Re: Problems with LPC2888 and I2C

Started by November 23, 2009

I am working on a new design based on LPC2888.

The problem that i am facing is that i am not able to initialize the I2C. Even after i write I2CCLKHI and I2CCLKLO registers, i am not getting anywhere near the I2C baud rate of 400 KHz. I am only getting the clock frequency of 12 MHz.

Can you please help with I2C initialization.

With regards,

We have a new design based upon the LPC2888 (now silicon revision
>We have 2 devices attached to the I2C bus in addition to the LPC2888
>(acting as bus master) one E2ROM and one port expander.
>At irregular intervals the LPC2888 loses arbitration (dispite being
>the only master on the bus). It can appear to happen at any bit
>during a transfer.
>Adding a couple of small value resistors in the I2C data lines from
>the other devices (to determine which is pulling the data line low)
>we've established the LPC2888 is outputting a narrow low pulse on
>the data line, in the middle of a high data bit.
>The narrow pulse appears to be going low with the clock going high
>and lasting 0.5uS. After this the clock and data lines go high, the
>arbitration failed indicator bit in the status register is set and
>the LPC2888 doesn't access the I2c bus anymore.
>Bus speed is 100KHz and the pull-up resistors are 4K7.
>Voltages and timings look OK on the scope.
>Any one seen anything like this before?

An Engineer's Guide to the LPC2100 Series