Software / API Bindings / Go / API Reference and Examples / Bricks / HAT Brick

Go - HAT Brick¶

This is the description of the Go 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 Go API bindings is part of their general description. Additional documentation can be found on godoc.org.

Examples¶

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

Sleep¶

Download (example_sleep.go)

package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/hat_brick"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
)

const ADDR string = "localhost:4223"
const UID string = "XXYYZZ" // Change XXYYZZ to the UID of your HAT Brick.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    hat, _ := hat_brick.New(UID, &ipcon) // Create device object.

    ipcon.Connect(ADDR) // Connect to brickd.
    defer ipcon.Disconnect()
    // 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)

    fmt.Print("Press enter to exit.")
    fmt.Scanln()
}

Print Voltages¶

Download (example_print_voltages.go)

package main

import (
    "fmt"
    "github.com/Tinkerforge/go-api-bindings/hat_brick"
    "github.com/Tinkerforge/go-api-bindings/ipconnection"
)

const ADDR string = "localhost:4223"
const UID string = "XXYYZZ" // Change XXYYZZ to the UID of your HAT Brick.

func main() {
    ipcon := ipconnection.New()
    defer ipcon.Close()
    hat, _ := hat_brick.New(UID, &ipcon) // Create device object.

    ipcon.Connect(ADDR) // Connect to brickd.
    defer ipcon.Disconnect()
    // Don't use device before ipcon is connected.

    // Get current get voltages.
    voltageUSB, voltageDC, _ := hat.GetVoltages()

    fmt.Printf("Voltage USB: %f V\n", float64(voltageUSB)/1000.0)
    fmt.Printf("Voltage DC: %f V\n", float64(voltageDC)/1000.0)

    fmt.Print("Press enter to exit.")
    fmt.Scanln()
}

API¶

The HAT Brick API is defined in the package github.com/Tinkerforge/go-api-bindings/hat_brick

Nearly every function of the Go bindings can return an ipconnection.DeviceError, implementing the error interface. The error can have one of the following values:

ipconnection.DeviceErrorSuccess = 0
ipconnection.DeviceErrorInvalidParameter = 1
ipconnection.DeviceErrorFunctionNotSupported = 2
ipconnection.DeviceErrorUnknownError = 3

which correspond to the values returned from Bricks and Bricklets.

All functions listed below are thread-safe.

Basic Functions¶

func hat_brick.New(uid string, ipcon *IPConnection) (device HATBrick, err error)¶

Parameters:	uid – Type: string ipcon – Type: *IPConnection
Returns:	device – Type: HATBrick err – Type: error

Creates a new HATBrick object with the unique device ID uid and adds it to the IPConnection ipcon:

device, err := hat_brick.New("YOUR_DEVICE_UID", &ipcon)

This device object can be used after the IPConnection has been connected.

func (*HATBrick) SetSleepMode(powerOffDelay uint32, powerOffDuration uint32, raspberryPiOff bool, brickletsOff bool, enableSleepIndicator bool) (err error)¶

Parameters:	powerOffDelay – Type: uint32, Unit: 1 s, Range: [0 to 2³² - 1] powerOffDuration – Type: uint32, Unit: 1 s, Range: [0 to 2³² - 1] raspberryPiOff – Type: bool brickletsOff – Type: bool enableSleepIndicator – Type: bool
Returns:	err – Type: error

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 before the RPi/Bricklets are powered off.
Power Off Duration: Duration 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.

func (*HATBrick) GetSleepMode() (powerOffDelay uint32, powerOffDuration uint32, raspberryPiOff bool, brickletsOff bool, enableSleepIndicator bool, err error)¶

Returns:	powerOffDelay – Type: uint32, Unit: 1 s, Range: [0 to 2³² - 1] powerOffDuration – Type: uint32, Unit: 1 s, Range: [0 to 2³² - 1] raspberryPiOff – Type: bool brickletsOff – Type: bool enableSleepIndicator – Type: bool err – Type: error

Returns the sleep mode settings as set by SetSleepMode().

func (*HATBrick) SetBrickletPower(brickletPower bool) (err error)¶

Parameters:	brickletPower – Type: bool, Default: true
Returns:	err – Type: error

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

func (*HATBrick) GetBrickletPower() (brickletPower bool, err error)¶

Returns:	brickletPower – Type: bool, Default: true err – Type: error

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

func (*HATBrick) GetVoltages() (voltageUSB uint16, voltageDC uint16, err error)¶

Returns:	voltageUSB – Type: uint16, Unit: 1 mV, Range: [0 to 2¹⁶ - 1] voltageDC – Type: uint16, Unit: 1 mV, Range: [0 to 2¹⁶ - 1] err – Type: error

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

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¶

func (*HATBrick) SetRTCDriver(rtcDriver uint8) (err error)¶

Parameters:	rtcDriver – Type: uint8, Range: See constants
Returns:	err – Type: error

Configures the RTC driver that is given to the Raspberry Pi to be used. Currently there are two different RTCs used:

Hardware version <= 1.5: PCF8523
Hardware version 1.6: DS1338

The correct driver will be set during factory flashing by Tinkerforge.

