From: Daniel W. <da...@wi...> - 2006-09-04 22:33:17
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<html><head><meta name=3D"Generator" content=3D"PSI HTML/CSS Generator"/> <style type=3D"text/css"><!-- body{font-family:'Tahoma';font-size:10pt;font-color:'#000000';} LI{display:list-item;margin:0.00in;} p{display:block;margin:0.00in;} --></style> </head><BODY BGCOLOR=3D"#A8D9D7" ><div><SPAN= style=3D"font-family:'Arial';font-size:10pt;">I tried power up on power brick= and gpio's came up in known state.</SPAN></div> <div> </div> <div><SPAN style=3D"font-family:'Arial';font-size:10pt;">USB power seems to= make them come up in unknown state.</SPAN></div> <div> </div> <div><SPAN style=3D"font-family:'Arial';font-size:10pt;">Dan.</SPAN></div> </body></html> |
From: Dave H. <dhy...@gm...> - 2006-09-04 23:49:34
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On 9/4/06, Daniel Winsor <da...@wi...> wrote: > > I tried power up on power brick and gpio's came up in known state. > > USB power seems to make them come up in unknown state. Can you provide a clearer example? Like a particular GPIO that comes up in an unknown state? You need to keep in mind that many of the pins are not configured as GPIO lines, but rather as alternate functions. So it's also useful to distinguish between pins and GPIO states (which aren't necessarily the same). -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |
From: Daniel W. <da...@wi...> - 2006-09-04 23:56:42
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<html><head><meta name=3D"Generator" content=3D"PSI HTML/CSS Generator"/> <style type=3D"text/css"><!-- body{font-family:'Tahoma';font-size:10pt;font-color:'#000000';} LI{display:list-item;margin:0.00in;} p{display:block;margin:0.00in;} body{} --></style> </head><BODY BGCOLOR=3D"#A8D9D7" ><div><SPAN style=3D"font-size:10pt;">I'm using= the GPIO UCB 0,1 inputs and 2,3 outputs.</SPAN></div> <div><SPAN style=3D"font-size:10pt;">I see 2 and 3 coming up low or inactive.= when low, it would turn on the motor.</SPAN></div> <div> </div> <div><SPAN style=3D"font-size:10pt;">dan.<br /><br /></span></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> On 9/4/06, Daniel Winsor= wrote:</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">></SPAN></div> <div><SPAN style=3D"font-size:10pt;color:maroon;">>> I tried power up on= power brick and gpio's came up in known state.</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:maroon;">>></SPAN></div> <div><SPAN style=3D"font-size:10pt;color:maroon;">>> USB power seems to= make them come up in unknown state.</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:maroon;">>></SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> Can you provide a clearer= example? Like a particular GPIO that</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> comes up in an unknown= state?</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">></SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> You need to keep in mind= that many of the pins are not configured</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> as GPIO lines, but rather= as alternate functions. So it's also</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> useful to distinguish= between pins and GPIO states (which aren't</SPAN></div> <div><SPAN style=3D"font-size:10pt;color:navy;">> necessarily the= same).</SPAN></div> </body></html> |
From: Chris D. <cg...@co...> - 2006-09-05 00:14:09
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On 9/4/06, Daniel Winsor <da...@wi...> wrote: > I'm using the GPIO UCB 0,1 inputs and 2,3 outputs. > I see 2 and 3 coming up low or inactive. when low, it would turn on the > motor. Dan, Just a FYI: it's important to differentiate between GPIOs on the gumstix (controlled by the PXA255), and the UCB1700-controlled GPIOs on the audiostix -- especially since the audiostix2 breaks out many of the PXA GPIO lines. best, -chris |
From: Dave H. <dhy...@gm...> - 2006-09-05 00:39:33
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Hi Dan, > I'm using the GPIO UCB 0,1 inputs and 2,3 outputs. > I see 2 and 3 coming up low or inactive. when low, it would turn on the > motor. Ahhh. I'm not very familiar with the UCB 1400. I downloaded the datasheet, and it says that the IO pins are all configured as inputs by default. So if you have an output connected, then the value that you measure will be indeterminate until such time as the IO pin is configured as an output. The normal way of dealing with this is to use a pullup/pulldown resistor on the line that will control the pin when the pin is configured as an input, but will be overriden when the pin is an output. You should be able to pick a fairly large resistor, like 20K-47K. -- Dave Hylands Vancouver, BC, Canada http://www.DaveHylands.com/ |