I am using Debian. I was using terms and the following in my C++ program cfsetispeed(t, B1000000); cfsetospee(t, B1000000);
to set the baud rate. I have downloaded Robert nelsons kernel (based on his wiki) and have found the drivers/tty/serial/omap-serial.c file. However, it appears to have routines to set the 16 versus 13. So I am unclear why the 1MB is so far off. On Monday, June 9, 2014 10:27:58 PM UTC-4, [email protected] wrote: > > What did you do to set the baud rate? There are many ways to set the baud > rate and it is hard to tell if you are using "stty", writing your own > software, or doing something else. It is also unclear which operating > system version you are using. > > Have you found anything helpful in the numerous forum threads related to > UARTs? (see > https://groups.google.com/forum/embed/?place=forum/beagleboard#!categories/beagleboard/uart > ). > > On Monday, June 9, 2014 11:05:59 AM UTC-7, Charles Kerr wrote: >> >> So where do I change this? In the device tree overlay? >> I am just not comfortable on linux. Use to direct control coding a PIC. >> >> >> On Fri, Jun 6, 2014 at 10:25 PM, <[email protected]> wrote: >> >>> I'm unsure how close to the hardware you're working, but it looks like >>> the UART baud rate generator is using 13x oversampling when you were >>> expecting 16x oversampling. This is controlled by MODESELECT field in the >>> UART's MDR1 register. >>> >>> So long as you're using the standard internal clock rates, the UARTs >>> take a 48MHz clock as input, divide that down by the divisor you provide >>> (UART registers DLH and DLL), then use the resulting clock to oversample >>> each pixel period by either 13x or 16x. Since you are trying to get >>> 1Mbaud, a divisor of 3 with 16x oversampling would get you there. It >>> appears as if you have a divisor of 3 with 13x oversampling producing >>> approximately 1.23Mbaud. >>> >>> One small change and you may be good to go. >>> >>> On Friday, June 6, 2014 5:45:39 PM UTC-7, Charles Kerr wrote: >>>> >>>> I setup my serial ports on the BBB to have a 1Mbaud rate. However, >>>> when I look at the output on the logic analyzer, I see the baud rate is >>>> more like 1.214 MBaud. This of course is too much deviation for my >>>> serial >>>> transmission to sync up. I tried setting a custom baud rate, and that >>>> just fails completely. I wanted to use all four uarts. If I need to, I >>>> could bit bang it from the PRU (but then limit myself to two versus four). >>>> Is there a way to setup a more accurate baud rate on the BBB? >>>> >>> -- >>> For more options, visit http://beagleboard.org/discuss >>> --- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "BeagleBoard" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/beagleboard/iFTjCdLNm1Q/unsubscribe. >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- 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]. For more options, visit https://groups.google.com/d/optout.
