Delphi/Lazarus - HAT Brick

This is the description of the Delphi/Lazarus API bindings for the HAT Brick. General information and technical specifications for the HAT Brick are summarized in its hardware description.

An installation guide for the Delphi/Lazarus API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Sleep

Download (ExampleSleep.pas)

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program ExampleSleep;

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickHAT;

type
  TExample = class
  private
    ipcon: TIPConnection;
    hat: TBrickHAT;
  public
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XXYYZZ'; { Change XXYYZZ to the UID of your HAT Brick }

var
  e: TExample;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  hat := TBrickHAT.Create(UID, ipcon);

  { Connect to brickd }
  ipcon.Connect(HOST, PORT);
  { Don't use device before ipcon is connected }

  { Turn Raspberry Pi and Bricklets off in 2 seconds for 30 minutes with sleep indicator enabled }
  hat.SetSleepMode(2, 1800, true, true, true);

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

API

Since Delphi does not support multiple return values directly, we use the out keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

Basic Functions

constructor TBrickHAT.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

hat := TBrickHAT.Create('YOUR_DEVICE_UID', ipcon);

This object can then be used after the IP Connection is connected (see examples above).

procedure TBrickHAT.SetSleepMode(const powerOffDelay: longword; const powerOffDuration: longword; const raspberryPiOff: boolean; const brickletsOff: boolean; const enableSleepIndicator: boolean)

Sets the sleep mode.

Note

Calling this function will cut the Raspberry Pi's power after Power Off Delay seconds. You have to shut down the operating system yourself, e.g. by calling 'sudo shutdown -h now'.

Parameters:

  • Power Off Delay: Time in seconds before the RPi/Bricklets are powered off.
  • Power Off Duration: Duration in seconds that the RPi/Bricklets stay powered off.
  • Raspberry Pi Off: RPi is powered off if set to true.
  • Bricklets Off: Bricklets are powered off if set to true.
  • Enable Sleep Indicator: If set to true, the status LED will blink in a 1s interval during the whole power off duration. This will draw additional 0.3mA.

Example: To turn RPi and Bricklets off in 5 seconds for 10 minutes with sleep indicator enabled, call (5, 60*10, true, true, true).

This function can also be used to implement a watchdog. To do this you can write a program that calls this function once per second in a loop with (10, 2, true, false, false). If the RPi crashes or gets stuck the HAT will reset the RPi after 10 seconds.

procedure TBrickHAT.GetSleepMode(out powerOffDelay: longword; out powerOffDuration: longword; out raspberryPiOff: boolean; out brickletsOff: boolean; out enableSleepIndicator: boolean)

Returns the sleep mode settings as set by SetSleepMode.

procedure TBrickHAT.SetBrickletPower(const brickletPower: boolean)

Set to true/false to turn the power supply of the connected Bricklets on/off.

By default the Bricklets are on.

function TBrickHAT.GetBrickletPower: boolean

Returns the power status of the connected Bricklets as set by SetBrickletPower.

procedure TBrickHAT.GetVoltages(out voltageUSB: word; out voltageDC: word)

Returns the USB supply voltage and the DC input supply voltage in mV.

There are three possible combinations:

  • Only USB connected: The USB supply voltage will be fed back to the DC input connector. You will read the USB voltage and a slightly lower voltage on the DC input.
  • Only DC input connected: The DC voltage will not be fed back to the USB connector. You will read the DC input voltage and the USB voltage will be 0.
  • USB and DC input connected: You will read both voltages. In this case the USB supply will be without load, but it will work as backup if you disconnect the DC input (or if the DC input voltage falls below the USB voltage).

Advanced Functions

function TBrickHAT.GetAPIVersion: array [0..2] of byte

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

function TBrickHAT.GetResponseExpected(const functionId: byte): boolean

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by SetResponseExpected. For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

  • BRICK_HAT_FUNCTION_SET_SLEEP_MODE = 1
  • BRICK_HAT_FUNCTION_SET_BRICKLET_POWER = 3
  • BRICK_HAT_FUNCTION_SET_VOLTAGES_CALLBACK_CONFIGURATION = 6
  • BRICK_HAT_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BRICK_HAT_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BRICK_HAT_FUNCTION_RESET = 243
  • BRICK_HAT_FUNCTION_WRITE_UID = 248
procedure TBrickHAT.SetResponseExpected(const functionId: byte; const responseExpected: boolean)

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

  • BRICK_HAT_FUNCTION_SET_SLEEP_MODE = 1
  • BRICK_HAT_FUNCTION_SET_BRICKLET_POWER = 3
  • BRICK_HAT_FUNCTION_SET_VOLTAGES_CALLBACK_CONFIGURATION = 6
  • BRICK_HAT_FUNCTION_SET_WRITE_FIRMWARE_POINTER = 237
  • BRICK_HAT_FUNCTION_SET_STATUS_LED_CONFIG = 239
  • BRICK_HAT_FUNCTION_RESET = 243
  • BRICK_HAT_FUNCTION_WRITE_UID = 248
procedure TBrickHAT.SetResponseExpectedAll(const responseExpected: boolean)

