Strange usart behavior

[mailmail9116]

Posted on January 20, 2013 at 15:53

Hi,

It does not matter if i config usart or not,when i open hyperterminal,and execute my program,i am getting junk on the screen ,like this :

þÿÿÿÿÿøÿþÿÿÿÿÿÿÿþÿÿüÿÿÿÿÿÿÿúÿÿÿÿÿòþÿÿÿÿÿÿÿÿÿÿþÿÿÿþÿÿþÿþþÿÿøþÿÿÿÿÿÿÿÿþøÿÿðÿÿÿÿÿÿöÿÿþÿÿþÿþÿÿÿÿÿÿÿÿÿÿÿÿþÿÿÿÿÿÿöÿÿÿÿþÿÿÿøÿÿÿÿÿþÿÿÿÿþÿÿÿÿÿöÿþÿÿÿÿöþÿþ÷ÿÿÿñþÿðÿìÿÿÿÿüÿÿÿÿÿÿÿÿüÿþÿÿòÿÿÿÿÿÿÿÿöþÿÿþþÿÿþ

What maybe the problem? i am also using sd card interface ,maybe there are some grounding issues ?

Thanks

Michael

[Tesla DeLorean]

Posted on January 20, 2013 at 16:19

Stick a scope on the pin and see if the signal occurs when you're accessing the SD card or other interfaces. If you can figure out the nature of the signal and when it occurs you'll be able to bisect the issue and debug it.

More likely a short, or a conduction path via a resistor or chip pin.

[mailmail9116]

Posted on January 21, 2013 at 10:41

Hi Clive,

its the stm3240g-eval board,in the board manual it says :

A 1 Gbyte or more MicroSD Card connected to the STM32F407IGH6 SDIO is available on the board. MicroSD Card detection is managed by the standard I/O port PH13. The MicroSD Card shares I/Os with motor control, RS-232 and audio

meaning that the sd card and the usart shar the I/O,is there anyway that i can use simultaniosaly the usart and the microSD?

Thanks

[Andrew Neil]

Posted on January 21, 2013 at 14:19

''the SD card and the usart share the I/O, is there anyway that i can use simultaniosaly the usart and the microSD?''

 

I find this the fundamental problem with ''DevKits'' that come loaded with loads of peripherals!

You'll just have to look at the board schematics and see what you can figure out...

It might be easier to use a Discovery board instead...