GPIO pins only drive to 2.7v instead of 3.3v from userspace

Started by TCash, November 25, 2015, 06:30:02 pm

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TCash

Hello All,

We have a A20 - lime2 running debian 7 with kernal 3.4.75.

when setting a gpio pin high using the linux userspace method, the gpio pins seem to only drive to 2.7 volts instead of 3.3.  Have anyone else had this issue?  The board is running fine otherwise, and we've tested on multiple lime2 boards and the behavior is the same.

Here's a snippet of our fex file:
gpio_para]
gpio_used = 1
gpio_num = 64
gpio_pin_1 = port:PG00<1>
gpio_pin_2 = port:PG01<0><default><default><default>
gpio_pin_3 = port:PG02<0><default><default><default>
gpio_pin_4 = port:PG03<0><default><default><default>
gpio_pin_5 = port:PG04<0><default><default><default>
gpio_pin_6 = port:PG05<0><default><default><default>
gpio_pin_7 = port:PG06<0><default><default><default>
gpio_pin_8 = port:PG07<0><default><default><default>
...
..


And the routine for setting the pin high:
cd /sys/class/gpio/
echo 1 > export
cd gpio1_pg0
echo "out" > direction
echo 1 > value


Thanks,
Trevor

JohnS

Sounds plausible.

Do you need higher volts and if so why?

John