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] > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/f4230b38-af80-4719-b971-026f242f18bf%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
