I2C with Flowcode

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manio1
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I2C with Flowcode

Postby manio1 » Wed Nov 30, 2005 2:09 pm

Hi,
Is there any way to interface I2C device like 20c16 with Flowcode?

Ingelsw
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Joined: Mon Dec 05, 2005 11:55 am
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Postby Ingelsw » Mon Dec 05, 2005 12:24 pm

Hi All,

I think this is a question for Ian. I have the same request as Manio. I want to hook up some I2C components (like PCF8574) and i know this should be possible because the webserver E-blocks is using I2C. I suppose that i could go in the C code of the webserver E-block but i'm not such an expert in C. The beauty of flowcode is that in normal case, you don't have to do this...

Is a macro available to use I2C?

Many thanks

Wilbert

Ian
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Postby Ian » Mon Dec 05, 2005 2:35 pm

We don't have a Flowcode component for I2C yet I'm afraid.
We are looking at doing one at some point soon, but with a busy schedule we can't say when.

However I2C comms is possible using C code.
there is a lot of detail on I2C on the Microchip website, and in the PIC datasheets.


Below is a bit of code that is taken from the Interent component, which utilizes I2C, that you can use as a basis for some custom code.
I haven't tried it however, and it will no doubt need a bit of tweaking for use in Flowcode, but it might help you out with your own experimentation.


//common implementations
char MaskFromBit(char bit)
{
char retVal = 0;
switch (bit)
{
case 0:
retVal = 0x01;
break;

case 1:
retVal = 0x02;
break;

case 2:
retVal = 0x04;
break;

case 3:
retVal = 0x08;
break;

case 4:
retVal = 0x10;
break;

case 5:
retVal = 0x20;
break;

case 6:
retVal = 0x40;
break;

case 7:
retVal = 0x80;
break;
}
return (retVal);
}

char ReadI2CByte(char lastbyte)
{
char retVal = 0;
char mask;

#ifndef MX_MI2C
asm error "Chip does not have master I2C capability"
#endif

//wait until the bus is idle...
mask = MaskFromBit(R_W);
while (sspstat & mask); // tx in progress?

mask = MaskFromBit(ACKEN);
mask = mask | MaskFromBit(RCEN);
mask = mask | MaskFromBit(PEN);
mask = mask | MaskFromBit(RSEN);
mask = mask | MaskFromBit(SEN);
while (sspcon2 & mask); // bus busy?

//set RCEN and wait for it to clear
mask = MaskFromBit(RCEN);
sspcon2 |= mask;
while ((sspcon2 & mask) == mask);

if (lastbyte == 0)
{
clear_bit(sspcon2, ACKDT);
} else {
set_bit(sspcon2, ACKDT);
}

//set ACKEN and wait for it to clear
mask = MaskFromBit(ACKEN);
sspcon2 |= mask;
while ((sspcon2 & mask) == mask);

retVal = sspbuf;

return (retVal);
}


void SendI2CByte(char val)
{

char rw_mask = MaskFromBit(R_W);
char mask;

#ifndef MX_MI2C
asm error "Chip does not have master I2C capability"
#endif

//wait until the bus is idle...
while (sspstat & rw_mask); // tx in progress?

mask = MaskFromBit(ACKEN);
mask = mask | MaskFromBit(RCEN);
mask = mask | MaskFromBit(PEN);
mask = mask | MaskFromBit(RSEN);
mask = mask | MaskFromBit(SEN);
while (sspcon2 & mask); // bus busy?

mask = MaskFromBit(BF);
while (sspstat & mask); // buffer still full?

sspbuf = val;

while (sspstat & rw_mask); // tx in progress?

//mask = MaskFromBit(ACKSTAT);
//while (sspcon2 & mask); // ack?

return;
}


void MAC_SendI2CStart()
{

#ifndef MX_MI2C
asm error "Chip does not have master I2C capability"
#endif

//set SEN and wait for it to clear
char mask = MaskFromBit(SEN);
sspcon2 |= mask;
while ((sspcon2 & mask) == mask);

return;
}


void MAC_SendI2CStop()
{

#ifndef MX_MI2C
asm error "Chip does not have master I2C capability"
#endif

//set PEN and wait for it to clear
char mask = MaskFromBit(PEN);
sspcon2 |= mask;
while ((sspcon2 & mask) == mask);

return;
}

Ingelsw
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Postby Ingelsw » Mon Dec 05, 2005 9:25 pm

Hi Ian,

Thanks a lot for your response and help. I will give it a try this weekend (i'm not sure with my knowledge of C that it will work).
I hope the I2C component will be available soon!!

Best regards

Wilbert

manio1
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Postby manio1 » Tue Dec 06, 2005 9:21 am

Thanks Ian,
I have no clue programing in C, but hopefuly with some reading i'll be able to understand your example.

jimhumphries
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Postby jimhumphries » Tue Jan 10, 2006 8:00 am

I too can use an I2C module. Could this be made "peripheral independent" so that any available pin/part can be used? Would I2C components be available for "generic" EEPROM, "generic" DAC, "genaric" clock, etc.?

Jim