMD12 = 0X0C;
+uint8_t const CMD12 = 0x0C;
 /** SEND_STATUS - read the card status register */
-uint8_t const CMD13 = 0X0D;
+uint8_t const CMD13 = 0x0D;
 /** READ_SINGLE_BLOCK - read a single data block from the card */
-uint8_t const CMD17 = 0X11;
+uint8_t const CMD17 = 0x11;
 /** READ_MULTIPLE_BLOCK - read a multiple data blocks from the card */
-uint8_t const CMD18 = 0X12;
+uint8_t const CMD18 = 0x12;
 /** WRITE_BLOCK - write a single data block to the card */
-uint8_t const CMD24 = 0X18;
+uint8_t const CMD24 = 0x18;
 /** WRITE_MULTIPLE_BLOCK - write blocks of data until a STOP_TRANSMISSION */
-uint8_t const CMD25 = 0X19;
+uint8_t const CMD25 = 0x19;
 /** ERASE_WR_BLK_START - sets the address of the first block to be erased */
-uint8_t const CMD32 = 0X20;
+uint8_t const CMD32 = 0x20;
 /** ERASE_WR_BLK_END - sets the address of the last block of the continuous
     range to be erased*/
-uint8_t const CMD33 = 0X21;
+uint8_t const CMD33 = 0x21;
 /** ERASE - erase all previously selected blocks */
-uint8_t const CMD38 = 0X26;
+uint8_t const CMD38 = 0x26;
 /** APP_CMD - escape for application specific command */
-uint8_t const CMD55 = 0X37;
+uint8_t const CMD55 = 0x37;
 /** READ_OCR - read the OCR register of a card */
-uint8_t const CMD58 = 0X3A;
+uint8_t const CMD58 = 0x3A;
 /** SET_WR_BLK_ERASE_COUNT - Set the number of write blocks to be
      pre-erased before writing */
-uint8_t const ACMD23 = 0X17;
+uint8_t const ACMD23 = 0x17;
 /** SD_SEND_OP_COMD - Sends host capacity support information and
     activates the card's initialization process */
-uint8_t const ACMD41 = 0X29;
+uint8_t const ACMD41 = 0x29;
 //------------------------------------------------------------------------------
 /** status for card in the ready state */
-uint8_t const R1_READY_STATE = 0X00;
+uint8_t const R1_READY_STATE = 0x00;
 /** status for card in the idle state */
-uint8_t const R1_IDLE_STATE = 0X01;
+uint8_t const R1_IDLE_STATE = 0x01;
 /** status bit for illegal command */
-uint8_t const R1_ILLEGAL_COMMAND = 0X04;
+uint8_t const R1_ILLEGAL_COMMAND = 0x04;
 /** start data token for read or write single block*/
-uint8_t const DATA_START_BLOCK = 0XFE;
+uint8_t const DATA_START_BLOCK = 0xFE;
 /** stop token for write multiple blocks*/
-uint8_t const STOP_TRAN_TOKEN = 0XFD;
+uint8_t const STOP_TRAN_TOKEN = 0xFD;
 /** start data token for write multiple blocks*/
-uint8_t const WRITE_MULTIPLE_TOKEN = 0XFC;
+uint8_t const WRITE_MULTIPLE_TOKEN = 0xFC;
 /** mask for data response tokens after a write block operation */
-uint8_t const DATA_RES_MASK = 0X1F;
+uint8_t const DATA_RES_MASK = 0x1F;
 /** write data accepted token */
-uint8_t const DATA_RES_ACCEPTED = 0X05;
+uint8_t const DATA_RES_ACCEPTED = 0x05;
 //------------------------------------------------------------------------------
 /** Card IDentification (CID) register */
 typedef struct CID {
@@ -203,7 +203,7 @@ typedef struct CSDV2 {
   unsigned char reserved1 : 6;
   unsigned char csd_ver : 2;
   // byte 1
-  /** fixed to 0X0E */
+  /** fixed to 0x0E */
   unsigned char taac;
   // byte 2
   /** fixed to 0 */
diff --git a/Marlin/SdVolume.cpp b/Marlin/SdVolume.cpp
index 4166c0661..701b116c2 100644
--- a/Marlin/SdVolume.cpp
+++ b/Marlin/SdVolume.cpp
@@ -167,7 +167,7 @@ bool SdVolume::fatGet(uint32_t cluster, uint32_t* value) {
     index += index >> 1;
     lba = fatStartBlock_ + (index >> 9);
     if (!cacheRawBlock(lba, CACHE_FOR_READ)) goto fail;
-    index &= 0X1FF;
+    index &= 0x1FF;
     uint16_t tmp = cacheBuffer_.data[index];
     index++;
     if (index == 512) {
@@ -175,7 +175,7 @@ bool SdVolume::fatGet(uint32_t cluster, uint32_t* value) {
       index = 0;
     }
     tmp |= cacheBuffer_.data[index] << 8;
-    *value = cluster & 1 ? tmp >> 4 : tmp & 0XFFF;
+    *value = cluster & 1 ? tmp >> 4 : tmp & 0xFFF;
     return true;
   }
   if (fatType_ == 16) {
@@ -191,10 +191,10 @@ bool SdVolume::fatGet(uint32_t cluster, uint32_t* value) {
     if (!cacheRawBlock(lba, CACHE_FOR_READ)) goto fail;
   }
   if (fatType_ == 16) {
-    *value = cacheBuffer_.fat16[cluster & 0XFF];
