Atmel Dataflash

[Kimi]

Hello.. I used some of the codes posted here for driving a 4Mbit dataflash. I can get the Status byte (so the SPI communication is good, and the Dataflash response). But when I tried to write or read the Buffer 1. It seems like it didn't write!

The pieces of code that I will post are the rutine to write and read the buffer (Note: Instead of using a 9bits address for the buffer, I used an 8bits one, and set the 9th to 0).

unsigned int8 ReadByteFromDataFlashBuffer1(unsigned int8 Address)
{
unsigned int8 Data;

DATA_FLASH_CS_LO();
//command
wrSPI(0x54); //BUFFER 1 READ
//don't care 8 bits
wrSPI(0);
//2 high address bits
wrSPI(0);
//8 low address bits
wrSPI(Address);
//don't care 8 bits
wrSPI(0);
Data = rdSPI();
DATA_FLASH_CS_HI();
return (Data);
}


void WriteByteToDataFlashBuffer1(unsigned int8 Address, unsigned int8 Data)
{
DATA_FLASH_CS_LO();
//command
wrSPI(0x84); //BUFFER 1 WRITE
//don't care 8 bits
wrSPI(0);
//2 high address bits
wrSPI(0);
//8 low address bits
wrSPI(Address);
//write data byte
wrSPI(Data);
DATA_FLASH_CS_HI();
}



This is part of the Main.. the part that writes and reads from the buffer 1

for (counter = 0; counter <= 200; counter++){
WriteByteToDataFlashBuffer1(counter,counter+40);
delay_ms(15);
}

delay_ms(1000);

for (counter = 0; counter <= 200; counter++) {
c = ReadByteFromDataFlashBuffer1(counter);
fprintf(PC,"Byte %C ::\n\r",c);
}

the %C caracter printed on the screen is nothing (0). Looking with an Scope, I see that really the Dataflash is "sending" 0. So the write is wrong...

Anybody may give me a hand?
THANKS VERY VERY MUCH

Kimi

[ckielstra]

What does your rdSPI() function look like? Is it using spi_read()?
If your PIC is the SPI master, then you should generate clock pulses by calling read_spi() with a parameter, e.g. read_spi(0).

[Kimi]

void wrSPI(unsigned int8 Shift)
{
unsigned int8 BitCnt = 8;

do
{
output_low(SCK);
delay_ms(2);
if(Shift & 0x80)
output_high(SDO);
else
output_low(SDO);
Shift <<= 1;
output_high(SCK);
delay_ms(2);
} while (--BitCnt);
}


unsigned int8 rdSPI(void)
{
unsigned int8 BitCnt = 8;
unsigned int8 Shift;

do
{
output_low(SCK);
delay_ms(2);
Shift <<= 1;
if(!(input(SDI))) //SDI Input 0
Shift &= ~1;
else
Shift |= 1; //SDI Input 1
output_high(SCK);
delay_ms(2);
} while (--BitCnt);
return(Shift);
}

These are the two rutines that drives the SPI. It's soft SPI in Master Mode.

[Kimi]

I changed my main with this little main...

for (counter = 0; counter <=3; counter++) {
data = ReadDataFlashStatus();
fprintf (PC," %X ",data);
} //Receive 4 sattus bytes... al of them 9C (my dataflash is AT45DB041

while(ReadDataFlashStatus() != 0x9C);
WriteByteToDataFlashBuffer1(1,0x20);
while(ReadDataFlashStatus() != 0x9C);
data = ReadByteFromDataFlashBuffer1(1);
fprintf(PC," %X ",data); //Expected 20, but I see 0

while(ReadDataFlashStatus() != 0x9C);
WriteByteToDataFlashBuffer1(2,0x21);
while(ReadDataFlashStatus() != 0x9C);
data = ReadByteFromDataFlashBuffer1(1);
fprintf(PC," %X ",data); //Expected 21 in HEX, but I see 0

while(ReadDataFlashStatus() != 0x9C);
WriteByteToDataFlashBuffer1(3,0x22);
while(ReadDataFlashStatus() != 0x9C);
data = ReadByteFromDataFlashBuffer1(1);
fprintf(PC," %X ",data); //Expected 22, but I see 0

while(ReadDataFlashStatus() != 0x9C);
WriteByteToDataFlashBuffer1(4,0x23);
while(ReadDataFlashStatus() != 0x9C);
data = ReadByteFromDataFlashBuffer1(1);
fprintf(PC," %X ",data); //Expected 23, but I see 0

What's wrong with this?? asking and reading the Status byte is okey...but I cannot read from the Buffer.. NOTE: Again the scope says that the bytes are going out from the pic, and that the memory sends correctly every byte...

thanks
Kimi

[dvsoft]

good evening

your code seems to be correct, but not very clear

1 Which PIC is which frequency has
2 Which version of the compiler
3 how is to carry out convertion of voltage between PIC 5V and the Dataflash 3.3 V

bus SPI of the dataflash is faster than that of the PIC 10 MHz for a pic18 20Mhz for the dataflash
therefore you do not need to use the function delay_ms() between each bit

You must connect pine 1 of the dataflash for test the state of the dataflash (ready/busy)
before each reading or writing of data

After dataflash (CS = 0) you must await at least 200ns before start the reading writing

before putting CS = 0 you must position the clock signal correctly
reading SCK = 1
writing SCK = 0

I you council of reading the document of the dataflash to have more information

bon courrage
Alain

[Kimi]

Thanks

I didn't know that I have to put the SCK in high or low before setting CS. As the Status Read function is working, the rest fo the code should work okey.
PICC Version is 3.216, the PIC18F877 running at 16Mhz.
I was reading the datasheet at the dataflash consumes 20mA or more when writing...mmm.. perhaps that's too much for the 3 diodes supply that Atmel propose in their datasheet, and that I use.
Thanks! Tomorrow at work.. I will reply to this messege and tell you how it was everything!

Thanks again
Kimi

[ckielstra]

The 18F877 has a hardware SPI unit. Why don't you use it? Much faster, less code and you can use the CCS supplied functions for spi_read and spi_write.

[Kimi]

When trying to use the HArdware SPI I cannot even read the status byte of the dataflash...
Up to now, the software version is working more than the Hardware

[dvsoft]

bonjour

hello,

I had the same problem.
that came from my interface

you must connect

Pin1 (ready/Busy) converter 3.3 to 5V
Pin16 (SO) converter 3.3 to V

Pin2 (RESET) to 3.3 V
Pin3 (WP) to 3.3 V
Pin7 (VCC) to 3.3 V
Pin8 (GND) to GND !!

Pin13 (CS) converter 5 v to 3.3V
Pin14 (SCK) converter 5 v to 3.3V
Pin15 (SI) converter 5 v to 3.3V

SPI setting

[Kimi]

Well.... I have a 74LS245.. me be it's a good option to make the converter. Which IC do you use?. My dataflash doesn't have Ready/busy Pin...

I was thinking about doing this..

(SO) converter 3.3 V to 5 V (mey be a Transistor?, or a buffer?)

(RESET) to 3.3 V
(WP) to 3.3 V
(VCC) to 3.3 V
(GND) to GND !!

(CS) directly to PIC (as the Dataflash has 5V tolerant pins)
(SCK) directly to PIC (as the Dataflash has 5V tolerant pins)
(SI) directly to PIC (as the Dataflash has 5V tolerant pins)

All the schematic I saw, doesn't used converter, because the use the PIC at 3V... but I can't use the PIC at that voltage.

Thanks Very Much.
Kimi

[dvsoft]

re-bonjout

Ok,
i send to your email, ma drawing

Alain