Issue with GPIO driver on AM1808

Hi,

We are working with custom AM1808 board,need to program a peripheral device over a single wire interface using GPIO.

We are drive GPIO from logic high to Tri-state and then back to logic low.
for data pattern 1 and 0.

NOTE:

GPIO of concern is GP8[11],using linux gpio driver.

At kernel level in da850.c pinmuxs have been configured for GPIO mode

for GP8[11].

At user space:

./gpiotoggle 139

echo $1 > /sys/class/gpio/export
while [ 1 ]
do
echo 1 > /sys/class/gpio/gpio$1/value
echo "out" > /sys/class/gpio/gpio$1/direction
sleep 0.001
echo "in" > /sys/class/gpio/gpio$1/direction
sleep 0.00001
echo 1 > /sys/class/gpio/gpio$1/value
echo "out" > /sys/class/gpio/gpio$1/direction
sleep 0.001
echo "in" > /sys/class/gpio/gpio$1/direction
sleep 0.00001
done

Observations:
1>On driving GPIO to LOW : 0.0V is observed

2>On driving GPIO to Tristate from LOW:1.8 V is observed

3>On driving GPIO to HIGH from Tristate: 1.8 is observed instead of 3.3 V

4>On driving GPIO to LOW from tristate :0V is observed

Is any body facing similar issue ? how to fix this issue .

Thanks in advance for any suggestions,

-

Gururaj