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Altera_Forum
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19 years ago

Maximum Baud rate possible with RS-232

Hello, I want to use RS-232 interface for communication. I read the NIOS II processor reference which says one can set the baud rate by selecting the standard preset values (where the maximum s...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
19 years ago

Hi,

Take a look at http://www.opencores.org/projects.cgi/web/uart16550/overview (http://www.opencores.org/projects.cgi/web/uart16550/overview).

This UART includes two 16byte FIFO memories (for Rx/Tx), you will have to make some modifications/optimizations to embed it into your NIOS-II system.

We use this UART (verilog version) to communicate with a SIM/SAM module at >512kbps (the electrical interface is far away from being RS232 compatible).

We also use it to communicate with a PC at 115,2kbps (using a MAX3232 compatible chip as we include two ports in the same connector). 115,2kbps is the higher speed I used (1,5M long 3-wire cable) for testing purposes since it is the highest speed that my PCMCIA can handle. At this speed no errors appeared due to signal degradation (no errors detected in programs, signal quality supervised using a 5GHz digital sampling scope).

Once again, proper PCB layout is the key for high speed comms.