ATMEGA8A + SPI memory strange behavior
I've bought SPI memory MX25L8006EPI and now I try to connect it to ATMEGA8A to test it. The schematic is very simple and doesn't change from others over the internet:
ATMEGA8A works at 8Mz internal oscillator, 3.3V. The fuses are HIGH: 0xD1, LOW: 0xE4.
I use Atmel Studio 7 for coding and AVRISP mkII to programming the uC. Since EEPROM needs 3.3V I've connected 5V 700mA power supply module using LM317 as you can see on the scheme. I don't think it matters but anyway ...
The code is also very simple, I've partly copied that from some page in the Internet:
#define SLAVESELECT (PORTB &= ~(1<<PORTB2))
#define SLAVEDESELECT (PORTB |= (1<<PORTB2))
#define WREN 6
#define WRDI 4
#define RDSR 5
#define WRSR 1
#define READ 3
#define WRITE 2
#define RDID 0x9F
#define byte unsigned char
void SPI_Init()
{
DDRB = (1<<PORTB2)|(1<<PORTB3)|(1<<PORTB5);
SLAVEDESELECT;
//SPSR |= (1<<SPI2X);
SPCR |= (1<<SPE)|(1<<MSTR)|(1 << SPR1);
_delay_ms(10);
}
byte SPI_Transfer(volatile byte data)
{
SPDR = data;
while (!(SPSR & (1<<SPIF)));
return SPDR;
}
void Get_Identification(byte data[3])
{
SLAVESELECT;
SPI_Transfer(RDID);
data[0] = SPI_Transfer(0xFF);
data[1] = SPI_Transfer(0xFF);
data[2] = SPI_Transfer(0xFF);
SLAVEDESELECT;
}
byte GetStatus()
{
byte status;
SLAVESELECT;
SPI_Transfer(RDSR);
status = SPI_Transfer(0xFF);
SLAVEDESELECT;
return status;
}
void SetWriteEnable(short ebable)
{
SLAVESELECT;
SPI_Transfer((ebable != 0) ? WREN : WRDI);
SLAVEDESELECT;
}
void SetStatus(byte status)
{
SetWriteEnable(1);
SLAVESELECT;
SPI_Transfer(WRSR);
SPI_Transfer(status);
SLAVEDESELECT;
_delay_ms(100);
}
int main(void)
{
SPI_Init();
byte status = 0x1C;
DEBUG_PRINT("rnSet status:%drn",status);
SetStatus(status);
status = GetStatus();
DEBUG_PRINT("rnGet status:%drn",status);
byte buffer[3];
Get_Identification(buffer);
DEBUG_PRINT("Byte0:%xrn", buffer[0]);
DEBUG_PRINT("Byte1:%xrn", buffer[1]);
DEBUG_PRINT("Byte2:%xrn", buffer[2]);
while (1)
{
}
}
DEBUG_PRINT is my function to send formatted string throught USART. I use it to print out debug info.
Everything looks fine but when I run that I get some strange behavior. The output is:
Set status:28
Get status:24
Byte0:80
Byte1:0
Byte2:10
Firstly I set status register using WRSR opcode. it should set it to 00011100 but when I read the status using RDSR opcode I get 00011000.
Ok, maybe there is some trouble with status register. Then I try to read ID register using RDID opcode. It should return 3 bytes - 0xC2 0x20 0x14. But insted I get 0x80 0x0 0x10.
It would be understandable if I get no answer or all 0x00 or 0xFF. But here I read some answer, the problem that the response is totally wrong. Even more interesting is that if I connect the EEPROM to Arduino using at least the same code it works without problem.
I feel that the problem is quite small. It looks that maybe some data order wrong or transfer speed or something like that but I can't get it work.
根据此数据表，当BP2：0设置为5,6或7时，所有块都受到保护。也许，当将其设置为7时，内存仅将其设置为6，因为它没有区别。
链接地址: http://www.djcxy.com/p/78612.html上一篇: 浮点和双变量的比较