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Adventurer
Adventurer
3,972 Views
Registered: ‎11-09-2016

Uart 4M Baud Rate

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Hi,

I need 4M Baud Uart. I send one character(e.g. 0x19) to Logic analyzer. After 1M baud(e.g. 2M,4M),i get invalid character.

For example;

1M baud : 0x19(valid)

2M baud : 0x39(invalid)

4M baud : 0x8E(invalid)

 

I use standart uart code and derive clock from 125MHz on board osc(zybo board). I use clock IP to convert it to 100MHz. And I divide 25 to get 4MHz(4M baud).

I try all possibilities using slewrate/drive power/cmos-lvttl etc. Unfortunately, i can't read correct data(0x19) at 4M baud rate.

Bit pattern(00011001) very similar, i think there is a timing(rise-fall times) problem, logic analyzer decode wrong.

1M baud

1M_baud.png

4M baud

4M_baud.png

Is it possible to reach 4M baud rates with uart?

Any help would be apprecated.

 

 

 

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1 Solution

Accepted Solutions
Adventurer
Adventurer
6,842 Views
Registered: ‎11-09-2016

Re: Uart 4M Baud Rate

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The problem solved:

Logic analyzer capture values(threshold&hysteresis)before was very low. I tune these values. It decode character correctly now.

Thanks

View solution in original post

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4 Replies
Xilinx Employee
Xilinx Employee
3,939 Views
Registered: ‎08-02-2007

Re: Uart 4M Baud Rate

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hi,

 

the uart IP in the IP catalog can reach upto a maximum of 921,600

 

refer to page 15 of this PG. https://www.xilinx.com/support/documentation/ip_documentation/axi_uartlite/v2_0/pg142-axi-uartlite.pdf

 

--hs

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Adventurer
Adventurer
3,931 Views
Registered: ‎11-09-2016

Re: Uart 4M Baud Rate

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Thanks,

I use custom VHDL coded UART. You can see in figure.

 

 

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Adventurer
Adventurer
6,843 Views
Registered: ‎11-09-2016

Re: Uart 4M Baud Rate

Jump to solution

The problem solved:

Logic analyzer capture values(threshold&hysteresis)before was very low. I tune these values. It decode character correctly now.

Thanks

View solution in original post

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Visitor andrea1984
Visitor
317 Views
Registered: ‎06-03-2019

Re: Uart 4M Baud Rate

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I've the same problem using AXI UART. I saw that you wrote the UART driver. Can you give me the code? I need a 6Mbaud, and I don't know how to do.

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