Can not create file on SD Card in Teensy 4.1

[euamrr]

I have a Teensy4.1
Formatted a FAT32 SD card in windows.
When I run the Teensy SD card example all is fine until the sketch tries to create a file.
It can not.
What can I do to enable file creation by Teensy on my card?

The output I get is:

Initializing SD card...Wiring is correct and a card is present.

Card type: SDHC

Volume type is FAT32

Volume size (Kbytes): 7774208
Volume size (Mbytes): 7592

Files found on the card (name, date and size in bytes):
SYSTEM~1/ 2020-11-22 14:48:06
INDEXE~1 2020-11-22 14:48:08 76
WPSETT~1.DAT 2020-12-01 18:45:30 12
HDATA 2020-11-30 18:52:20 192
SDATA 2020-11-30 18:54:54 444
PDATA 2020-11-28 18:17:00 48
HDATA_M 2020-11-28 18:17:26 0
HDATA_Y 2020-11-28 18:17:30 0
SDATA_M 2020-11-28 18:17:36 0
SDATA_Y 2020-11-28 18:17:42 0
PDATA_M 2020-11-28 18:17:50 0
PDATA_Y 2020-11-28 18:17:54 0
Could not create file

The sketch I am using is:

// include the SD library:
#include <SD.h>
#include <SPI.h>

// set up variables using the SD utility library functions:
Sd2Card card;
SdVolume volume;
SdFile root;

// change this to match your SD shield or module;
// Arduino Ethernet shield: pin 4
// Adafruit SD shields and modules: pin 10
// Sparkfun SD shield: pin 8
// Teensy audio board: pin 10
// Teensy 3.5 & 3.6 & 4.1 on-board: BUILTIN_SDCARD
// Wiz820+SD board: pin 4
// Teensy 2.0: pin 0
// Teensy++ 2.0: pin 20
const int chipSelect = BUILTIN_SDCARD;

void setup()
{
  //UNCOMMENT THESE TWO LINES FOR TEENSY AUDIO BOARD:
  //SPI.setMOSI(7);  // Audio shield has MOSI on pin 7
  //SPI.setSCK(14);  // Audio shield has SCK on pin 14
  
 // Open serial communications and wait for port to open:
  Serial.begin(9600);
   while (!Serial) {
    ; // wait for serial port to connect.
  }


  Serial.print("\nInitializing SD card...");


  // we'll use the initialization code from the utility libraries
  // since we're just testing if the card is working!
  if (!card.init(SPI_HALF_SPEED, chipSelect)) {
    Serial.println("initialization failed. Things to check:");
    Serial.println("* is a card inserted?");
    Serial.println("* is your wiring correct?");
    Serial.println("* did you change the chipSelect pin to match your shield or module?");
    return;
  } else {
   Serial.println("Wiring is correct and a card is present.");
  }

  // print the type of card
  Serial.print("\nCard type: ");
  switch(card.type()) {
    case SD_CARD_TYPE_SD1:
      Serial.println("SD1");
      break;
    case SD_CARD_TYPE_SD2:
      Serial.println("SD2");
      break;
    case SD_CARD_TYPE_SDHC:
      Serial.println("SDHC");
      break;
    default:
      Serial.println("Unknown");
  }

  // Now we will try to open the 'volume'/'partition' - it should be FAT16 or FAT32
  if (!volume.init(card)) {
    Serial.println("Could not find FAT16/FAT32 partition.\nMake sure you've formatted the card");
    return;
  }


  // print the type and size of the first FAT-type volume
  uint32_t volumesize;
  Serial.print("\nVolume type is FAT");
  Serial.println(volume.fatType(), DEC);
  Serial.println();
  
  volumesize = volume.blocksPerCluster();    // clusters are collections of blocks
  volumesize *= volume.clusterCount();       // we'll have a lot of clusters
  if (volumesize < 8388608ul) {
    Serial.print("Volume size (bytes): ");
    Serial.println(volumesize * 512);        // SD card blocks are always 512 bytes
  }
  Serial.print("Volume size (Kbytes): ");
  volumesize /= 2;
  Serial.println(volumesize);
  Serial.print("Volume size (Mbytes): ");
  volumesize /= 1024;
  Serial.println(volumesize);

  
  Serial.println("\nFiles found on the card (name, date and size in bytes): ");
  root.openRoot(volume);
  
  // list all files in the card with date and size
  root.ls(LS_R | LS_DATE | LS_SIZE);
}


void loop(void) {
  File blah = SD.open("XXX",FILE_WRITE);
  if (blah) {
    Serial.print("Successfully created file");
  } else {
    Serial.print("Could not create file");
  }
  blah.println("Yadayada");
  blah.close();
  SD.remove("XXX");
  while(true);
}

Thanks for any help...

