Mike,
What baud rate are you running at? The higher, the more critical the timing
is.
With an oscilloscope, measure the period for a single bit, BR = 1/period
A logic analyzer will not work for this.
Even if you could change some setting, without knowing the period of a
single bit, you would be guessing at the timing.
amf
On Thursday, March 7, 2019 at 8:25:53 PM UTC-6, Mike Brandon wrote:
> While I am likely getting in way over my head, are there any settings that
> can be modified on a BeagleBone black as it relates to the UART oscillator?
> I have seen some reference to the specification of the AM335x regarding:
>
> The UART modules each have a 48MHz clock to generate their timing. They
> can be configured in one of two modes: UART 16x and UART 13x, in which
> that clock is divided by 16 and 13, respectively.
>
> I am still trying to get an application I wrote to communicate with a 3rd
> party controller and grasping at straws at this point.I just can't figure
> out why everything works fine when I go through /ttyUSB0 (using a
> USB-serial adapter), but when I try to utilize the /tty04 UART, I can't
> communicate.
>
> Without drowning this thread with every little thing I have done, I have
> come to the following conclusions:
>
> 1) My application works because I can confirm it's functionality when
> connected via USB-serial adapter
> 2) My UART circuit (have tried with a MAX3232 and a MAX232) works because
> I can open up minicom and do a loopback test successfully. I have also
> communicated from mt BB to a Windows PC at the same baud rate that I am
> attempting to use with my application, so based on the fact that the manual
> communication between BB and PC was successful, I feel confident that my
> UART circuit is ok.
> 3) Currently I have a logic analyzer hooked up and I am looking at the
> data I am transmitting from my BB. The applicatio I use with the analyzer
> decodes the protocol and the data I am seeing from my circuit is the data I
> am expecting to see.
>
> This snapshot is from the USB-serial connection transmission:
>
> [image: usb.JPG]
> This snapshot is from the UART circuit transmission:
>
> [image: uart.JPG]
>
>
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