FreeCore Function #6:
I2C Controller Reference Design
Module name: I2C_test
Current release: version 3.0, January 30, 1998
Contributed by: Rune Baeverrud

Changes since version 2.0

• Updated to reflect changes in div_by_n module.

Changes since version 1.0

• Updated to reflect changes in I2C Controller core design - the asynchronous reset input has been added.

Description

Shown below is a sample schematic using the I2C controller.

The above schematic is suitable for interfacing to a 16 bit microprocessor. A few notes on the circuit:

• system clock is 60MHz, div_by_n_DIVISOR=10 => 10MHz clock enable
• I2C_clk_en = 10MHz => I2C_DIVISOR = 10MHz / 400kHz = 25.
• b[] must be valid when WE (Write Enable) goes high
• /IRQ is suitable for a processor with falling edge sensitive interrupt
• polling operation is possible
• remember to add external pull-ups on the SDA and SCL lines!

If you need 8-bit (or lower) operation, it should be an easy task to modify the circuit. You need to add some registers on the input, and some multiplexers at the output, with some address decoding logic. I will leave that part to you now!

Last updated 28 Jul 1999 07:23