[Sandwich]

This is the first thing I would check. Someone else was having the issue they could .begin(), but couldn't .open() anything. Quote from Paul on this thread:

The big caveat is whether you're really using the SD library from Teensyduino. It's in hardware/teensy/avr/libraries/SD. If you turn on verbose info, Arduino tells you the full pathname of every library it used. If you have multiple conflicting versions, it should alert you to the conflict and tell you which one it actually used. You really should use the one Teensyduino installs into hardware/teensy/avr/libraries/SD.

[euamrr]

Dear Sand Wich,

Thanks for the reply.
I am pretty sure that I am using the Teensy version of the SD.h library. I even renamed the bog standard Arduino one so that
it wouldn't get picked up. Yet, it is still not writing to the SD
I tried two different SD cards (one brand new)...

The output of a verbose compile is:

/home/marco/arduino-1.8.13/arduino-builder -dump-prefs -logger=machine -hardware /home/marco/arduino-1.8.13/hardware -hardware /home/marco/Arduino/hardware -tools /home/marco/arduino-1.8.13/tools-builder -tools /home/marco/arduino-1.8.13/hardware/tools/avr -built-in-libraries /home/marco/arduino-1.8.13/libraries -libraries /home/marco/Arduino/libraries -fqbn=teensy:avr:teensy41:usb=serial,speed=600,opt=o2std,keys=en-us -ide-version=10813 -build-path /tmp/arduino_build_606012 -warnings=none -build-cache /tmp/arduino_cache_410159 -verbose /home/marco/Arduino/Teensy41_SD_test/Teensy41_SD_test.ino
/home/marco/arduino-1.8.13/arduino-builder -compile -logger=machine -hardware /home/marco/arduino-1.8.13/hardware -hardware /home/marco/Arduino/hardware -tools /home/marco/arduino-1.8.13/tools-builder -tools /home/marco/arduino-1.8.13/hardware/tools/avr -built-in-libraries /home/marco/arduino-1.8.13/libraries -libraries /home/marco/Arduino/libraries -fqbn=teensy:avr:teensy41:usb=serial,speed=600,opt=o2std,keys=en-us -ide-version=10813 -build-path /tmp/arduino_build_606012 -warnings=none -build-cache /tmp/arduino_cache_410159 -verbose /home/marco/Arduino/Teensy41_SD_test/Teensy41_SD_test.ino
Using board 'teensy41' from platform in folder: /home/marco/arduino-1.8.13/hardware/teensy/avr
Using core 'teensy4' from platform in folder: /home/marco/arduino-1.8.13/hardware/teensy/avr
Detecting libraries used...
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-g++ -E -CC -x c++ -w -g -Wall -ffunction-sections -fdata-sections -nostdlib -std=gnu++14 -fno-exceptions -fpermissive -fno-rtti -fno-threadsafe-statics -felide-constructors -Wno-error=narrowing -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -D__IMXRT1062__ -DTEENSYDUINO=153 -DARDUINO=10813 -DARDUINO_TEENSY41 -DF_CPU=600000000 -DUSB_SERIAL -DLAYOUT_US_ENGLISH -I/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp -o /dev/null -DARDUINO_LIB_DISCOVERY_PHASE
Alternatives for SD.h: [SD@1.2.4 SD@1.2.2]
ResolveLibrary(SD.h)
  -> candidates: [SD@1.2.4 SD@1.2.2]
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-g++ -E -CC -x c++ -w -g -Wall -ffunction-sections -fdata-sections -nostdlib -std=gnu++14 -fno-exceptions -fpermissive -fno-rtti -fno-threadsafe-statics -felide-constructors -Wno-error=narrowing -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -D__IMXRT1062__ -DTEENSYDUINO=153 -DARDUINO=10813 -DARDUINO_TEENSY41 -DF_CPU=600000000 -DUSB_SERIAL -DLAYOUT_US_ENGLISH -I/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp -o /dev/null -DARDUINO_LIB_DISCOVERY_PHASE
Alternatives for SPI.h: [SPI@1.0]
ResolveLibrary(SPI.h)
  -> candidates: [SPI@1.0]
