Hmm, ok, so I'm using the EMBest Baseboard with my STM32F4-Discovery, this
connects PC6 and PC7 to the SP3232EEY-L chip directly, no pull down on Tx.
Interestingly I get junk on them with I upload a file with the BlackMagic
probe.
>From the data sheet the alternate functions on these pins are:
AF2 AF3 AF5 AF6 AF7 AF12 AF13
PC6 TIM3_CH1 TIM8_CH1 I2S2_MCK --- USART6_TX SDIO_D6 DCMI_D0 EVENTOUT
PC7 TIM3_CH2 TIM8_CH2 -- I2S3_MCK USART6_RX SDIO_D7 DCMI_D1 EVENTOUT
Nothing particularly illuminating there (the BMP is using SWD which should
only be wiggling the PA13/14 pins)
I will try swapping to a different USART and see if the problem reproduces
there, Once everything is up and running the port seems to work reliably,
so I can work around it by sending a sync string out and not having the
other end 'trust' the data until the sync string is seen but that is a
hack.
And another interesting bit of debug data, so if I break on bb_setup (my
code to set up stuff :-) Which is this:
void
bb_setup(int32_t baud) {
clock_setup();
systick_setup();
gpio_setup();
usart_setup(baud);
}
And I step through with GDB (stepping over the functions) I get this:
Breakpoint 1, bb_setup (baud=baud@entry=115200) at util.c:139
139 bb_setup(int32_t baud) {
(gdb) next
140 clock_setup();
(gdb) next
139 bb_setup(int32_t baud) {
(gdb) next
140 clock_setup();
(gdb) next
142 gpio_setup();
(gdb) next
140 clock_setup();
(gdb) next
141 systick_setup();
(gdb) next
142 gpio_setup();
(gdb) next
143 usart_setup(baud);
(gdb) next
142 gpio_setup();
(gdb) next
143 usart_setup(baud);
(gdb) next
144 }
(gdb)
What is wrong with that picture ? :-) That makes me wonder if perhaps my
stack is screwed up somehow. That or my NVIC table is sending me here and
there. I will have to think about how that could happen (granted GDB at
system startup is notoriously challenging but this seems pretty straight
forward). I'll continue looking around.
--Chuck
On Sun, Sep 22, 2013 at 11:33 AM, Philipp Kindt <ki...@rcs.ei.tum.de> wrote:
> Hello,
>
> I am using STM32F4 discovery + libopencm3. I cannot confirm this issue.
> The USARTs run without any problem. I've tried it with and without DMA,
> however, i've never used USART 6.
> Did you make sure none of the disocovery-board peripherals uses the same
> pins your USART is configured to use? (LIS302DL, ...?)
>
> Best regards
>
> Philipp
>
>
>
> On 22.09.2013 08:57, Ken Sarkies wrote:
>
> On 22/09/13 15:06, Chuck McManis wrote:
>
> So when ever I reset my board I get 'junk' that comes out of my serial
> port. I've not quite gotten to the point where I can capture it on my scope
> yet but its annoying.
>
> I've been using the STM32F4-Discovery board, USART6 in this case, and
> something during my reset sequence seems to generate junk before stuff that
> I send for "real" actually appears. Wondering if anyone else had seen that?
>
> Not sure if I can be helpful or a nuisance. I can only verify it doesn't
> happen on the STM32F103 boards I have. Capturing it would tell if it comes
> during or after the reset. A single glitch or down transition could be
> interpreted as a start bit. Do you have hardware drivers? Are you seeing it
> on the CRO or receiving it? A good serial debug tool might be helpful to
> see what it contains if you don't have a storage CRO. If it's important to
> your application I don't mind checking it out on Tuesday and see if it's a
> "feature" of those boards.
>
> Ken
>
>
> --Chuck
>
>
>
> ------------------------------------------------------------------------------
> LIMITED TIME SALE - Full Year of Microsoft Training For Just $49.99!
> 1,500+ hours of tutorials including VisualStudio 2012, Windows 8, SharePoint
> 2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack includes
> Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/22/13.
> http://pubads.g.doubleclick.net/gampad/clk?id=64545871&iu=/4140/ostg.clktrk
>
>
>
> _______________________________________________
> libopencm3-devel mailing
> listlibopencm3-devel@lists.sourceforge.nethttps://lists.sourceforge.net/lists/listinfo/libopencm3-devel
>
>
>
>
> ------------------------------------------------------------------------------
> LIMITED TIME SALE - Full Year of Microsoft Training For Just $49.99!
> 1,500+ hours of tutorials including VisualStudio 2012, Windows 8, SharePoint
> 2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack includes
> Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/22/13.
> http://pubads.g.doubleclick.net/gampad/clk?id=64545871&iu=/4140/ostg.clktrk
>
>
>
> _______________________________________________
> libopencm3-devel mailing
> listlibopencm3-devel@lists.sourceforge.nethttps://lists.sourceforge.net/lists/listinfo/libopencm3-devel
>
>
>
>
> ------------------------------------------------------------------------------
> LIMITED TIME SALE - Full Year of Microsoft Training For Just $49.99!
> 1,500+ hours of tutorials including VisualStudio 2012, Windows 8,
> SharePoint
> 2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack
> includes
> Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/22/13.
> http://pubads.g.doubleclick.net/gampad/clk?id=64545871&iu=/4140/ostg.clktrk
> _______________________________________________
> libopencm3-devel mailing list
> libopencm3-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/libopencm3-devel
>
>
------------------------------------------------------------------------------
LIMITED TIME SALE - Full Year of Microsoft Training For Just $49.99!
1,500+ hours of tutorials including VisualStudio 2012, Windows 8, SharePoint
2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack includes
Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/22/13.
http://pubads.g.doubleclick.net/gampad/clk?id=64545871&iu=/4140/ostg.clktrk
_______________________________________________
libopencm3-devel mailing list
libopencm3-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/libopencm3-devel
