[Teensy 3.2] SD card breakout sometimes does not initialise (SPI connection)

D

daanv

Member
Hello everyone,

I am cross posting this question from Arduino Stackexchange because I'm realising that this particular issue might be more Teensy related.

I have connected this Adafruit SD Breakout to a Teensy 3.2 over SPI. Because Teensy 3.2 is 3.3 V, I've connected the 3.3 V pin of the Teensy to the 3V pin of the SD breakout.

See sketch below. I'm using Arduino IDE 2.0.4. The SD card is a micro SD HC 32 GB, see photos. FAT32. The Teensy SD library is used (not the Arduino standard one). The SD setup usually goes fine, but every now and then it fails. Whenever the setup goes fine, writing data to the SD card thereafter also goes fine. Does anyone know what this failing could be caused by? Perhaps the SD card is a bit flaky? Or something in software (library)?

My initial guess would be with the wiring, but I've seen similar problems on a PCB with a SD module on it. Hence I think there's more at play than just wiring.

N.B. on the photo you can see there is also an ADXL breakout board connected. However that is over I2C and does not participate in this setup. I've left it in there because I don't want to have to take it out and reconnect it later.

UPDATE: Someone asked me what happened if I removed and reinserted the SD card whilst the sketch is stuck in the "SD initialization failed" while loop. The answer is: It depends. Once when I did it, the setup completed fine and the SD card was functional after that. Another time it just continued in the "SD initialization failed" loop. And then another time still, the setup completed fine but then the error popped up "error opening datalog.txt". I have been noticing a pattern where whenever I get the "error opening datalog.txt" error, on subsequent resets the "SD initialization failed" error is more prevalent.


Code: 
/*
  SD card datalogger

  This example shows how to log data from three analog sensors
  to an SD card using the SD library. Pin numbers reflect the default
  SPI pins for Uno and Nano models

  The circuit:
   analog sensors on analog pins 0, 1, and 2
   SD card attached to SPI bus as follows:
 ** SDO - pin 11
 ** SDI - pin 12
 ** CLK - pin 13
 ** CS - depends on your SD card shield or module.
        Pin 10 used here for consistency with other Arduino examples
    (for MKR Zero SD: SDCARD_SS_PIN)

  created  24 Nov 2010
  modified  24 July 2020
  by Tom Igoe

  This example code is in the public domain.

*/

#include <SPI.h>
#include <SD.h>

const int chipSelect = 10;
#define LED_PIN 7

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  // wait for Serial Monitor to connect. Needed for native USB port boards only:

  pinMode(LED_PIN, OUTPUT); 
  Serial.print("Initializing SD card...");

  while(!SD.begin(chipSelect)) {
    Serial.println("SD initialization failed.");
    delay(100); 
    digitalWrite(LED_PIN, HIGH);
    delay(50); 
    digitalWrite(LED_PIN, LOW);
    delay(50); 
    digitalWrite(LED_PIN, HIGH);
  }

  Serial.println("initialization done.");
  digitalWrite(LED_PIN, HIGH); 
}

void loop() {
  // make a string for assembling the data to log:
  String dataString = "";

  // read three sensors and append to the string:
  for (int analogPin = 0; analogPin < 3; analogPin++) {
    int sensor = analogRead(analogPin);
    dataString += String(sensor);
    if (analogPin < 2) {
      dataString += ",";
    }
  }

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  File dataFile = SD.open("datalog.txt", FILE_WRITE);

  // if the file is available, write to it:
  if (dataFile) {
    dataFile.println(dataString);
    dataFile.close();
    // print to the serial port too:
    // Serial.println(dataString);
  }
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening datalog.txt");
  }
}

