I2C Clk and Data lines

[jspencer]

Just want to make sure that my thinking is correct that once the clock and data lines are defined there is no way to swap them. Our product depends on the user to make contact with the correct orientation and sometimes they use it upside down and so the clock and data lines are reversed. Just want to make sure that there is no way to get around this in firmware by swapping the lines.

I tried a small test and it did not work.

[PCM programmer]

It's certainly possible, but you can't change the pins used by the
CCS library code at runtime. The code isn't written to do that.
You would have to create two instances of the device driver.
Each instance would be compiled to use the specified pins.

Also, you would have to rename the functions in the 2nd instance
of the device driver, so they wouldn't conflict with the 1st instance.
For example, let's take the CCS 24256.C eeprom driver.
It has these three functions:

init_ext_eeprom()
read_ext_eeprom()
write_ext_eeprom()

You could make a copy of the 24256.C file, and rename as
24256_swapped.c, or some other appropriate name. Then
within that file, rename all the functions and put in a #use i2c()
statement with the swapped pins.

Example:
#use i2c(master, sda=I2C_SCL, scl=I2C_SDA, fast)
init_ext_eeprom_swapped()
read_ext_eeprom_swapped()
write_ext_eeprom_swapped()

The "normal" (non-swapped) 24256.C file would look like this:
#use i2c(master, sda=I2C_SDA, scl=I2C_SCL, fast)
init_ext_eeprom()
read_ext_eeprom()
write_ext_eeprom()

In your main program, you would determine which driver to use
(normal or swapped), and then set a global flag to indicate this.
Then whenever you want to call the driver, you would check that
flag and call the appropriate routine. Example:

[jspencer]

Thanks PCM. That makes sense now. I've got the code space to add it in, so I'll give it a shot. If I have any questions I'll hollar. It would be a lot easier if the user would just RTFM! Reading the manual would solve a lot of problems.

jspencer

[jspencer]

Thanks again PCM. That worked like a champ!