Teensy 4.0

PIN assignment

Teensyduino IDE installation

• Download & Extract Arduino
• Install udev Rules
  • The udev rule file gives non-root users permission to use the Teensy devices (serial, HID, etc). More Linux tips below.

sudo cp 49-teensy.rules /etc/udev/rules.d/

Upload binary standalone

• teensy_loader_cli -mmcu=imxrt1062 -w evkmimxrt1060_freertos_hello_teensy.hex -v

SPI Timing

• CS_OFF around 40 ns

• SPI CLK in 16M

• Sampling rate evaluation
  • CS_ON+CS_OFF around 1.46 us
  • For 32 Ch in 16M SPI_CLK, the sampling rate for each channel would be:
    • (1000000/1.46*32)/1000=21.4KS

SDIO 4 bit

• Format SD before running
• Change pin define in code
  • SD.begin(BUILTIN_SDCARD)

/*
  SD card datalogger
 
 This example shows how to log data from three analog sensors 
 to an SD card using the SD library.
 	
 The circuit:
 * analog sensors on analog ins 0, 1, and 2
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11, pin 7 on Teensy with audio board
 ** MISO - pin 12
 ** CLK - pin 13, pin 14 on Teensy with audio board
 ** CS - pin 4,  pin 10 on Teensy with audio board
 
 created  24 Nov 2010
 modified 9 Apr 2012
 by Tom Igoe
 
 This example code is in the public domain.
 	 
 */

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

// On the Ethernet Shield, CS is pin 4. Note that even if it's not
// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
// 53 on the Mega) must be left as an output or the SD library
// functions will not work.

// 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 on-board: BUILTIN_SDCARD
// Wiz820+SD board: pin 4
// Teensy 2.0: pin 0
// Teensy++ 2.0: pin 20
//const int chipSelect = 36;

void setup()
{
  //UNCOMMENT THESE TWO LINES FOR TEENSY AUDIO BOARD:
  //SPI.setMOSI(37);  // Audio shield has MOSI on pin 7
  //SPI.setSCK(36);  // 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. Needed for Leonardo only
  }


  Serial.print("Initializing SD card...");
  
  // see if the card is present and can be initialized:
  if (!SD.begin(BUILTIN_SDCARD)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    return;
  }
  Serial.println("card initialized.");
}

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");
  } 
}