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-g++ -E -CC -x c++ -w -g -Wall -ffunction-sections -fdata-sections -nostdlib -std=gnu++14 -fno-exceptions -fpermissive -fno-rtti -fno-threadsafe-statics -felide-constructors -Wno-error=narrowing -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -D__IMXRT1062__ -DTEENSYDUINO=153 -DARDUINO=10813 -DARDUINO_TEENSY41 -DF_CPU=600000000 -DUSB_SERIAL -DLAYOUT_US_ENGLISH -I/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SPI /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp -o /dev/null -DARDUINO_LIB_DISCOVERY_PHASE
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/File.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/SD.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/cache_t3.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/card_t3.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/dir_t3.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/fat_t3.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/file_t3.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/init_t3.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/utility/NXP_SDHC.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/utility/Sd2Card.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/utility/SdFile.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD/utility/SdVolume.cpp
Using cached library dependencies for file: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SPI/SPI.cpp
Generating function prototypes...
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-g++ -E -CC -x c++ -w -g -Wall -ffunction-sections -fdata-sections -nostdlib -std=gnu++14 -fno-exceptions -fpermissive -fno-rtti -fno-threadsafe-statics -felide-constructors -Wno-error=narrowing -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -D__IMXRT1062__ -DTEENSYDUINO=153 -DARDUINO=10813 -DARDUINO_TEENSY41 -DF_CPU=600000000 -DUSB_SERIAL -DLAYOUT_US_ENGLISH -I/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SPI /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp -o /tmp/arduino_build_606012/preproc/ctags_target_for_gcc_minus_e.cpp -DARDUINO_LIB_DISCOVERY_PHASE
/home/marco/arduino-1.8.13/tools-builder/ctags/5.8-arduino11/ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/arduino_build_606012/preproc/ctags_target_for_gcc_minus_e.cpp
Compiling sketch...
/home/marco/arduino-1.8.13/hardware/teensy/../tools/precompile_helper /home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 /tmp/arduino_build_606012 /home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-g++ -x c++-header -O2 -g -Wall -ffunction-sections -fdata-sections -nostdlib -MMD -std=gnu++14 -fno-exceptions -fpermissive -fno-rtti -fno-threadsafe-statics -felide-constructors -Wno-error=narrowing -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -D__IMXRT1062__ -DTEENSYDUINO=153 -DARDUINO=10813 -DARDUINO_TEENSY41 -DF_CPU=600000000 -DUSB_SERIAL -DLAYOUT_US_ENGLISH -I/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 /tmp/arduino_build_606012/pch/Arduino.h -o /tmp/arduino_build_606012/pch/Arduino.h.gch
Using previously compiled file: /tmp/arduino_build_606012/pch/Arduino.h.gch
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-g++ -c -O2 -g -Wall -ffunction-sections -fdata-sections -nostdlib -MMD -std=gnu++14 -fno-exceptions -fpermissive -fno-rtti -fno-threadsafe-statics -felide-constructors -Wno-error=narrowing -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -D__IMXRT1062__ -DTEENSYDUINO=153 -DARDUINO=10813 -DARDUINO_TEENSY41 -DF_CPU=600000000 -DUSB_SERIAL -DLAYOUT_US_ENGLISH -I/tmp/arduino_build_606012/pch -I/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4 -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD -I/home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SPI /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp -o /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp.o
Compiling libraries...
Compiling library "SD"
