Class _ioa: General Purpose Input/Output

This class implements a group of consecutive I/O pins inside the same _gpa GPIO port. It handles not-connected pins and triggers an error if such a pin is addressed (but no error is triggered if you access the registers directly).

It supports HW_ADDRESS(), HW_BITS(), and HW_POSITION().

Relatives

IOs are relatives of their port:

• (porta,1): pin PA1
• (portb,4,2): pins PB5 PB4 PB3 PB2

and have their port as relative:

• ((portb,1),port): portb

Single IO pins can be designated as relatives of the virtual pin object:

• (pin,int0): pin named int0
• (pin,1): pin number 1 (depends on the package of the device)

Analog input pins have a did register that disables the digital input stage:

• (portb,1,0,did): DID logical register for PB0

Interface

---

hw( configure, IO, ... ) and hwa( configure, IO, ... ) configure an IO:

hw | hwa( configure,   (porta,0),
 
        [ function,    gpio, ]                       // Default, no other choice
 
          mode,        digital_input
                     | digital_input_floating        // Reset value
                     | digital_input_pullup
                     | digital_output | digital_output_pushpull
                     | analog_input
                     | analog_input_floating
                     | analog_input_pullup
);

Note

Atmel AVR peripheral controllers take care of their I/O configuration, so there is no need for a 'function' parameter for IOs as it is always 'gpio'.

A digital output in high state enables its pull-up when switched to an input.

---

hw( read, IO, ... ) returns the state of the IO:

uint8_t value = hw( read, (porta,0) );

---

hw( write, IO, value ) and hwa( write, IO, value ) set the state of an IO:

hw | hwa( write, (porta,0), 1 );     // PA0 = 1
hw | hwa( write, (portb,2,4), 2 );   // PB5,PB4 = 1,0

---

hw( set, IO ) and hwa( set, IO ) set all the bits of the IO to 1:

hw | hwa( set, (porta,0) );          // PA0 = 1
hw | hwa( set, (portb,2,4) );        // PB5,PB4 = 1,1

---

hw( clear, IO ) and hwa( clear, IO ) clear all the bits of the IO:

hw | hwa( clear, (porta,0) );        // PA0 = 0
hw | hwa( clear, (portb,2,4) );      // PB5,PB4 = 0,0

---

hw( toggle, IO ) and hwa( toggle, IO ) toggle all the bits of the IO:

hw( toggle, (porta,0) );             // Toggle pin PA0

hwa( toggle, (porta,0) );            //  Register PA0 for toggling
hwa( toggle, (porta,2,3) );          //  Register PA4 and PA3 for toggling
hwa( commit );                       //  Toggle PA0, PA4 and PA3 at once