5 years, 5 months ago.

SPI connection for FLASH MEMORY

Hi all!

I wanted to ask questions regarding SPI for a flash memory device. I have attached the code below.

What am I working with: Discovery Board STM32F407VG Offline MBED CLI compiler using GCC ARM toolchain SPI device: SST25VF NOR Flash Memory device (with 2MB storage)

What I have done: I have successfully read the whoami data from this flash memory, and i got a read back which is correct. However, when I wanted to store and read back the data, it is just messed up. You can see the results below:

register = 0xBF 0x25 0x41 
what to save is: 2

 result = 255 

I am stuck on how to have the result shown correctly! Actually I wanted to save some results from analog in, but now I'm trying with this int data first (which I am still stuck)

My whole code for this is shown below:

#include "mbed.h"
#include "SWO.h"

SPI spi(PA_7, PA_6, PA_5); // mosi, miso, sclk
DigitalOut cs(PB_6);
SWO_Channel swo("channel");
Serial ardu(PA_2, PA_3); //tx rx

#define JEDEC_ID	0x9F //device ID
#define READ_N		0x03 //read bit
#define	FULLERASE	0x60 //full chip erase
#define AAIWRITE	0xAD //auto address increment
#define WREN		0x06 //Write Enable! should be init first!
#define WRDI		0x04 //write disble
#define PROG_1dat	0x02 //write 1 data byte (8bits)


//initialization voids!

void flash_on(){ //enable chip
	cs = 0;
}

void flash_off(){ //disable chip
	cs = 1;
}

void flash_init() { //init of chip
	spi.frequency(12000000);
	spi.format(8,3); //this means: 8 bits for each command, and use 3rd spimode
	flash_off();
}

void flash_test(){
	flash_on();
	spi.write(JEDEC_ID);
	int whoami = spi.write(0);
	int whoami2 = spi.write(0);
	int whoami3 = spi.write(0);
	ardu.printf("register = 0x%X 0x%X 0x%X \n", whoami, whoami2, whoami3);
	flash_off();
}

void write_en(){
	flash_on();
	spi.write(WREN);
	flash_off();
}

//main program!
int main(){
	flash_init();
	
	//testing flash condition
	flash_test();

	//Writing data!
	//1st: WREN should be executed first!
	write_en(); //write enable first!

	flash_on();
	spi.write(FULLERASE);
	wait(0.5);
	flash_off();

	write_en();

	flash_on();
	spi.write(PROG_1dat);
	spi.write(0x00);

	int testings = 2;

	swo.printf("what to save is: %d \n", testings);

	spi.write(testings);
	wait(0.1);
	flash_off();


	// Reading Data!
	wait(1);
	write_en();

	flash_on();
	spi.write(READ_N);
	spi.write(0x00);



	char result = spi.write(0);

	flash_off();
	swo.printf("\n result = %d \n", result);

}

I am assuming the mistake should be somewhere in the data type or the size of the data etc. Buuut, I am now clueless and I am really stuck on how to get this device to read and write. Can anyone help me with this issue? I would be really grateful for any kind of help!

Thank you! Stanley