output:
Code: 
09:09:03.970 -> Initializing SD card...initialization done.
09:09:19.976 -> Initializing SD card...initialization done.
09:09:28.293 -> Initializing SD card...initialization done.
09:09:38.538 -> Initializing SD card...SD initialization failed.
09:09:42.748 -> SD initialization failed.
09:09:44.924 -> SD initialization failed.
09:09:47.140 -> SD initialization failed.
09:09:49.346 -> SD initialization failed.
09:09:51.556 -> SD initialization failed.
09:09:53.770 -> SD initialization failed.
09:09:55.939 -> SD initialization failed.
09:09:58.147 -> SD initialization failed.
09:10:00.352 -> SD initialization failed.
09:10:02.518 -> SD initialization failed.
09:10:04.725 -> SD initialization failed.
09:10:06.965 -> SD initialization failed.
09:10:09.160 -> SD initialization failed.
09:10:11.353 -> SD initialization failed.
09:10:13.566 -> SD initialization failed.
09:10:15.775 -> SD initialization failed.
09:10:17.954 -> SD initialization failed.
09:10:20.169 -> SD initialization failed.
09:10:22.368 -> SD initialization failed.
09:10:24.574 -> SD initialization failed.
09:10:26.777 -> SD initialization failed.
09:10:28.979 -> SD initialization failed.
09:10:31.159 -> SD initialization failed.
09:10:33.376 -> SD initialization failed.
09:10:35.565 -> SD initialization failed.
09:10:37.783 -> SD initialization failed.
09:10:39.978 -> SD initialization failed.
09:10:42.166 -> SD initialization failed.
09:10:44.384 -> SD initialization failed.
09:10:46.573 -> SD initialization failed.
09:10:48.793 -> SD initialization failed.
09:10:50.974 -> SD initialization failed.
09:11:51.284 -> Initializing SD card...initialization done.
09:12:18.656 -> Initializing SD card...initialization done.
09:12:28.948 -> Initializing SD card...initialization done.
09:12:32.867 -> Initializing SD card...initialization done.
09:12:38.416 -> Initializing SD card...initialization done.
09:12:44.657 -> Initializing SD card...initialization done.
09:12:52.141 -> Initializing SD card...initialization done.
09:13:08.003 -> Initializing SD card...initialization done.
09:13:10.421 -> Initializing SD card...initialization done.
09:13:12.893 -> Initializing SD card...initialization done.
09:13:15.070 -> Initializing SD card...initialization done.
09:13:17.771 -> Initializing SD card...initialization done.
09:13:19.922 -> Initializing SD card...initialization done.
09:13:25.418 -> Initializing SD card...initialization done.
09:13:28.104 -> Initializing SD card...initialization done.
09:13:30.835 -> Initializing SD card...initialization done.
09:13:33.217 -> Initializing SD card...initialization done.
09:13:36.146 -> Initializing SD card...initialization done.
09:13:40.727 -> Initializing SD card...initialization done.
09:13:44.985 -> Initializing SD card...initialization done.
09:13:49.089 -> Initializing SD card...initialization done.
09:13:51.687 -> Initializing SD card...initialization done.
09:13:55.698 -> Initializing SD card...initialization done.
09:14:00.868 -> Initializing SD card...initialization done.
09:14:03.965 -> Initializing SD card...initialization done.
09:14:06.697 -> Initializing SD card...initialization done.
09:14:10.518 -> Initializing SD card...initialization done.
09:14:13.549 -> Initializing SD card...initialization done.
09:14:18.414 -> Initializing SD card...initialization done.
09:14:22.145 -> Initializing SD card...Initializing SD card...initialization done.
09:14:31.614 -> Initializing SD card...initialization done.
09:14:34.230 -> Initializing SD card...initialization done.
09:14:37.077 -> Initializing SD card...SD initialization failed.
09:14:41.273 -> SD initialization failed.
09:14:43.482 -> SD initialization failed.
09:14:45.675 -> SD initialization failed.
09:14:47.858 -> SD initialization failed.
09:14:50.080 -> SD initialization failed.
09:14:52.286 -> SD initialization failed.
09:14:54.464 -> SD initialization failed.
09:14:56.665 -> SD initialization failed.
09:14:58.931 -> SD initialization failed.
09:15:01.088 -> SD initialization failed.
09:15:03.253 -> SD initialization failed.
09:15:05.482 -> SD initialization failed.
09:15:07.696 -> SD initialization failed.
09:15:09.902 -> SD initialization failed.
09:15:12.096 -> SD initialization failed.
09:15:20.904 -> SD initialization failed.
09:15:23.112 -> SD initialization failed.
09:15:25.287 -> SD initialization failed.
09:15:27.494 -> SD initialization failed.
09:15:29.720 -> SD initialization failed.
09:15:30.936 -> Initializing SD card...SD initialization failed.
09:15:35.095 -> SD initialization failed.
09:15:37.304 -> SD initialization failed.
09:15:39.515 -> SD initialization failed.
09:15:41.713 -> SD initialization failed.
09:15:43.899 -> SD initialization failed.
09:15:46.108 -> SD initialization failed.
09:15:48.320 -> SD initialization failed.
09:15:50.502 -> SD initialization failed.
09:15:52.685 -> SD initialization failed.
09:15:54.920 -> SD initialization failed.
09:15:57.887 -> Initializing SD card...SD initialization failed.
09:16:01.902 -> SD initialization failed.
09:16:04.097 -> SD initialization failed.
09:16:06.312 -> SD initialization failed.
09:16:08.518 -> SD initialization failed.
09:16:10.720 -> SD initialization failed.
09:16:12.901 -> SD initialization failed.
09:16:15.125 -> SD initialization failed.
09:16:17.328 -> SD initialization failed.
09:16:19.521 -> SD initialization failed.
09:16:21.734 -> SD initialization failed.
09:16:23.925 -> SD initialization failed.
09:16:26.097 -> SD initialization failed.
09:16:28.332 -> SD initialization failed.
09:16:30.533 -> SD initialization failed.
09:16:32.732 -> SD initialization failed.
09:16:34.917 -> SD initialization failed.

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Wiring is indeed a big issue.
keep in mind SPI uses a clock rate of 16-33 MHz. That is HF radio frequency. So when the clock wire come close to other wires, lot of crosstalk and corruption may happen.
 
You might need a slower SPI clock speed. Wiring could be an issue, but my main concern is the SD breakout board you're using looks like it has a buffer chip. Some of those chips are quite slow. Usually they are tested only with Arduino Uno which has 8 MHz max SPI speed.

This example code shows how to control the speed and other settings.

https://github.com/PaulStoffregen/S...80fc/examples/SdFat_Usage/SdFat_Usage.ino#L45

You can also open it in Arduino by clicking File > Examples > SD > SdFat_Usage
 
ah that makes a lot of sense! I've been using this exact breakout (and SD card) with an Arduino Nano and never had a problem, and then I've also used the Teensy 4.1 with built-in SD (with this SD card) over SDIO and that also never had a problem.

Hence your explanation for this particular configuration seems very plausible. Will try out your suggestion, thank you!
 
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