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Hot!Auto Baud Rate correction error

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Sibi
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2020/06/04 21:35:22 (permalink)
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Auto Baud Rate correction error

Good Morning
 
I am using a PIC32MX575F512H controller interfaced with a SI8900 isolator featuring an auto baud rate correction mode.The problem is once i send a data 0*AA from the controller the isolator must reply 0*55 as an acknowledgement to indicate that the baud rate is now matched but i have been trying for several attempts and still the baud rate have not matched.I have been receiving wrong data from the isolator.I kindly request some support for this  
post edited by Sibi - 2020/06/05 21:32:00
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du00000001
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Re: Auto Baud Rate correction error 2020/06/05 10:03:57 (permalink)
+1 (1)
Let me guess: you either didn't read or didn't understand SiLabs' AN635 about the autobaud feature.
I don't know how many 0xAA are required (I expect this to depend on your baudrate), but it is made clear thatyou have to transmit a series of 0xAA - until you receive 2 consecutive 0x55.
Example code is give in the AN, but (at least for me) it's not clear for which target. (Might be on of SiLabs' 8051 derivatives.) Thus the adaptation is up to you.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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Sibi
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Re: Auto Baud Rate correction error 2020/06/05 21:47:04 (permalink)
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We have given the 0xAA command for a 1000 times but still the reply from the SI8900 is only mismatching.We even tried to send the UART commands manually by using a TTL to UART convertor but still the reply from SI8900 is mismatching.I have given a range of baud rates from 4800 to 460K but still no baud rate match has occurred.I have read and followed all the instructions posted in AN635 and AN637.Finally i also found that if i give baud rate more than 115k the SI8900 sends null as reply whereas for baud rates less than 115k i get mismatched replies.I have attached the data received from SI8900 in my initial post.
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ric
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Re: Auto Baud Rate correction error 2020/06/06 00:46:17 (permalink)
+1 (1)
Sibi
The problem is once i send a data 0*AA from the controller the isolator must reply 0*55 as an acknowledgement to indicate that the baud rate is now matched but i have been trying for several attempts and still the baud rate have not matched.I have been receiving wrong data from the isolator.I kindly request some support for this  

Why are you sending "0*AA" ?
It tells you to just send the raw hex character 0xAA over and over until you received two raw 0x55 characters.
It sounds like you are sending '0', '*', 'A', 'A' ASCII characters, which is never going to work.
 

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Sibi
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Re: Auto Baud Rate correction error 2020/06/06 02:33:13 (permalink)
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No i didn't send my data as '0','*','A','A' but rather the hexadecimal value 0xAA only if u can see my document attached in the 1st post u can see the data that i got from the SI8900 isolator.
 
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du00000001
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Re: Auto Baud Rate correction error 2020/06/06 02:43:24 (permalink)
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OK - might be the time to use a scope.
Start with a shot showing TX, RX and the SI8900's supply voltage. I'd love to see about 5 0xAAs in this image.

PEBKAC / EBKAC / POBCAK / PICNIC (eventually see en.wikipedia.org)
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Sibi
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Re: Auto Baud Rate correction error 2020/06/06 23:13:09 (permalink)
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I am at the time not able to arrange this for u but i have already checked it with a CRO if the pulse is generated from Tx and Rx line and also the supply for SI8900 is measured to be 3.3V with proper ground.We have a given a continous pulse of 0xAA continously for 1000 times and the reply from the Si8900 is 0xAB,0x02 etc and not the required 0x55
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