Low-Level API Reference

Length in bytes of HID communcations.

MCP2221A default Vendor ID (VID), as per documentation.

MCP2221A default Product ID (PID), as per documentation.

Status flag for a response.

• Success: command succeded,
• I2CBusy:
• CommandNotSupported: Command not supported,
• COmmandNotAllowed: Command not allowed.

Chip security configuration option:

• PermanentlyLocked
• PasswordProtected
• Unsecured

Reference voltage configuration for DAC and ADC.

• Reference4p096: reference is 4.096V (only if VDD is above this voltage)
• Reference2p048: reference is 2.048V
• Reference1p024: reference is 1.024V

Reference voltage for DAC.

• SourceReferenceVRM: reference voltage is VRM
• SourceReferenceVDD: reference voltage is VDD

Cancellation status after a StatusSetParametersCommand:

• NoSpecialOperation cancel current I²C/SMBus transfer,
• MarkedForCancellation current transferm marked for cancellation, bus release will need some time,
• AlreadyIdle the I²C engine was already in Idle mode.

Communication speed status after a StatusSetParametersCommand:

• NoSetSpeed no new speed was issued,
• NewSpeedConsidered new speed is now considered,
• SpeedNotSet communication speed was not set.

I²C Frame mode. Writing and reading on the I²C bus is affected by this enumeration.

• I2CSingle
• I2CRepeatedStart
• I2CNoStop

Facility container for storing I²C addresses. Users generally should not care about this.

Fields

• address::UInt8

Enum to set the dedicated function of a GP pin.

• GPIOOperation
• DedicatedFunctionOperation
• AlternateFunction0
• AlternateFunction1
• AlternateFunction2

Enum to set the direction of a GP pin.

• GPIOInput
• GPIOOutput

Clock output duty cycle for GP1.

Clock output frequency for GP1.

Store the status of a GPIO.

Fields

• outputvalue::Bool: Logical value present at the output.

• direction::MCP2221Driver.GPDirection: GPIO direction.

• designation::MCP2221Driver.GPDesignation: GPIO designation. See GPDesignation for a list of available designation for each pin.

query(dev, command)

Blocking call to the device to send the command and receive the response if one is expected.

A generic response where only the response status is interesting.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

A generic response for commands that respond with a string.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• string::String: Response.

Poll the status of the device, and establish certain I²C bus parameters/conditions.

MCP2221Driver.StatusSetParametersCommand expects a MCP2221Driver.StatusSetParametersResponse response.

Fields

• cancelcurrent::Bool: Cancel current I²C/SMBus transfer

• divider::Int8: Set I²C/SMBus communication speed. If set to 0 don't act. Otherwise the new clock speed is 12 MHz/divider

Response for a StatusSetParametersCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• cancellationstatus::MCP2221Driver.CancellationStatus: Status of the cancellation request.

• speedstatus::MCP2221Driver.CommunicationSpeedStatus: Status of the new speed request.

• divider::UInt8: Divider value for the speed.

• requestedtransferlength::UInt16: Length of the requested I²C transfer.

• alreadytransferedlength::UInt16: Length of the already transfered I²C message.

• i2cbuffercounter::UInt8: Internal I²C data buffer counter.

• currentcommunicationspeeddividervalue::UInt8: Current communication speed divider value.

• currenti2ctimeoutvalue::UInt8: Current I²C timeout value.

• currenti2caddress::UInt16: Current I²C address.

• ackreceived::Bool: If ACK was received from client.

• sclvalue::UInt8: Current SCL line value.

• sdavalue::UInt8: Current SDA line value.

• interuptedgestate::Bool: Interrupt edge detector state.

• i2creadpendingvalue::UInt8: I²C read pending value.

• hardwareversion::VersionNumber: MCP2221 hardware version.

• firmwareversion::VersionNumber: MCP2221 firmware version.

• adcdatach0::UInt16: Channel 0 ADC value.

• adcdatach1::UInt16: Channel 1 ADC value.

• adcdatach2::UInt16: Channel 2 ADC value.

This command is used to force a Reset of the MCP2221A device. This command is useful when the Flash memory is updated with new data. The MCP2221A would need to be re-enumerated to see the new data.

MCP2221Driver.ResetChipCommand does not expects a response.

Main type for reading the flash memory.

Read chip settings from flash memory.

MCP2221Driver.ReadFlashDataChipSettingsCommand expects a MCP2221Driver.ReadFlashDataChipSettingsResponse response. See also WriteFlashDataChipSettingsCommand.

Response for a ReadFlashDataChipSettingsCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• cdcserialnumberenumerationenable::Bool: If true, the USB serial number will be used during the USB enumeration of the CDC interface.

• chipconfigurationsecurityoption::MCP2221Driver.ChipConfigurationSecurityOption: Chip configuration security option.

• clockoutputduty::MCP2221Driver.ClockOutputDutyCycle: If the GP pin is enabled for clock output operations, this is the duty cycle of the output.

• clockoutputdividervalue::MCP2221Driver.ClockOutputFrequency: If the GP pin is enabled for clock output operations, the divider value will be used on the 48MHz US internal clock and the divider output will be sent to this pin.

• dacreferencevoltage::MCP2221Driver.ReferenceVoltageOption: DAC reference voltage option.

