User manual

Hardware Description

5.7. Reset Controller (RSTC)

The embedded microcontroller has an integrated Reset Controller which samples the

backup and the core voltage. The presence of a backup voltage (VDDBU) when the card

is powered down speeds up the boot time of the microcontroller.

5.8. Peripheral Input/Output Controller (PIO)

The StampA5D3x has a maximum of 150 freely programmable digital I/O ports on its

connectors. These pins are also used by other peripheral devices.

The Parallel Input/Output Controller(PIO) manages up to 32 programmable I/O ports. Each

I/O port is associated with a bit number in the 32 bit register of the user interface. Each I/O

port may be configured for general purpose I/O or assigned to a function of an integrated

peripheral device. In doing so multiplexing with multiple integrated devices is possible.

That means a pin may be used as GPIO or only as one of the peripheral functions. The

PIO Controller also features a synchronous output providing up to 32 bits of data output

in a single write operation.

The following characteristics are individually configurable for each PIO pin:

• PIO enable

• Peripheral enable

• Output enable

• Output level

• Write Enable

• Level change interrupt

• Glitch filter: pulses that are lower than a half clock cycle are ignored

• Open-drain outputs

• Pull-up resistor

All configurations as well as the pin status can be read back by using the appropriate

status register. Multiple pins of each PIO can also be written simultaneously by using the

synchronous output register.

For interrupt handling, the PIO Controllers are considered as user peripherals. This means

that the PIO Controller interrupt lines are connected among the interrupt sources 2 to

31. Refer to the PIO Controller peripheral identifier Table B.1, “Peripheral Identifiers”

to identify the interrupt sources dedicated to the PIO Controllers. The PIO Controller

interrupt can be generated only if the PIO Controller clock is enabled.

A number of the PIO signals might be used internally on the module. Care has to be taken

when accessing the PIO registers in order not to change the settings of these internal

signals, otherwise a system crash is likely to happen.