The following constants are available for this function:

For rtcDriver:

hat_brick.RTCDriverPCF8523 = 0
hat_brick.RTCDriverDS1338 = 1

New in version 2.0.3 (Firmware).

func (*HATBrick) GetRTCDriver() (rtcDriver uint8, err error)¶

Returns:	rtcDriver – Type: uint8, Range: See constants err – Type: error

Returns the RTC driver as set by SetRTCDriver().

The following constants are available for this function:

For rtcDriver:

hat_brick.RTCDriverPCF8523 = 0
hat_brick.RTCDriverDS1338 = 1

New in version 2.0.3 (Firmware).

func (*HATBrick) GetSPITFPErrorCount() (errorCountAckChecksum uint32, errorCountMessageChecksum uint32, errorCountFrame uint32, errorCountOverflow uint32, err error)¶

Returns:	errorCountAckChecksum – Type: uint32, Range: [0 to 2³² - 1] errorCountMessageChecksum – Type: uint32, Range: [0 to 2³² - 1] errorCountFrame – Type: uint32, Range: [0 to 2³² - 1] errorCountOverflow – Type: uint32, Range: [0 to 2³² - 1] err – Type: error

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.

func (*HATBrick) SetStatusLEDConfig(config uint8) (err error)¶

Parameters:	config – Type: uint8, Range: See constants, Default: 3
Returns:	err – Type: error

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:

For config:

hat_brick.StatusLEDConfigOff = 0
hat_brick.StatusLEDConfigOn = 1
hat_brick.StatusLEDConfigShowHeartbeat = 2
hat_brick.StatusLEDConfigShowStatus = 3

func (*HATBrick) GetStatusLEDConfig() (config uint8, err error)¶

Returns:	config – Type: uint8, Range: See constants, Default: 3 err – Type: error

Returns the configuration as set by SetStatusLEDConfig()

The following constants are available for this function:

For config:

hat_brick.StatusLEDConfigOff = 0
hat_brick.StatusLEDConfigOn = 1
hat_brick.StatusLEDConfigShowHeartbeat = 2
hat_brick.StatusLEDConfigShowStatus = 3

func (*HATBrick) GetChipTemperature() (temperature int16, err error)¶

Returns:	temperature – Type: int16, Unit: 1 °C, Range: [-2¹⁵ to 2¹⁵ - 1] err – Type: error

Returns the temperature 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.

func (*HATBrick) Reset() (err error)¶

Returns:	err – Type: error

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!

func (*HATBrick) GetIdentity() (uid string, connectedUid string, position rune, hardwareVersion [3]uint8, firmwareVersion [3]uint8, deviceIdentifier uint16, err error)¶

Returns:

Returns:	uid – Type: string, Length: up to 8 connectedUid – Type: string, Length: up to 8 position – Type: rune, Range: ['i'] hardwareVersion – Type: [3]uint8 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] firmwareVersion – Type: [3]uint8 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] deviceIdentifier – Type: uint16, Range: [0 to 2¹⁶ - 1] err – Type: error

uid – Type: string, Length: up to 8
connectedUid – Type: string, Length: up to 8
position – Type: rune, Range: ['i']
hardwareVersion – Type: [3]uint8

0: major – Type: uint8, Range: [0 to 255]
1: minor – Type: uint8, Range: [0 to 255]
2: revision – Type: uint8, Range: [0 to 255]

firmwareVersion – Type: [3]uint8

0: major – Type: uint8, Range: [0 to 255]
1: minor – Type: uint8, Range: [0 to 255]
2: revision – Type: uint8, Range: [0 to 255]

deviceIdentifier – Type: uint16, Range: [0 to 2¹⁶ - 1]
err – Type: error

Returns the UID, the UID where the HAT is connected to (typically '0' as the HAT is the root device in the topology), the position, the hardware and firmware version as well as the device identifier.

The HAT (Zero) Brick is always at position 'i'.

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

Callback Configuration Functions¶

func (*HATBrick) SetVoltagesCallbackConfiguration(period uint32, valueHasToChange bool) (err error)¶

Parameters:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 valueHasToChange – Type: bool, Default: false
Returns:	err – Type: error

The period is the period with which the VoltagesCallback 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.

New in version 2.0.1 (Firmware).

func (*HATBrick) GetVoltagesCallbackConfiguration() (period uint32, valueHasToChange bool, err error)¶

Returns:	period – Type: uint32, Unit: 1 ms, Range: [0 to 2³² - 1], Default: 0 valueHasToChange – Type: bool, Default: false err – Type: error

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 with the corresponding Register*Callback function, which returns a unique callback ID. This ID can be used to deregister the callback later with the corresponding Deregister*Callback function.

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.

func (*HATBrick) RegisterVoltagesCallback(func(voltageUSB uint16, voltageDC uint16)) (registrationId uint64)¶

Callback Parameters:	voltageUSB – Type: uint16, Unit: 1 mV, Range: [0 to 2¹⁶ - 1] voltageDC – Type: uint16, Unit: 1 mV, Range: [0 to 2¹⁶ - 1]
Returns:	registrationId – Type: uint64

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

The callback parameters are the same as GetVoltages().