Changes the response expected flag for all setter and callback configuration functions of this device at once.

procedure TBrickHAT.GetSPITFPErrorCount(out errorCountAckChecksum: longword; out errorCountMessageChecksum: longword; out errorCountFrame: longword; out errorCountOverflow: longword)

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

function TBrickHAT.SetBootloaderMode(const mode: byte): byte

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following constants are available for this function:

  • BRICK_HAT_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICK_HAT_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICK_HAT_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICK_HAT_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICK_HAT_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
  • BRICK_HAT_BOOTLOADER_STATUS_OK = 0
  • BRICK_HAT_BOOTLOADER_STATUS_INVALID_MODE = 1
  • BRICK_HAT_BOOTLOADER_STATUS_NO_CHANGE = 2
  • BRICK_HAT_BOOTLOADER_STATUS_ENTRY_FUNCTION_NOT_PRESENT = 3
  • BRICK_HAT_BOOTLOADER_STATUS_DEVICE_IDENTIFIER_INCORRECT = 4
  • BRICK_HAT_BOOTLOADER_STATUS_CRC_MISMATCH = 5
function TBrickHAT.GetBootloaderMode: byte

Returns the current bootloader mode, see SetBootloaderMode.

The following constants are available for this function:

  • BRICK_HAT_BOOTLOADER_MODE_BOOTLOADER = 0
  • BRICK_HAT_BOOTLOADER_MODE_FIRMWARE = 1
  • BRICK_HAT_BOOTLOADER_MODE_BOOTLOADER_WAIT_FOR_REBOOT = 2
  • BRICK_HAT_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_REBOOT = 3
  • BRICK_HAT_BOOTLOADER_MODE_FIRMWARE_WAIT_FOR_ERASE_AND_REBOOT = 4
procedure TBrickHAT.SetWriteFirmwarePointer(const pointer: longword)

Sets the firmware pointer for WriteFirmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

function TBrickHAT.WriteFirmware(const data: array [0..63] of byte): byte

Writes 64 Bytes of firmware at the position as written by SetWriteFirmwarePointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

procedure TBrickHAT.SetStatusLEDConfig(const config: byte)

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following constants are available for this function:

  • BRICK_HAT_STATUS_LED_CONFIG_OFF = 0
  • BRICK_HAT_STATUS_LED_CONFIG_ON = 1
  • BRICK_HAT_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICK_HAT_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickHAT.GetStatusLEDConfig: byte

Returns the configuration as set by SetStatusLEDConfig

The following constants are available for this function:

  • BRICK_HAT_STATUS_LED_CONFIG_OFF = 0
  • BRICK_HAT_STATUS_LED_CONFIG_ON = 1
  • BRICK_HAT_STATUS_LED_CONFIG_SHOW_HEARTBEAT = 2
  • BRICK_HAT_STATUS_LED_CONFIG_SHOW_STATUS = 3
function TBrickHAT.GetChipTemperature: smallint

Returns the temperature in °C as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

procedure TBrickHAT.Reset

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

procedure TBrickHAT.WriteUID(const uid: longword)

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

function TBrickHAT.ReadUID: longword

Returns the current UID as an integer. Encode as Base58 to get the usual string version.

procedure TBrickHAT.GetIdentity(out uid: string; out connectedUid: string; out position: char; out hardwareVersion: array [0..2] of byte; out firmwareVersion: array [0..2] of byte; out deviceIdentifier: word)

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c' or 'd'.

The device identifier numbers can be found here. There is also a constant for the device identifier of this Brick.

Callback Configuration Functions

procedure TBrickHAT.SetVoltagesCallbackConfiguration(const period: longword; const valueHasToChange: boolean)

The period in ms is the period with which the OnVoltages callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

The default value is (0, false).

New in version 2.0.1 (Firmware).

procedure TBrickHAT.GetVoltagesCallbackConfiguration(out period: longword; out valueHasToChange: boolean)

Returns the callback configuration as set by SetVoltagesCallbackConfiguration.

New in version 2.0.1 (Firmware).

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done by assigning a procedure to an callback property of the device object:

procedure TExample.MyCallback(sender: TBrickHAT; const param: word);
begin
  WriteLn(param);
end;

hat.OnExample := {$ifdef FPC}@{$endif}example.MyCallback;

The available callback property and their type of parameters are described below.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

property TBrickHAT.OnVoltages
procedure(sender: TBrickHAT; const voltageUSB: word; const voltageDC: word) of object;

This callback is triggered periodically according to the configuration set by SetVoltagesCallbackConfiguration.

The parameters are the same as GetVoltages.

New in version 2.0.1 (Firmware).

Constants

const BRICK_HAT_DEVICE_IDENTIFIER

This constant is used to identify a HAT Brick.

The GetIdentity function and the TIPConnection.OnEnumerate callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

const BRICK_HAT_DEVICE_DISPLAY_NAME

This constant represents the human readable name of a HAT Brick.