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/cache_t3.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/dir_t3.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/init_t3.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/File.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/SD.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/card_t3.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/fat_t3.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/file_t3.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/utility/NXP_SDHC.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/utility/Sd2Card.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/utility/SdVolume.cpp.o
Using previously compiled file: /tmp/arduino_build_606012/libraries/SD/utility/SdFile.cpp.o
Compiling library "SPI"
Using previously compiled file: /tmp/arduino_build_606012/libraries/SPI/SPI.cpp.o
Compiling core...
Using precompiled core: /tmp/arduino_cache_410159/core/core_6c39079b90190c67f8ac0eafcdd6ad78.a
Linking everything together...
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-gcc -O2 -Wl,--gc-sections,--relax -T/home/marco/arduino-1.8.13/hardware/teensy/avr/cores/teensy4/imxrt1062_t41.ld -mthumb -mcpu=cortex-m7 -mfloat-abi=hard -mfpu=fpv5-d16 -o /tmp/arduino_build_606012/Teensy41_SD_test.ino.elf /tmp/arduino_build_606012/sketch/Teensy41_SD_test.ino.cpp.o /tmp/arduino_build_606012/libraries/SD/File.cpp.o /tmp/arduino_build_606012/libraries/SD/SD.cpp.o /tmp/arduino_build_606012/libraries/SD/cache_t3.cpp.o /tmp/arduino_build_606012/libraries/SD/card_t3.cpp.o /tmp/arduino_build_606012/libraries/SD/dir_t3.cpp.o /tmp/arduino_build_606012/libraries/SD/fat_t3.cpp.o /tmp/arduino_build_606012/libraries/SD/file_t3.cpp.o /tmp/arduino_build_606012/libraries/SD/init_t3.cpp.o /tmp/arduino_build_606012/libraries/SD/utility/NXP_SDHC.cpp.o /tmp/arduino_build_606012/libraries/SD/utility/Sd2Card.cpp.o /tmp/arduino_build_606012/libraries/SD/utility/SdFile.cpp.o /tmp/arduino_build_606012/libraries/SD/utility/SdVolume.cpp.o /tmp/arduino_build_606012/libraries/SPI/SPI.cpp.o /tmp/arduino_build_606012/../arduino_cache_410159/core/core_6c39079b90190c67f8ac0eafcdd6ad78.a -L/tmp/arduino_build_606012 -larm_cortexM7lfsp_math -lm -lstdc++
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-objcopy -O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0 /tmp/arduino_build_606012/Teensy41_SD_test.ino.elf /tmp/arduino_build_606012/Teensy41_SD_test.ino.eep
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-objcopy -O ihex -R .eeprom /tmp/arduino_build_606012/Teensy41_SD_test.ino.elf /tmp/arduino_build_606012/Teensy41_SD_test.ino.hex
/home/marco/arduino-1.8.13/hardware/teensy/../tools/stdout_redirect /tmp/arduino_build_606012/Teensy41_SD_test.ino.lst /home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-objdump -d -S -C /tmp/arduino_build_606012/Teensy41_SD_test.ino.elf
/home/marco/arduino-1.8.13/hardware/teensy/../tools/stdout_redirect /tmp/arduino_build_606012/Teensy41_SD_test.ino.sym /home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-objdump -t -C /tmp/arduino_build_606012/Teensy41_SD_test.ino.elf
/home/marco/arduino-1.8.13/hardware/teensy/../tools/teensy_post_compile -file=Teensy41_SD_test.ino -path=/tmp/arduino_build_606012 -tools=/home/marco/arduino-1.8.13/hardware/teensy/../tools/ -board=TEENSY41
Multiple libraries were found for "SD.h"
 Used: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD
 Not used: /home/marco/arduino-1.8.13/libraries/SD
Using library SD at version 1.2.2 in folder: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SD 
Using library SPI at version 1.0 in folder: /home/marco/arduino-1.8.13/hardware/teensy/avr/libraries/SPI 
/home/marco/arduino-1.8.13/hardware/teensy/../tools/arm/bin/arm-none-eabi-size -A /tmp/arduino_build_606012/Teensy41_SD_test.ino.elf
Sketch uses 30656 bytes (0%) of program storage space. Maximum is 8126464 bytes.
Global variables use 45756 bytes (8%) of dynamic memory, leaving 478532 bytes for local variables. Maximum is 524288 bytes.

