I am facing a strange interrupt loop on a TL16C550DPFB
reading the IIR we get 0xC4, reading the LSR we get 0x60 repeatedly , this put our driver in an endless loop
the logic of our driver is while there is IRR&1 !=0 , if IRR&0xf=4 -> while LSR&1 read fifo
This cause an endless loop.
Do you know any reason why we could end up at this state? IRR=0xc4, LSR=0x60?
Thanks and best regards
What receiver trigger level do you have set in the FIFO control register, FCR[7:6]?
Does this happen on more than one system?
Are you meeting the timing requirements for reading the RX FIFO? The minimum time between reading the RX FIFO and reading the status registers (IIR and LSR) is 425 ns.
Do you see the actual interrupt pin go high when the IIR is reading 0xC4?
Can you provide more of the interrupt handling routine? You can post it here in the forum or send it directly to my email, firstname.lastname@example.org.
From the code logic you provided above I see no obvious reason that LSR would continually read 0x60 in this situation unless the data is read out of RX FIFO before reading the LSR status register in the interrupt routine.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.