ST7LITE20F2 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
ST7LITE20F2
STMicroelectronics
'ST7LITE20F2' PDF : 166 Pages View PDF
ST7LITE20F2 ST7LITE25F2 ST7LITE29F2
I/O ports
Table 23. I/O configurations (continued)
I/O port
Hardware configuration
Open-drain
output(2)
PAD
VDD
NOTE 3
RPU
DR register access
DR
register
R/W
Databus
Push-pull
output(3)
PAD
NOTE 3
VDD
RPU
DR register access
DR
register
R/W
Databus
Alternate
Enable
bit
Alternate
output
From on-chip peripheral
1. When the I/O port is in input configuration and the associated alternate function is enabled as an output,
reading the DR register will read the alternate function output status.
2. When the I/O port is in output configuration and the associated alternate function is enabled as an input,
the alternate function reads the pin status given by the DR register content.
3. For true open drain, these elements are not implemented.
Analog alternate function
Configure the I/O as floating input to use an ADC input. The analog multiplexer (controlled
by the ADC registers) switches the analog voltage present on the selected pin to the
common analog rail, connected to the ADC input.
Analog recommendations
Do not change the voltage level or loading on any I/O while conversion is in progress. Do not
have clocking pins located close to a selected analog pin.
Warning: The analog input voltage level must be within the limits
stated in the absolute maximum ratings.
10.3
I/O port implementation
The hardware implementation on each I/O port depends on the settings in the DDR and OR
registers and specific I/O port features such as ADC input or open drain.
Switching these I/O ports from one state to another should be done in a sequence that
prevents unwanted side effects. Recommended safe transitions are illustrated in Figure 32.
Other transitions are potentially risky and should be avoided, since they may present
unwanted side-effects such as spurious interrupt generation.
Doc ID 8349 Rev 5
67/166
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