NAME

    Device::AVR::UPDI - interact with an AVR microcontroller over UPDI

DESCRIPTION

    This module provides a class for interacting with an AVR
    microcontroller in one of the newer ATmega 0-series, or ATtiny 0-series
    or 1-series types, which uses the UPDI programming and debug interface.

 Hardware Interface

    This code expects to find a serial port connected to the UPDI pin of
    the microcontroller as a shared single-wire interface. Suitable
    hardware to provide this can be created using a USB-UART adapter,
    connecting the RX line directly to the MCU's UPDI pin, and connecting
    TX via a current-limiting resistor of 4.7 kohm.

       +------------+                    +-------------------+
       |         RX-|-------------+      |                   |
       | USB-UART   |             +------|-UPDI              |
       |         TX-|---[ 4k7 ]---+      |  ATmega or ATtiny |
       +------------+                    +-------------------|

CONSTRUCTORS

 new

       $updi = Device::AVR::UPDI->new( ... )

    Constructs and returns a new Device::AVR::UPDI instance.

    Takes the following named arguments:

    dev => STRING

      Path to the device node representing the serial port connection.

    fh => IO

      Alternative to dev, provides an IO handle directly. This should be an
      instance of IO::Termios, or at least, provide the same interface.

    part => STRING

      Name of the AVR chip to interact with. This is used to define
      parameters like memory size and location of internal peripherals.

      Any of the following forms are accepted

         part => "ATtiny814"  | "attiny814"  | "t814"
         part => "ATmega4809" | "atmega4809" | "m4809"

    baud => INT

      Optional. Overrides the baud rate for communications. Defaults to
      115200.

      Lower numbers may be useful if communication is unreliable, for
      example over a long cable or with high capacitance or noise.

    After construction, the link must be initialised by calling "init_link"
    before any of the command methods are used.

ACCESSORS

 partinfo

       $partinfo = $updi->partinfo

    Returns the Part Info structure containing base addresses and other
    parameters which may be useful for interacting with the chip.

    The returned structure provides the following fields

       $name = $partinfo->name
    
       $sig = $partinfo->signature
    
       $addr = $partinfo->baseaddr_nvmctrl
       $addr = $partinfo->baseaddr_fuse
       $addr = $partinfo->baseaddr_flash
       $addr = $partinfo->baseaddr_eeprom
       $addr = $partinfo->baseaddr_sigrow
    
       $bytes = $partinfo->pagesize_flash
       $bytes = $partinfo->pagesize_eeprom
       $bytes = $partinfo->size_flash
       $bytes = $partinfo->size_eeprom
    
       $fusenames = $partinfo->fusenames

 fuseinfo

    Returns a data structure containing information about the individual
    fuse fields defined by this device.

    This is parsed directly from a shipped YAML file; see the files in the
    share/ directory for more details.

METHODS

 init_link

       $updi->init_link->get

    Initialise the UPDI link for proper communication.

    This method must be invoked after the object is constructed, before
    using any of the other commands.

 read_updirev

       $rev = $updi->read_updirev->get

    Reads the UPDIREV field of the STATUSA register.

 read_asi_sys_status

    Reads the ASI_SYS_STATUS register.

 read_sib

       $sib = $updi->read_sib->get

    Reads the System Information Block.

    This is returned in a HASH reference, containing four keys:

       {
          family       => "tinyAVR",
          nvm_version  => "P:0",
          ocd_version  => "D:0",
          dbg_osc_freq => 3,
       }

 read_signature

       $signature = $updi->read_signature->get

    Reads the three signature bytes from the Signature Row of the device.
    This is returned as a plain byte string of length 3.

 request_reset

       $updi->request_reset( $reset )->get

    Sets or clears the system reset request. Typically used to issue a
    system reset by momentarilly toggling the request on and off again:

       await $updi->request_reset( 1 );
       await $updi->request_reset( 0 );

 erase_chip

       $updi->erase_chip->get

    Requests a full chip erase, waiting until the erase is complete.

    After this, the chip will be unlocked.

    Takes an optional named argument:

    no_reset => BOOL

      If true, does not issue a system reset request after loading the key.
      This allows you to load multiple keys at once before sending the
      reset, which may be required e.g. to recover from a bad SYSCFG0 fuse
      setting.

         await $updi->erase_chip( no_reset => 1 );
         await $updi->enable_nvmprog;

 enable_nvmprog

       $updi->enable_nvmprog->get

    Requests the chip to enter NVM programming mode.

 write_nvm_page

       $updi->write_nvm_page( $addr, $data, $wordsize )->get

    Writes a single page into NVM controller in 8- or 16-bit word
    transfers. $addr is within the data address space. $wordsize must be
    either 8 or 16.

 erasewrite_nvm_page

    Identical to "write_nvm_page" but issues a combined erase-and-write
    command. This is the method to use for EEPROM writes.

 write_fuse

       $updi->write_fuse( $idx, $value )->get

    Writes a fuse value. $idx is the index of the fuse within the FUSES
    memory segment, from 0 onwards.

 read_fuse

       $value = $updi->read_fuse( $idx )->get

    Reads a fuse value. $idx is the index of the fuse within the FUSES
    memory segment, from 0 onwards.

SEE ALSO

      * "AVR UPDI Programming Cable"

      An adapter cable to flash firmware onto an AVR microcontroller chip
      via UPDI, compatible with this module.

      https://www.tindie.com/products/16571/

AUTHOR

    Paul Evans <leonerd@leonerd.org.uk>