Help with FR5969 r/w FRAM

[aegotheles 2]

Sorry to bother if I'm missing something obvious in the documentation - but there's something I can't seem to figure out.

 

I'm migrating a simple datalogger that uses an ATTiny24a, BMP180, and an external EEPROM to (hopefully!) take advantage of the power savings and FRAM on the MSP430FR5969.  I've attached a sample of my code by I can't seem to find anywhere similar functions to EEPROM.read and EEPROM.write.  All I've managed to find is FRAM_write<enter # of bits here> in the fram.c in the DriverLib library.

 

 

/*
Simple code to transmit ID and basic sensor data using OOK
 */
 
#include <EEPROM.h>

int pulse = 50;               //transmit pulse length
int interval = 25;            //interpulse length
int sample = 5000;            //time between sensor sampling
int gap = 500;               //time between transmissions
int idArray[] = {1,0,1,1};    //basic tag ID in binary, e.g. 11 = {1,0,1,1}
int addr = 0;                 //initial EEPROM write address
int address = 0;              //initial EEPROM read address

void setup() {
  Serial.begin(115200);
  // initialize digital pin 13 as an output.
  pinMode(13, OUTPUT);
}

void loop() {
//DATA_COLLECTION AND EEPROM WRITE/READ________________________________________________________________
int sensorData = random(1024);  // this is the BMP180 data but now it's just random junk for testing
  if (addr <= 9){
  EEPROM.write(addr, sensorData);
    addr = addr + 1;
    delay(sample);
  }
  if (addr > 9){
    int sensorTransmit = EEPROM.read(address);
//ID_ARRAY_TRANSMISSION________________________________________________________________________________
      for (int j=0; j<4; j++){
        if (idArray[j] == 1){
          digitalWrite(13, HIGH);   
            delay(pulse);  
        }else{
          digitalWrite(13, LOW);    
            delay(pulse);              
        }
        digitalWrite(13,LOW);
        delay(interval);
      }
//SENSOR_ONE_TRANSMISSION________________________________________________________________________________
      for (int k=0; k<8; k++){
        digitalWrite(13, bitRead(sensorTransmit, k));                 
          delay(pulse);
          digitalWrite(13, LOW);
          delay(interval);
            byte state = bitRead(sensorTransmit,k);
            Serial.print(state);
  }
    Serial.println();
        digitalWrite(13, LOW);  
         delay(gap);
            address = address + 1;
    if (address > 9){
      address = 0;
      addr = 0;
    }
  }
}
 

 

 

Basically all I'm trying to do is log data to the FRAM at a specified interval, then after a certain number of datalogging events read it back out and convert to on-off keying.  Each datalogger has it's own unqiue ID. At a later time I want to look into the different lower power modes on the MSP430, but first things first. 

 

Again, I apologize if I'm overlooking something quite simple. 

[spirilis 1,265]

So I don't recall offhand if Energia provides an "EEPROM" library like Arduino per se, but you will find reading/writing FRAM is actually a little more obvious than you think. The practice is to define an array of bytes but declare it with __attribute__((section(".text"))) so that the compiler & linker stuffs it in the same segment of memory (FRAM) as the rest of the code. Then you don't use read or write calls to hit it- you just literally access the array like you would any array you've declared in RAM.

 

The magic is that its contents retain all changes across resets, unlike a true RAM array. It will get erased if you reflash the sketch or flash a new sketch though.

 

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[aegotheles 2]

Thanks so much for the help. 

 

Just to avoid possible confusion I'm not intending on using an EEPROM, that was just old code from the Arduino and ATTiny24 setup.

 

So I have a few more questions.  1) Do I need to specify an absolute address in with_attribute_((section(".text"))) for it know where to place the 16 bit integer from each reading from the sensor, 2) does it need have a address specified each time in the loop when it adds sensor data and 3) do I need to preallocate the total number of samples? 

[spirilis 1,265]

#1 and #2 no, although I recommend using the native datatype of the info e.g. "int16_t" or "uint16_t" for signed or unsigned 16-bit integers respectively. For #3 - yes. That will be the array size, e.g. the number in brackets, like:

 

__attribute__((section(".text"))) uint16_t SampleStore[256]; // FRAM storage space for 256 16-bit samples

 

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[spirilis 1,265]

Actually for #2, it does not need a "physical address" but what it DOES need is an array subscript, e.g.:

 

SampleStore[15] = data;

 

How you store the current # of samples is a good question. Another FRAM variable could be used:

 

__attribute__((section(".text"))) int SampleCount = 0; // Current # of samples stored in SampleStore, initialized as 0 on first flashing

 

Then you would store samples with:

 

SampleStore[sampleCount++] = data;

 

And each run of that statement stores data in a unique location, and "SampleCount" increments likewise, surviving across resets.

 

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[spirilis 1,265]

Also to be clear, those FRAM variables or arrays should be declared in the global context, i.e. outside of any function.

 

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[spirilis 1,265]

Lastly, check out this thread: http://forum.43oh.com/topic/5474-energia-and-wolverine-tips/

 

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[aegotheles 2]

Great!  Thanks again for all the info.  I'll read this over and hopefully post a working example tomorrow. 

[aegotheles 2]

It worked!  Now to tackle the BMP180.