L9803 STMicroelectronics, L9803 Datasheet - Page 34

• Manufacturer Part Number: L9803
• Description: Super Smart Power Motor Driver With 8-bit Mcu, Ram, Eeprom, Adc, Wdg, Timers, Pwm And H-bridge Driver
• Manufacturer: STMicroelectronics

On-Chip Peripherals
Note:
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In case of a floating input with interrupt configuration, special care must be taken when
changing the configuration (see
The external interrupts are hardware interrupts, which means that the request latch (not
accessible directly by the application) is automatically cleared when the corresponding
interrupt vector is fetched. To clear an unwanted pending interrupt by software, the
sensitivity bits in the Miscellaneous register must be modified.
Output Mode
The output configuration is selected by setting the corresponding DDR register bit. In this
case, writing the DR register applies this digital value to the I/O pin through the latch. Then
reading the DR register returns the previously stored value.
Two different output modes can be selected by software through the OR register: Output
push-pull and open-drain.
DR register value and output pin status:
Alternate function
When an on-chip peripheral is configured to use a pin, the alternate function is automatically
selected.
This alternate function takes priority over the standard I/O programming.
When the signal is coming from an on-chip peripheral, the I/O pin is automatically
configured in output mode (push-pull or open drain according to the peripheral).
When the signal is going to an on-chip peripheral, the I/O pin must be configured in input
mode. In this case, the pin state is also digitally readable by addressing the DR register.
Input pull-up configuration can cause unexpected value at the input of the alternate
peripheral input. When an on-chip peripheral use a pin as input and output, this pin has to
be configured in input floating mode.
DR
0
1
Push-Pull
Figure
V
Vss
DD
17).
Open-drain
Floating
Vss
L9803