[SOLVED] No clock signal at sck pin in spi communication

[Pushpkant]

I am trying to send data from one atmega8 to another atmega8 using the spi.
But on the master mpu there is no clock signal at sck pin.

 

[barry]

There must be something wrong.

 

[amit.kumar11]

Hi,

Check in software, SPI initialisation , clock setting and other stuffs.

 

[Pushpkant]

I am using the following code:

---

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
// SPI master to send data to another MCU
 
#include<avr/io.h>
 
#define DDR_SPI DDRB
#define DD_MOSI PB3
#define DD_SCK  PB5
#define DD_SS   PB2
 
void SPI_MasterInit(void)
{
    /* Set MOSI and SCK output and SS as output, all other input */
    DDR_SPI = ( 1 << DD_MOSI) | ( 1 << DD_SCK) | ( 1 << DD_SS);
 
    /* Enable SPI, Master, set clock rate */
    SPCR = ( 1 << SPE) | ( 1 << MSTR) | (1 << SPR0) | (1 << SPR1);
 
    return;
}
 
void SPI_MasterTransmit(char cData)
{
    /* Start Transmission */
    SPDR = cData;
 
    /* Wait for transmission to complete */
    while(~(SPSR & (1 << SPIF)))
    {
    }
 
    return;
}
 
void msdelay(unsigned long itime)
{
    unsigned long i,j;
    
    for(i=0; i< itime; i++)
    {
        for(j=0; j<1000; j++)
        {}
    }
    return;
}
 
 
 
int main()
{
    unsigned int i;
    i=0;
 
    DDRC = 0xFF;
    DDRD = 0xFF;
    
    SPI_MasterInit();
 
    while(1)
    {
        SPI_MasterTransmit(i);
        PORTD = i;
        msdelay(1);
        i++;
    }
    
    return 0;
}

---

- - - Updated - - -

I don't know why the previous code is not running. But this one is OK,
I am getting the clock signal now at SCK Pin.

---

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
// SPI_test 2
 
#include<avr/io.h>
 
void SPI_Init(void)
{
    DDRB |= (1<<2) | (1<<3) | (1<<5);   //SCK, MOSI and SS as output
    DDRB &= ~(1<<4);                    //MISO as input
 
    SPCR |= (1 << MSTR);                //set as master
    SPCR |= (1 << SPR0) | (1 << SPR1);  //set spi clock as fck/128
    SPCR |= (1 << SPE);                 // enable the spi
    
    return;
}
 
 
void SPI_Master_Tx(unsigned char data)
{
    SPDR = data;
 
    while(!(SPSR & (1<<SPIF)))
    {
    }
    
    return;
}
 
void msdelay(unsigned long itime)
{
    unsigned long i,j;
 
    for(i=0; i<itime; i++)
    {
        for(j=0;j<1000; j++)
        {
        }
    }
 
    return;
}
 
int main()
{
    unsigned char i=0;
 
    DDRC = 0xFF;
 
    SPI_Init();
 
    while(1)
    {
        SPI_Master_Tx(i);
        PORTC = 0x55;
        msdelay(10);
        PORTC = 0xAA;
        msdelay(10);
    }
    return 0;
}

---

.