I2C1 and I2C2

[PROMOD]

From the CCS C manual:


I2C1 = Set SDA and SCL to the first module
I2C2 = Set SDA and SCL to the second module

What is first and second module? Someone has told me that some PIC device have two module with SDA and SCL. I2C1 means Set SDA and SCL of DS1307 to first module, with SDA and SCL, of PIC device. If it is so then how will I identify which one is first module?

[temtronic]

The 'module' really means the internal peripheral, in this case, the PIC will have two MSSP (I2C) hardware 'modules'.
If you look at the front page of any PIC datasheet, they will have a section called 'Perpheral Highlights', usually lower right column. They'll briefly describe what 'modules' are in the PIC.
Being really 'old school', I don't think of a PIC having 'modules', I prefer to call them 'peripherals' cause in the beginning PICs didn't have anything like UARTs, MSSPs, etc. Those devices were external to the PICs. Nowadays, they're builtin, on the same die (piece of silicon), around the core of the PIC.

The PIC you're using has 2 hardware I2C modules, so you can separate I2C device into 2 groups, I2C1 and I2C2. The HUGE benefit of 2 HW modules is that once data is sent to the 'module', the PIC can do other things and not have to 'bitbang' the data. You also get interrupt capability, something a SW (SoftWare) module can't easily do.

You could write an entire book about this and I'm guessing someone already has...
Jay

Jay

[PCM programmer]

Look at the 18F46K22 data sheet:
https://ww1.microchip.com/downloads/en/DeviceDoc/40001412G.pdf
Look at this table on page 7:

[Ttelmah]

Many things have 'multiples'. Think about it Port A on the PIC has 'multiple' pins A0, A1, A2 etc.. Which pin is 'A0', and which is 'A1', is identified in the data sheet.

The same is true for peripherals. Chips can have multiple I2C's (some DsPIC's have three), Multiple UART's (up to 5), multiple PWM's etc. etc.. In each case for the base PIC's the pins used are identified in the data sheet. More modern PIC's have the feature 'PPS' (Peripheral Pin Select), where _you_ as a programmer can decide which peripheral connects to which pins. You have to do this before using the peripheral concerned.

In your code, the line:

#USE I2C(I2C1, SLOW=100000, STREAM=DS1307)

Means to setup the hardware I2C1 peripheral, to run at 100KHz, using 'slow' timings for transitions etc., and allow this to be talked to by the name 'DS1307'. Stream names become 'essential', once you use more than one peripheral. Otherwise in your code, remembering 'which' port to use will become hard work.