New in version 2.0.1 (Firmware).

Virtual Functions¶

Virtual functions don't communicate with the device itself, but operate only on the API bindings device object. They can be called without the corresponding IP Connection object being connected.

func (*HATBrick) GetAPIVersion() (apiVersion [3]uint8, err error)¶

Returns:	apiVersion – Type: [3]uint8 0: major – Type: uint8, Range: [0 to 255] 1: minor – Type: uint8, Range: [0 to 255] 2: revision – Type: uint8, Range: [0 to 255] err – Type: error

Returns the version of the API definition 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.

func (*HATBrick) GetResponseExpected(functionId uint8) (responseExpected bool, err error)¶

Parameters:	functionId – Type: uint8, Range: See constants
Returns:	responseExpected – Type: bool err – Type: error

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 sent and errors are silently ignored, because they cannot be detected.

The following constants are available for this function:

For functionId:

hat_brick.FunctionSetSleepMode = 1
hat_brick.FunctionSetBrickletPower = 3
hat_brick.FunctionSetVoltagesCallbackConfiguration = 6
hat_brick.FunctionSetRTCDriver = 9
hat_brick.FunctionSetWriteFirmwarePointer = 237
hat_brick.FunctionSetStatusLEDConfig = 239
hat_brick.FunctionReset = 243
hat_brick.FunctionWriteUID = 248

func (*HATBrick) SetResponseExpected(functionId uint8, responseExpected bool) (err error)¶

Parameters:	functionId – Type: uint8, Range: See constants responseExpected – Type: bool
Returns:	err – Type: error

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.

The following constants are available for this function:

For functionId:

hat_brick.FunctionSetSleepMode = 1
hat_brick.FunctionSetBrickletPower = 3
hat_brick.FunctionSetVoltagesCallbackConfiguration = 6
hat_brick.FunctionSetRTCDriver = 9
hat_brick.FunctionSetWriteFirmwarePointer = 237
hat_brick.FunctionSetStatusLEDConfig = 239
hat_brick.FunctionReset = 243
hat_brick.FunctionWriteUID = 248

func (*HATBrick) SetResponseExpectedAll(responseExpected bool) (err error)¶

Parameters:	responseExpected – Type: bool
Returns:	err – Type: error

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

Internal Functions¶

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

func (*HATBrick) SetBootloaderMode(mode uint8) (status uint8, err error)¶

Parameters:	mode – Type: uint8, Range: See constants
Returns:	status – Type: uint8, Range: See constants err – Type: error

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:

For mode:

hat_brick.BootloaderModeBootloader = 0
hat_brick.BootloaderModeFirmware = 1
hat_brick.BootloaderModeBootloaderWaitForReboot = 2
hat_brick.BootloaderModeFirmwareWaitForReboot = 3
hat_brick.BootloaderModeFirmwareWaitForEraseAndReboot = 4

For status:

hat_brick.BootloaderStatusOK = 0
hat_brick.BootloaderStatusInvalidMode = 1
hat_brick.BootloaderStatusNoChange = 2
hat_brick.BootloaderStatusEntryFunctionNotPresent = 3
hat_brick.BootloaderStatusDeviceIdentifierIncorrect = 4
hat_brick.BootloaderStatusCRCMismatch = 5

func (*HATBrick) GetBootloaderMode() (mode uint8, err error)¶

Returns:	mode – Type: uint8, Range: See constants err – Type: error

Returns the current bootloader mode, see SetBootloaderMode().

The following constants are available for this function:

For mode:

hat_brick.BootloaderModeBootloader = 0
hat_brick.BootloaderModeFirmware = 1
hat_brick.BootloaderModeBootloaderWaitForReboot = 2
hat_brick.BootloaderModeFirmwareWaitForReboot = 3
hat_brick.BootloaderModeFirmwareWaitForEraseAndReboot = 4

func (*HATBrick) SetWriteFirmwarePointer(pointer uint32) (err error)¶

Parameters:	pointer – Type: uint32, Unit: 1 B, Range: [0 to 2³² - 1]
Returns:	err – Type: error

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.

func (*HATBrick) WriteFirmware(data [64]uint8) (status uint8, err error)¶

Parameters:	data – Type: [64]uint8, Range: [0 to 255]
Returns:	status – Type: uint8, Range: [0 to 255] err – Type: error

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.

func (*HATBrick) WriteUID(uid uint32) (err error)¶

Parameters:	uid – Type: uint32, Range: [0 to 2³² - 1]
Returns:	err – Type: error

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.

func (*HATBrick) ReadUID() (uid uint32, err error)¶

Returns:	uid – Type: uint32, Range: [0 to 2³² - 1] err – Type: error

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

Constants¶

hat_brick.DeviceIdentifier¶

This constant is used to identify a HAT Brick.

The GetIdentity() function and the (*IPConnection) RegisterEnumerateCallback callback of the IPConnection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

hat_brick.DeviceDisplayName¶: This constant represents the human readable name of a HAT Brick.