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Questions about GPIO J900 and mux.

posted in Uncategorized
Thursday, January 05 2012, 08:13 PM
0
Hello everybody, I have been fighting lot of time until I have decided to came to this forum to try to solve my questions and now to ask directly. My IGEPV2 RC1 has the linux kernel 2.6.35-23 and I want to use several GPIO pins and one PWM of J900. I have checked on the forum that in order to configure the GPIO I should change the mux to 4 on the kernel with something like this: MUX_VAL(CP(MCBSP3_CLKX), (IEN | PTD | DIS | M4)) Can somebody explain me how to do it? If I want to use a PWM line, should I change the mux of 4, 8 or 10 pin to 3 on the kernel? And a question else, If I would like to use the WLAN also, there is some problem as I am using GPIO?? Thank you very much.
Responses (7)
  • Accepted Answer

    mcaro
    mcaro
    Offline
    Monday, January 09 2012, 10:39 AM - #permalink
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    Hi Martin, The more easy way for modify the MUX it\\\'s using the kernel: [url=http://git.igep.es/?p=pub/scm/linux-omap-2.6.git;a=blob;f=arch/arm/mach-omap2/board-igep0020.c;h=7a13af616081a2a0fd8b11f2289e72800644a8fc;hb=refs/heads/linux-2.6.37.y#l334]http://git.igep.es/?p=pub/scm/linux-oma ... .37.y#l334[/url] Here you\\\'ve how we setup the mux, you should add or modify your wished configuration and rebuild the kernel. You\\\'re talking about gpios and pwm, I suggest you read this wiki doc (it\\\'s not finish yet so it\\\'s working in progress but I think it could be helpful for you). [url=http://labs.igep.es/index.php/Mux_configuration]http://labs.igep.es/index.php/Mux_configuration[/url] What exactly PWM you see in J990 connector? Manel
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  • Accepted Answer

    Monday, January 09 2012, 04:28 PM - #permalink
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    Hi Manel, Thank you for your answer. About PWM, I have checked on the HW_USER_MANUAL in the J900 section (see the image) in the Table 5 that exist 3 pins we can configure as PWM(the last 3 red lines in the table). This pins are 4, 8 and 10. I would like to know how i should configure the mux to use the PWM signal.
    [img]http://igep.es/images/fbfiles/images/PWM.jpg[/img]
    Thanks in advance. Jose.
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  • Accepted Answer

    Friday, January 13 2012, 10:21 AM - #permalink
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    Please, can somebody explain how to configure and use the PWM??? Or give me some link with the explanation?? Thx
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  • Accepted Answer

    Wednesday, January 25 2012, 09:50 AM - #permalink
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    Hi, Unfortunately there is no PWM driver in kernel that exports this functionality to the userspace, but you can write directly to the PWM register to enable this functionality. As a reference see [url=http://www.jumpnowtek.com/index.php?option=com_content&view=article&id=56&Itemid=63]http://www.jumpnowtek.com/index.php?opt ... &Itemid=63[/url] Hope it helps you.
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  • Accepted Answer

    Monday, March 12 2012, 08:11 PM - #permalink
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    Thank you. But do you mean that i cannot use the module described on \\\"PWM Kernel Module\\\" section on the page you sent me??? I mean, for use PWM i just can do it with \\\"Command Line - /dev/mem\\\"?
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  • Accepted Answer

    Thursday, March 15 2012, 10:41 AM - #permalink
    0
    No, sorry you could use the PWM Kernel Module if it compiles. OTOH, I checked the J990 connector and seems documentation is wrong. As you see these pins are marked in red but in any place explains why this is marked in red. This is because the PWM signals are not available for these pins. The manual need to be revised, we\\\'ll update the documentation ASAP, sorry for the inconvenience.
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  • Accepted Answer

    Thursday, March 15 2012, 11:34 AM - #permalink
    0
    So, in which pins of the IGEP are connected the PWM signal of the OMAP?? If they are connected. Thank you very much!
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