GPIO 4 always holds high voltage?

Dear All,

I use C6424 EVM. I want to configue GPIO4 as an interrupt source. My program doesn't work. No interrupt has been detected. So I try to test GPIO4 pin characteristic not considering interrupt issue. I found that GPIO 4 pin always hold high voltage regardless of setting or clearing the correspond bit in the registers and being configured as input or output pin.

Further I tested from GPIO0 to GPIO31, it is found that:
GPIO 3:0 can reflect properly the voltage level set in IN_DATA register.
GPIO 12:4 can not, all hold low voltage (0 v) except GPIO 4 holding high voltage (3.27 v).
GPIO 13 can.
GPIO 21:14 can not, all with low voltage.
GPIO 29:22 OK
GPIO 30, not with low voltage.
GPIO 31 OK.

I checked GPIO user guide and I think I have set properly the PINMUX, VDD3P3V and PSC.

It is very strange. Could anyone please help me out?

Regards,
Louis Start a New Thread

Yang,

There are several register values related to each GPIO pin.

These include the internal pull up/pull down settings,
the pin direction, the pin value, AND what is connected to the pin on the rest
of the board you are using.

Then, after setting up the above, for use as an interrupt, there is a register
to set a couple of bits in to say if the interrupt is rising or falling edge or
level activated.

Then, there is the enabling of the global interrupt and that specific interrupt.

There needs to be a interrupt handler and the address of the interrupt handler
in the interrupt vector table.

Finally, the interrupt pending must be cleared, so a new interrupt can occur.

---------- Original Message -----------
From: "Yang, Chunhua"
To:
Sent: Mon, 22 Sep 2008 17:48:24 +0100
Subject: [c6x] GPIO 4 always holds high voltage?

> Dear All,
>
> I use C6424 EVM. I want to configue GPIO4 as an interrupt source. My
> program doesn't work. No interrupt has been detected. So I try to test
> GPIO4 pin characteristic not considering interrupt issue. I found
> that GPIO 4 pin always hold high voltage regardless of setting or
> clearing the correspond bit in the registers and being configured as
> input or output pin.
>
> Further I tested from GPIO0 to GPIO31, it is found that:
> GPIO 3:0 can reflect properly the voltage level set in IN_DATA
> register. GPIO 12:4 can not, all hold low voltage (0 v) except GPIO 4
> holding high voltage (3.27 v). GPIO 13 can. GPIO 21:14 can not, all
> with low voltage. GPIO 29:22 OK GPIO 30, not with low voltage. GPIO 31
> OK.
>
> I checked GPIO user guide and I think I have set properly the PINMUX,
> VDD3P3V and PSC.
>
> It is very strange. Could anyone please help me out?
>
> Regards,
> Louis
------- End of Original Message ------- Start a New Thread