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lguancho
Joined: 08 Sep 2003
Posts: 5
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| Change I2C Master to I2C Slave On the Fly |
 Posted: Wed Apr 06, 2005 4:40 am |
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Hi,all. I have an application requirement on a PIC18F452 board. This board using a IO pin[defined as #define MASTER_I2C input(PIN_B3)] to determine whether it should be a I2C master or I2C slave.
| Code: |
int1 Check_Mode(Void)
{
if (MASTER_I2C)
{
Master_Flag=TRUE;
#use i2c(master, sda=PIN_C4, scl=PIN_C3,FORCE_HW)
//InitI2C();
}
else
{
Master_Flag=FALSE;
#use i2c(slave, sda=PIN_C4, scl=PIN_C3,address=0x90,FORCE_HW) // Default Base Address
get_i2c_slave_addr(); // return my_slave_addr
SSPADD = my_slave_addr;
InitI2C();
enable_interrupts(int_ssp);
}
return(Master_Flag)
}
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I called the check_mode() in my main code, before the loop. For testing, I enable the board for master mode. I just do a series of I2c_start(), i2cwrite(Data1)
,i2c_write(data2), i2c_stop() inside the while(1) loop.
When I monitor the SDA and SCL line (these lines have 4.7K pullups), the lines stays at all times HIGH!!. No I2C packets on my scope.
When I commented out the check_mode and hardcode the #use i2c statement at the beginning of my code, the hardware works instantly!
Question: Can we really change the #use I2C on the fly, by choice of a Mode Selection PIN? I would really appreciated if someone helps
Warmest Regards
lguancho
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Wed Apr 06, 2005 8:19 am |
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| You can definitely switch between master and slave. Take a look at my code in the Code Library. I didn't use the #use, instead, I set it up manually. |
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lguancho
Joined: 08 Sep 2003
Posts: 5
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| Change I2C Master to I2C Slave on the Fly |
| Posted: Thu Apr 07, 2005 8:03 pm |
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Hi, Mark. Saw your code before. I am going to try it. Thanks
lguancho |
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