Forum Post: RE: Customer's I2C Question

Hi Sivaraj,

The customer has come back with the following that they were able to get the system working. However there is some issues with the RRDY flag. Please help/advise:

"

All is working okay except I cannot clear the RRDY flag once it is set.

I am invoking multiple calls to the driver and the first call is fine, it polls on (RRDY == 1), but when I try to clear RRDY for future transactions, it won't clear.

My understanding of how RRDY works is as follows:

• RRDY flag is set when the contents of RX FIFO buffer >= FIFO THRSH
• RRDY flag is cleared by writing a 1 to the RRDY bit in I2C_IRQSTATUS_RAW
• RRDY flag will be re-asserted if the contents of RX FIFO buffer >= FIFO THRSH

So, RRDY *should* be cleared with the following sequence:

1. RX THRSH = 2 (I2C_BUF |= (1 << 8))

1. Read both bytes

1. Just in case, I clear Tx and Rx FIFOs (I2C_BUF) |= 0x4040)

1. Clear flag (I2C_IRQSTATUS_RAW &= I2C_IRQSTATUS_RAW_RRDY)

1. Note that I2C_BUFSTAT = 0x8002, so the RX FIFO is empty, therefore RRDY should not be re-asserted (unless I am mistaken)

So, what am I doing wrong, here?  Why can I not clear the RRDY flag?


"