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future
Joined: 14 May 2004
Posts: 330
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| i2c master/slave, 2 pic and an eeprom |
 Posted: Wed Oct 08, 2008 4:01 pm |
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Hi,
I am building a device that has 2 pic and an eeprom in the same i2c bus. The code works until I write to the other device, for example:
Master Pic.
| Code: | #use i2c(MASTER, SDA=PIN_C4, SCL=PIN_C3, FORCE_HW)
int1 i2c_ready (char device) {
int1 ack;
i2c_start(); // If the write command is acknowledged,
ack = i2c_write(device); // then the device is ready.
i2c_stop();
return !ack;
}
// readings from the i2c bus
// S=start
// 60=address
// A=ack
// P=stop
i2c_ready(0x60); // S 60 A P
i2c_ready(0x60); // S 60 A P
i2c_ready(0x60); // S 60 A P
i2c_ready(0x60); // S 60 A P
i2c_ready(0xA0); // S A0 A P
i2c_ready(0xA0); // S A0 A P
i2c_ready(0x60); // S 60 N P
i2c_ready(0xA0); // S A0 A P |
The slave pic works fine until I send something to another address, then it will nak forever.
slave pic:
| Code: | char read_i2c(void);
void i2c_interrupt_handler(void);
void i2c_initialize(void);
void write_i2c(unsigned char transmit_byte);
#INT_SSP
void ssp_interupt () {
i2c_interrupt_handler();
}
#define RX_BUF_LEN 64
#define NODE_ADDR 0x60 /* I2C address of the slave node (avoid addr masking) */
unsigned char slave_buffer[RX_BUF_LEN];
int buffer_index;
int comms_error;
int debug_state;
void i2c_initialize (void) {
debug_state = 0;
/* Set up SSP module for 7-bit */
while (SSPCON2 & 0x1F); // ACKEN RCEN PEN RSEN SEN all must be zero
SSPSTAT = 0x00; /* Clear the SSPSTAT register. */
SSPCON1 = 0x36; /* 0011 0110 */
SSPADD = NODE_ADDR; /* Set the slave's address */
/* init buffers */
buffer_index = 0;
enable_interrupts(INT_SSP); /* Enable MSSP interrupts. */
}
void i2c_interrupt_handler (void) {
unsigned char temp_sspstat;
unsigned char this_byte;
unsigned char tx_byte;
int x;
/* Mask out the unnecessary bits */
temp_sspstat = SSPSTAT & 0x2D; /* 0010 1101 */
switch (temp_sspstat)
{
case 0x09: /* 0000 1001 */ /* Write operation, last byte was an address, buffer is full */
buffer_index = 0; /* Clear the buffer index */
this_byte = read_i2c(); /* Do a dummy read of PIC_SSPBUF */
debug_state = 1;
break;
case 0x29: /* 0010 1001 */ /* Write operation, last byte was data, buffer is full */
this_byte = read_i2c(); /* Get the byte from the SSP */
slave_buffer[buffer_index] = this_byte; /* Put it into the buffer */
buffer_index++; /* Increment the buffer pointer */
debug_state = 2;
break;
case 0x0D: /* 0000 1101 */ /* Read operation; last byte was address, buffer is full */
this_byte = read_i2c(); /* Do a dummy read of PIC_SSPBUF to clear it */
// while(SSPSTATbits.BF);
case 0x0C: /* 0000 1100 */ /* Read operation; last byte was an address, buffer is empty */
buffer_index = 0; /* Clear the buffer index */
tx_byte = slave_buffer[buffer_index]; /* Get byte from the buffer */
write_i2c(tx_byte); /* Write the byte to PIC_SSPBUF */
buffer_index++; /* increment the buffer index */
debug_state = 3;
break;
case 0x2C: /* 0010 1100 */ /* Read operation; last byte was data, buffer is empty */
tx_byte = slave_buffer[buffer_index];
write_i2c(tx_byte); /* Write to PIC_SSPBUF */
buffer_index++; /* increment the buffer index */
debug_state = 4;
break;
case 0x28: /* 0010 1000 */ /* A NACK was received when transmitting data back [to] the master. */
debug_state = 5; /* Slave logic is reset in this case. R_W=0, D_A=1, and BF=0. */
break; /* If we don't stop in this state, then something is wrong!! */
default:
debug_state = 0xE;
break;
}
}
void write_i2c(unsigned char transmit_byte) {
unsigned char write_collision = 1;
while (SSPSTATbits.BF); /* Is BF bit set in PIC_SSPSTAT? */
while (write_collision)
{
/* If not, then do the i2c_write. */
SSPCON1bits.WCOL = 0; /* Clear the WCOL flag */
SSPBUF = transmit_byte;
/* Was there a write collision? */
if (SSPCON1bits.WCOL)
{
/* Yes there was a write collision. */
write_collision = 1;
}
else
{
/* NO, there was no write collision. */
/* The transmission was successful */
write_collision = 0;
}
}
SSPCON1bits.CKP = 1; /* Release the clock. */
}
/* This function returns the byte in SSPBUF */
unsigned char read_i2c(void) {
return SSPBUF;
} |
I can not see what I am doing wrong. Any tips would be welcome.
Thank you. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Oct 08, 2008 4:22 pm |
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1. Post your PICs and your compiler version.
2. Post the #fuses and #use delay() statements for both PICs.
3. Try it without the FORCE_HW on the master. |
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future
Joined: 14 May 2004
Posts: 330
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| Posted: Wed Oct 08, 2008 4:59 pm |
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ok,
two 18f4620 running at 40mhz. compiler version 3.249.
master fuses:
#fuses H4,NOWDT,NOPROTECT,NOLVP
#use delay(clock=40000000)
#use i2c(MASTER, SDA=PIN_C4, SCL=PIN_C3, FORCE_HW)
slave fuses:
#fuses H4,NOWDT,NOPROTECT,NOLVP
#use delay(clock=40000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
the slave pic does not have the #use i2c directive because it does not use the compiler´s library.
Using the software i2c didn´t help. The communication seems to be fine but something at the end of transaction is left in a wrong state. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Oct 08, 2008 5:11 pm |
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1. Slow down your master. Change the H4 to HS, and change the
#use delay() to 10 MHz.
2. Put delays between the master's i2c statements.
If there is a problem where some process in the slave PIC doesn't have
time to finish, these tests will help to show it. |
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MicroManiac
Joined: 21 Aug 2008
Posts: 34
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| Posted: Thu Oct 09, 2008 3:23 am |
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Try using the Force Software because i faced some problems with the Force hardware previously and when i used the force SW it worked fine
_________________
"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."
Albert Einstein |
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