User manual

...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 750
www.energymicro.com
MODEx Input Output DOUT Pull-
down
Pull-
up
Alt.
strength
Input
Filter
Description
0 On On Input enabled with pull-down and
filter
0b0011
1 On On Input enabled with pull-up and filter
0b0100 x Push-pull
0b0101
Push-pull
x On Push-pull with alt. drive strength
0b0110 x Open-source
0b0111
Open
Source
(Wired-OR)
x On Open-source with pull-down
0b1000 x Open-drain
0b1001 x On Open-drain with filter
0b1010 x On Open-drain with pull-up
0b1011 x On On Open-drain with pull-up and filter
0b1100 x On Open-drain with alt. drive strength
0b1101 x On On Open-drain with alt. drive strength
and filter
0b1110 x On On Open-drain with alt. drive strength
and pull-up
0b1111
Open Drain
(Wired-
AND)
x On On On Open-drain with alt. drive strength,
pull-up and filter
MODEn determines which mode the pin is in at a given time. Setting MODEn to 0b0000 disables the
pin, reducing power consumption to a minimum. When the output driver is disabled, the pin can be used
as a connection for an analog module (e.g. ADC, LCD...). Input is enabled by setting MODEn to any
value other than 0b0000. The pull-up, pull-down and filter function can optionally be applied to the input,
see Figure 32.2 (p. 750) .
The internal pull-up resistance, R
PU
, and pull-down resistance, R
PD
, are defined in the device datasheet.
When the filter is enabled it suppresses glitches with pulse widths as defined by the parameter t
IOGLITCH
in the device datasheet.
Figure 32.2. Tristated Output with Optional Pull-up or Pull-down
V
DD
DIN
Optional
pull-up
V
SS
Optional
pull-down
Input enable
Analog connection
Glitch
suppression
filter
Filter enable
When MODEn=0b0100 or MODEn=0b0101, the pin operates in push-pull mode. In this mode, the pin
is driven either high or low, dependent on the value of GPIO_Px_DOUT. The push-pull configuration is
shown in Figure 32.3 (p. 751) .