Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
91
/
631
Input mode
When I/O port is configured in input mode:
Schmitt trigger input is activated
Whether the pull-up and pull-down resistors are connected depends on the configuration of the GPIO_PUPD
register
Output buffer is disabled
The data appearing on the I/O pin is sampled into the input data register
Get I/O status by read access to data register
Figure 5-2
Input floating/pull-up/pull-down configuration
Output mode
When I/O port is configured as output mode:
Schmidt trigger input is activated
Whether the pull-up and pull-down resistors are connected depends on the configuration of the GPIO_PUPD
register
Output buffer is activated
◆
Open-drain mode: '0' on the output dataregister activates N-MOS, and the pin outputs low level.
The '1' port on the output data register is placed in a high impedance state (P-MOS is
never activated)
I/O Pin
V
DD
V
SS
V
SS
Pull
up
Pull
down
diode
On
Off
Input data
register
Read
TTL Schmitt
trigger
On
On
Off
Write
Bit set/clear
register
Output data
register
Read /
Write