[PaulStoffregen]

Use SD.begin(chipSelect) to initialize the card. Delete all that other init stuff. Look at any of the SD examples in File > Examples > SD, except for CardInfo.

When you initialize the card this way, you can use those info functions to learn about the card. But the rest of the SD library isn't properly initialized. It leaves the SD library unable to work. You need to use SD.begin(pin) to fully initialize the entire SD library when you want to do anything more than get the card info.

You might also consider using the 1.54-beta5. The SD library has been updated / replaced with SdFat. The same SD functions still work, but it can now use long filenames and larger cards.

[WMXZ]

I would first try a standard example from the SD library that writes and reads from SD e.g. ReadWrite
IMHO you are mixing up different low-level calls
e.g. SD.begin is never called

Edit: Paul was faster

[el_supremo]

I ran into a similar problem except that my code couldn't find a file that I knew to be on the SD card - because Windows Explorer showed that it was there.
I used the listfiles example SD sketch to list the SD directory when it was in the builtin slot on a T4.1 and got this:

Initializing SD card...initialization done.
bomb_44.wav                                       598316
bach_441.wav                                      10091100
alien144.wav                                      23036
drbell44.wav                                      203798
log_161231_leap_second.txt                        327908
wwvb_log_170106_1948-170109_0552.txt              835698
wwvb_raw_170114_2031.txt                          512
wwvb_raw_170114_2040.txt                          512
wwvb_raw_170115_1136.txt                          512
wwvb_raw_170114_1154.txt                          512
wwvb_raw_170115_1312.txt                          512
wwvb_raw_170115_1350.txt                          1024
wwvb_raw_170115_1356_1603.txt                     35328
wwvb_raw_170115_1604.txt                          29696
wwvb_raw_170115_1811-2131.txt                     62464
wwvb_raw_170115_2136-1024.txt                     187392
wwvb_raw_170116_xxxx-2008.txt                     75264
wwvb_raw_170117_0222-2106.txt                     271360
System Volume Information/
  IndexerVolumeGuid                               76
  WPSettings.dat                                  12
Violin_open_D_string_Clngre.wav                   873172
ODClngre.wav                                      436608
SDTEST3.WAV                                       13617358
SDTEST4.WAV                                       17173152
SDTEST1.WAV                                       16787550
SDTEST2.WAV                                       16425698
RECORD_AUDIOBOARD.RAW                             410112
fox_rs.bmp                                        61494
BaboonP.jpg                                       15038
EagleEye.jpg                                      37755
fox_rs.jpg                                        7702
lena20k.jpg                                       19414
Mouse.jpg                                         27808
Mouse480.jpg                                      6609
tiger.jpg                                         47316
arduino.jpg                                       8426
Baboon20.jpg                                      12569
Baboon40.jpg                                      24384
BaboonL.jpg                                       12569
foxrsrot.jpg                                      23886
Baboonrs.jpg                                      31707
tiger_rs.jpg                                      33581
19000112.wav                                      131564
xyz20d.wav                                      124460
foxrsrot.bmp                                      61494
done!

But when I put the card into the slot on an ST7735 TFT LCD with cs on pin 4 I got this:

Initializing SD card...initialization done.
bomb_44.wav                                       598316
bach_441.wav                                      10091100
alien144.wav                                      23036
drbell44.wav                                      203798
log_161231_leap_second.txt                        327908
wwvb_log_170106_1948-170109_0552.txt              835698
wwvb_raw_170114_2031.txt                          512
wwvb_raw_170114_2040.txt                          512
wwvb_raw_170115_1136.txt                          512
wwvb_raw_170114_1154.txt                          512
wwvb_raw_170115_1312.txt                          512
wwvb_raw_170115_1350.txt                          1024
wwvb_raw_170115_1356_1603.txt                     35328
wwvb_raw_170115_1604.txt                          29696
wwvb_raw_170115_1811-2131.txt                     62464
wwvb_raw_170115_2136-1024.txt                     187392
wwvb_raw_170116_xxxx-2008.txt                     75264
wwvb_raw_170117_0222-2106.txt                     271360
System Volume Information/
  IndexerVolumeGuid                               76
  WPSettings.dat                                  12
done!

When the card is in the ST7735 slot, none of the files after WPSettings.dat are visible (my code was trying to open fox_rs.bmp). I "fixed" it by using Windows to copy the files I needed from this bad card onto a different one and now it works.

So, try the listfiles example to look at the card. Maybe there's a "System Volume Information" directory getting in your way.

Pete

[el_supremo]

Your problem isn't related to mine. You appear to be using an older version of the cardinfo example. The latest version has root.openRoot and root.ls commented out.
As Paul has suggested, try Arduino 1.8.13 with Teensyduino 1.54-beta5.

Pete

[euamrr]

Thanks all for the help.

Especially Paul Stoffregen

I have made some progress.

I was hoping to open an SD file for simultaneous reading and writing.
Is that even possible? The documentation seems a bit sketchy on this point, and most
examples first open a file for writing, then reopen it for reading.

It seems that if I open a file with FILE_WRITE, then .available() changes behaviour (as opposed to if I open with FILE_READ).

In the following sketch I have commented one line in the main loop.
Uncommenting it and commenting the one above it results in completely different behaviour. .available() never goes false.
Is this the expected behaviour???

Thanks for any help.

/MR

void setup()
{
//UNCOMMENT THESE TWO LINES FOR TEENSY AUDIO BOARD:
//SPI.setMOSI(7); // Audio shield has MOSI on pin 7
//SPI.setSCK(14); // Audio shield has SCK on pin 14

// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect.
}


Serial.print("\nInitializing SD card...");

SD.begin(chipSelect);
}


void loop(void) {
SD.remove("XXX");
File blah = SD.open("XXX",FILE_WRITE);
if (blah) {
Serial.print("Successfully created file");
} else {
Serial.print("Could not create file");
}
blah.println("Yadayada");
blah.close();
blah = SD.open("XXX",FILE_READ);
// blah = SD.open("XXX",FILE_WRITE);
blah.seek(0);
while(blah.available()) {
char h2f5 = blah.read();
Serial.print(h2f5);
}
while(true);
}