_iob objects are groups of one or more consecutive pins inside the same port.

Relatives

port: the GPIO port the I/O pertains to.

Interface

HW_ADDRESS() returns an address for an I/O definition, computed as:

 address_of_port + (number_of_bits-1)*16 + position_of_lsb

Ports are mapped every 0x0400 bytes in memory.

#if HW_ADDRESS(LED) == HW_ADDRESS((porta,9))
// LED is connected on pa9, or LED and pa9 do not exist.
#else
// LED is not connected on pa9, or pa9 or LED does not exist.
#endif

HW_BITS() returns the number of bits of an I/O definition:

#if (HW_ADDRESS((porta,3)) != -1) && (HW_BITS((porta,3)) != 1)
#  error HWA is damaged!
#endif

HW_POSITION() returns the position of the least significant bit:

#if (HW_ADDRESS((porta,3)) != -1) && (HW_POSITION((porta,3)) != 3)
#  HWA is damaged!
#endif

Configuration

hw|hwa( configure,   (porta,0),
      
      [ function,    gpio, ]                                 // Default
      
        mode,        digital_input | digital_input_floating  // Default
                   | digital_input_pullup
                   | digital_input_pulldown
                   | analog_input
                   | digital_output | digital_output_pushpull
                   | digital_output_opendrain,
      
        // Only for output modes
        //
      [ frequency,   low | lowest
                   | medium
                   | fast
                   | high | highest ] );

Read

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

Toggle

Toggles one or several consecutive pins at once.

Note: toggle is not atomic: it reads the ODR, then sets/resets the relevant bits through the BSRR. The ODR is not written directly.

hw( toggle, (porta,0) );

hwa( toggle, (porta,0) );       //  Register PA0 for toggling
hwa( toggle, (porta,4) );       //  Register PA4 for toggling
hwa( commit );                  //  Toggle PA0 and PA4 at once

Write

hw|hwa( write, (porta,0), 0 );

Note: HWA does not write the ODR of the port. It writes the BSRR so that atomicity is guaranted and concurrent tasks can write different pins of the port without conflict.