Content originally posted in LPCWare by plebi on Thu Mar 31 05:42:44 MST 2011
hi,
Im using small_gpio library to change states of IO ports and functions of IO ports.
Everythings works well instead of ports 1.1 and 1.0.
At start im changing functions of these ports to GPIO, pullup, and output (after reset were different).
And then,
Port 1_1 works sometimes as input, sometimes as output - his function has been chaged because it works as bidirectional data port.
Simple:
port 1_1 - bidirectional data
port 1_0 - output clock
and there is a problem with changing function of 1_1 port from input to output.
When function is changed to output (from input) and his state should be HI (3V) on port I measure about 0.5V !!. And this value has been changed to 3V when on CLK port (1_0) value is chaged to HIGH.
Instead of this one (first) pulse ports works well.
Change from output to input works also well.
Can anyone help me and explain why ?
On both IO ports are connected resistors 10k to VCC(3V) as external pull up.
Problem was ilustrated on picture below.
Thnax
plebi