Use SD Card with the AVR IoT Cellular Mini

[vonrle]

Hello everyone,

I tried to connect a Feather SD Card Device with my AVR IoT Cellular Mini Board and have some issues with it. From the documentation I know, that the Feather CS Pin is the Pxn, but I couldn't find the correct way to call that PIN, as I get an error, when I use "PIN_Pxn" in my code, that PIN_Pxn needs to be defined.

I would be very greatful for your help!

[M65649]

Hello @vonrle,

Could you show some code?

[vonrle]

Sure, I just used the example code of the SD Card library:
`/*
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
** MISO - pin 12
** CLK - pin 13
** CS - pin 4 (for MKRZero SD: SDCARD_SS_PIN)

created 24 Nov 2010
modified 9 Apr 2012
by Tom Igoe

This example code is in the public domain.

*/

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

const int chipSelect = PIN_Pxn;

void setup() {
// Open Serial3 communications and wait for port to open:
Serial3.begin(115200);
while (!Serial3) {
; // wait for Serial3 port to connect. Needed for native USB port only
}

Serial3.print("Initializing SD card...");

// see if the card is present and can be initialized:
if (!SD.begin(chipSelect)) {
Serial3.println("Card failed, or not present");
// don't do anything more:
while (1);
}
Serial3.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 Serial3 port too:
Serial3.println(dataString);
}
// if the file isn't open, pop up an error:
else {
Serial3.println("error opening datalog.txt");
}
}`

And I get the following error: 'PIN_Pxn' was not declared in this scope
which is not there when I try it with any other pin declaration from the documentation, but then it does not find the SD Card

[M65649]

Have you followed this guide: https://learn.adafruit.com/adafruit-adalogger-featherwing/adafruit2-rtc-with-arduino ? The feather is on the I2C 1 bus (see page 7 here: https://ww1.microchip.com/downloads/en/DeviceDoc/AVR-IoT-Cellular-Mini-HW-UserGuide-DS50003320.pdf), so you need to use Wire1 instead of Wire. I had a quick look at the RTCLib, and I believe the begin should be changed to this:

rtc.begin(&Wire1);

[vonrle]

Yes, I followed the guide and it works with a Feather M0 Adalogger, but not with the AVR. I'm not sure, weather it's because of the diffenrent names for the pins for the AVR and the Feather, that the RTClib can not deal with.

[M65649]

See my updated comment above. I believe it is just because we have two I2C buses on the AVR-IoT Cellular Mini.

[vonrle]

Perfect, it works now. Thank you so much!

[M65649]

Superb 😄