+    *value = cacheBuffer_.fat16[cluster & 0xFF];
   }
   else {
-    *value = cacheBuffer_.fat32[cluster & 0X7F] & FAT32MASK;
+    *value = cacheBuffer_.fat32[cluster & 0x7F] & FAT32MASK;
   }
   return true;
 fail:
@@ -217,7 +217,7 @@ bool SdVolume::fatPut(uint32_t cluster, uint32_t value) {
     if (!cacheRawBlock(lba, CACHE_FOR_WRITE)) goto fail;
     // mirror second FAT
     if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
-    index &= 0X1FF;
+    index &= 0x1FF;
     uint8_t tmp = value;
     if (cluster & 1) {
       tmp = (cacheBuffer_.data[index] & 0XF) | tmp << 4;
@@ -233,7 +233,7 @@ bool SdVolume::fatPut(uint32_t cluster, uint32_t value) {
     }
     tmp = value >> 4;
     if (!(cluster & 1)) {
-      tmp = ((cacheBuffer_.data[index] & 0XF0)) | tmp >> 4;
+      tmp = ((cacheBuffer_.data[index] & 0xF0)) | tmp >> 4;
     }
     cacheBuffer_.data[index] = tmp;
     return true;
@@ -250,10 +250,10 @@ bool SdVolume::fatPut(uint32_t cluster, uint32_t value) {
   if (!cacheRawBlock(lba, CACHE_FOR_WRITE)) goto fail;
   // store entry
   if (fatType_ == 16) {
-    cacheBuffer_.fat16[cluster & 0XFF] = value;
+    cacheBuffer_.fat16[cluster & 0xFF] = value;
   }
   else {
-    cacheBuffer_.fat32[cluster & 0X7F] = value;
+    cacheBuffer_.fat32[cluster & 0x7F] = value;
   }
   // mirror second FAT
   if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
@@ -344,7 +344,7 @@ bool SdVolume::init(Sd2Card* dev, uint8_t part) {
   allocSearchStart_ = 2;
   cacheDirty_ = 0;  // cacheFlush() will write block if true
   cacheMirrorBlock_ = 0;
-  cacheBlockNumber_ = 0XFFFFFFFF;
+  cacheBlockNumber_ = 0xFFFFFFFF;
 
   // if part == 0 assume super floppy with FAT boot sector in block zero
   // if part > 0 assume mbr volume with partition table
@@ -352,7 +352,7 @@ bool SdVolume::init(Sd2Card* dev, uint8_t part) {
     if (part > 4)goto fail;
     if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) goto fail;
     part_t* p = &cacheBuffer_.mbr.part[part - 1];
-    if ((p->boot & 0X7F) != 0  ||
+    if ((p->boot & 0x7F) != 0  ||
         p->totalSectors < 100 ||
         p->firstSector == 0) {
       // not a valid partition
diff --git a/Marlin/SdVolume.h b/Marlin/SdVolume.h
index 990248d6a..3041a6dfb 100644
--- a/Marlin/SdVolume.h
+++ b/Marlin/SdVolume.h
@@ -76,7 +76,7 @@ class SdVolume {
    */
   cache_t* cacheClear() {
     if (!cacheFlush()) return 0;
-    cacheBlockNumber_ = 0XFFFFFFFF;
+    cacheBlockNumber_ = 0xFFFFFFFF;
     return &cacheBuffer_;
   }
   /** Initialize a FAT volume.  Try partition one first then try super
diff --git a/Marlin/pca9632.cpp b/Marlin/pca9632.cpp
index fe0647639..37f7bd7df 100644
--- a/Marlin/pca9632.cpp
+++ b/Marlin/pca9632.cpp
@@ -45,7 +45,7 @@
 #define PCA9632_PWM3        0x05
 #define PCA9632_GRPPWM      0x06
 #define PCA9632_GRPFREQ     0x07
-#define PCA9632_LEDOUT      0X08
+#define PCA9632_LEDOUT      0x08
 #define PCA9632_SUBADR1     0x09
 #define PCA9632_SUBADR2     0x0A
 #define PCA9632_SUBADR3     0x0B
diff --git a/Marlin/softspi.h b/Marlin/softspi.h
index 24ee33fed..3b77e443b 100644
--- a/Marlin/softspi.h
+++ b/Marlin/softspi.h
@@ -455,7 +455,7 @@ void badPinCheck(uint8_t pin) {
 static inline __attribute__((always_inline))
 void fastBitWriteSafe(volatile uint8_t* address, uint8_t bit, bool level) {
   uint8_t oldSREG;
-  if (address > (uint8_t*)0X5F) {
+  if (address > (uint8_t*)0x5F) {
     oldSREG = SREG;
     cli();
   }
@@ -464,7 +464,7 @@ void fastBitWriteSafe(volatile uint8_t* address, uint8_t bit, bool level) {
   } else {
     *address &= ~(1 << bit);
   }
-  if (address > (uint8_t*)0X5F) {
+  if (address > (uint8_t*)0x5F) {
     SREG = oldSREG;
   }
 }
@@ -488,7 +488,7 @@ bool fastDigitalRead(uint8_t pin) {
 static inline __attribute__((always_inline))
 void fastDigitalToggle(uint8_t pin) {
   badPinCheck(pin);
-    if (pinMap[pin].pin > (uint8_t*)0X5F) {
+    if (pinMap[pin].pin > (uint8_t*)0x5F) {
       // must write bit to high address port
       *pinMap[pin].pin = 1 << pinMap[pin].bit;
     } else {