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Visitor cannadya1
Visitor
277 Views
Registered: ‎05-18-2018

Question regarding axi_UART FIFO and register addressing

Hello, I just had a few quick questions. 

 

When a "character" is stored in the axi_uartlite FIFO, is this character stored as an unsigned integer? In our case it's a 8-bit message, so is each character stored as a value from 0 to 255? 

 

If within this character, there is a parity bit error, would this message still get transmitted/received?

 

In regards to address,

 

The uart is given a base address automatically within vivado. In my case, 0x42C0_0000 to 0x42C0_FFFF. Would each Tx and Tx message be stored in this range by some offset? 

 

Is the offset different for each message, or is it a standard offset? 

 

Does this relate to FIFO memory at all? 

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3 Replies
Scholar jmcclusk
Scholar
267 Views
Registered: ‎02-24-2014

Re: Question regarding axi_UART FIFO and register addressing

It's all explained here:

 

https://www.xilinx.com/support/documentation/ip_documentation/axi_uartlite/v2_0/pg142-axi-uartlite.pdf

 

You can't randomly access the TX or RX messages, only write or read them sequentially, one byte at at time.   From what I can tell, a parity error on reception sets a flag (or can generate an interrupt), but it's not saved in the RX Fifo.

Don't forget to close a thread when possible by accepting a post as a solution.
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Visitor cannadya1
Visitor
211 Views
Registered: ‎05-18-2018

Re: Question regarding axi_UART FIFO and register addressing

Hi, thanks for the response!

Quick question, when you say "but it's not saved in the RX FIFO" do you mean the flag/interrupt is not saved in the RC FIFO, or that the message is not saved?
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Scholar jmcclusk
Scholar
195 Views
Registered: ‎02-24-2014

Re: Question regarding axi_UART FIFO and register addressing

A parity error generates a status bit, but you can't tell which character actually had the parity error.   The fifo only holds 8 bits of data, and nothing about parity errors.

Don't forget to close a thread when possible by accepting a post as a solution.
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