Re: [Gumstix-users] ttyS1 Pins?

[<jer...@gm...>]

Reading this thread, my simple question is : can we use 4 ttyS at the same=
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time or 3ttyS+bt without interfering with usb or other stuff?
If it isn't possible, can we hot-switch gpio from ttyS to usb (for example)=
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?


2005/8/4, Dave Hylands <dhy...@gm...>:
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> Hi Brad,
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> > This drifts into territory I was trying to figure out...
> >
> > the way the current kernel works, without any tweaking, isn't the
> > infineon serial port (ttyS3) aliased to BT_UART? But what serial port i=
s
> > aliased to HW_UART?
> >
> > If the answer is "use the source" where do I look?
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> Here's what I did to figure it out - since I didn't know either before
> you asked :)
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> The boot sequence is that /etc/inittab is read, and it says (under
> sysinit) to run /etc/init.d/rcS start. rcS in turn runs all of the
> /etc/init.d/S* files, which includes S30bluetooth. In S30bluetooth
> you'll see that it does a modprobe of gumstix_bluetooth.
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> Searching through the source tree:
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> cd gumstix-buildroot/build_arm/linux-2.6.11gum
> find . -name Makefile -exec fgrep gumstix_bluetooth {} \; -print
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> leads to the net/bluetooth directory, where we can see that
> gumstix_bluetooth.c is used to build the gumstix_bluetooth module.
> When the module is loaded, the module_init macro causes the
> gumstix_bluetooth_init function to be called, and this is where it
> initializes GPIO's 42, 43, 44, and 45 to be the HW-UART versions.
> These GPIO's are the ones which connect to the bluetooth chip.
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> Chapter 4 of the PXA 255 Developer's manual gives a nice summary of
> all of the GPIO functions and which AF's correspond to a particular
> function.
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> So, the HWUART (ttyS3) is connected to the bluetooth chip. BTUART
> (ttyS1) could be configured (and used to be - I noticed that the
> comment in gumstix_bluetooth.c doesn't match the code).
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> During bootup, the following is displayed on the console:
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> ttyS0 at MMIO 0x40100000 (irq =3D 15) is a FFUART
> ttyS1 at MMIO 0x40200000 (irq =3D 14) is a BTUART
> ttyS2 at MMIO 0x40700000 (irq =3D 13) is a STUART
> ttyS3 at MMIO 0x41600000 (irq =3D 0) is a HWUART
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> which shows you the mapping of tty's to UARTs. The file
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> --
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
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Jerome