• dacreferenceoption::MCP2221Driver.SourceReferenceOption: DAC reference option.

• powerupdacvalue::UInt8: Power-up DAC value.

• interruptdetectionnegativeedge::Bool: If true, the interrupt detection flag will be set when a negative edge occurs.

• interruptdetectionpositiveedge::Bool: If true, the interrupt detection flag will be set when a positive edge occurs.

• adcreferencevoltage::MCP2221Driver.ReferenceVoltageOption: ADC reference voltage.

• adcreferenceoption::MCP2221Driver.SourceReferenceOption: ADC reference option.

• vid::UInt16: USB VID value.

• pid::UInt16: USB PID value.

• usbpowerattributes::UInt8: USB power attribute as per USB 2.0 specification.

• usbrequestednumberofma::UInt8: USB requested number of mA(s) as per USB 2.0 specification.

Read GP settings from flash memory.

MCP2221Driver.ReadFlashDataGPSettingsCommand expects a MCP2221Driver.ReadFlashDataGPSettingsResponse response.

Response for a ReadFlashDataGPSettingsCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• gpio0powerupstatus::MCP2221Driver.GPIOStatus: GPIO0 status at power-up.

• gpio1powerupstatus::MCP2221Driver.GPIOStatus: GPIO1 status at power-up.

• gpio2powerupstatus::MCP2221Driver.GPIOStatus: GPIO2 status at power-up.

• gpio3powerupstatus::MCP2221Driver.GPIOStatus: GPIO3 status at power-up.

Read USB manufacturer string descriptor used during USB enumeration from flash memory.

MCP2221Driver.ReadFlashDataUSBManufacturerDescriptorStringCommand expects a MCP2221Driver.StringResponse response.

Read USB product string descriptor used during USB enumeration from flash memory.

MCP2221Driver.ReadFlashDataUSBProductDescriptorStringCommand expects a MCP2221Driver.StringResponse response.

Read USB serial number used during USB enumeration from flash memory.

MCP2221Driver.ReadFlashDataUSBSerialNumberDescriptorStringCommand expects a MCP2221Driver.StringResponse response.

Read chip factory serial number from flash memory. Cannot be changed.

MCP2221Driver.ReadFlashDataChipFactorySerialNumberCommand expects a MCP2221Driver.ReadFlashDataChipFactorySerialNumberResponse response.

Response for a ReadFlashDataChipFactorySerialNumberCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• number::Vector{UInt8}: Chip factory serial number, typically 8 bytes long.

Abstract supertype for all flash writing operations. Used internally because the MCP2221 actually have only one command divided in sub-commands for this.

Write chip settings into Flash memory.

MCP2221Driver.WriteFlashDataChipSettingsCommand expects a MCP2221Driver.GenericResponse response. See also ReadFlashDataChipSettingsCommand.

Fields

• cdcserialnumberenumerationenable::Bool: If true, the USB serial number will be used during the USB enumeration of the CDC interface.

• chipconfigurationsecurityoption::MCP2221Driver.ChipConfigurationSecurityOption: Chip configuration security option.

• clockoutputduty::MCP2221Driver.ClockOutputDutyCycle: If the GP pin is enabled for clock output operations, this is the duty cycle of the output.

• clockoutputdividervalue::MCP2221Driver.ClockOutputFrequency: If the GP pin is enabled for clock output operations, the divider value will be used on the 48MHz US internal clock and the divider output will be sent to this pin.

• dacreferencevoltage::MCP2221Driver.ReferenceVoltageOption: DAC reference voltage option.

• dacreferenceoption::MCP2221Driver.SourceReferenceOption: DAC reference option.

• powerupdacvalue::UInt8: Power-up DAC value.

• interruptdetectionnegativeedge::Bool: If true, the interrupt detection flag will be set when a negative edge occurs.

• interruptdetectionpositiveedge::Bool: If true, the interrupt detection flag will be set when a positive edge occurs.

• adcreferencevoltage::MCP2221Driver.ReferenceVoltageOption: ADC reference voltage.

• adcreferenceoption::MCP2221Driver.SourceReferenceOption: ADC reference option.

• vid::UInt16: USB VID value.

• pid::UInt16: USB PID value.

• usbpowerattributes::UInt8: USB power attribute as per USB 2.0 specification.

• usbrequestednumberofma::UInt8: USB requested number of mA(s) as per USB 2.0 specification.

• password::String: 8-byte password (for Flash modifications protection).

Write GP settings into Flash memory.

MCP2221Driver.WriteFlashDataGPSettingsCommand expects a MCP2221Driver.GenericResponse response. ReadFlashDataGPSettingsCommand.

Fields

• gpio0powerupstatus::MCP2221Driver.GPIOStatus: GPIO0 status at power-up.

• gpio1powerupstatus::MCP2221Driver.GPIOStatus: GPIO1 status at power-up.

• gpio2powerupstatus::MCP2221Driver.GPIOStatus: GPIO2 status at power-up.

• gpio3powerupstatus::MCP2221Driver.GPIOStatus: GPIO3 status at power-up.

Abstract super-type for all commands writing a string to flash memory. The subtypes are expected to expose a string attribute.

Write USB manufacturer descriptor string into Flash memory.

MCP2221Driver.WriteFlashDataUSBManufacturerDescriptorStringCommand expects a MCP2221Driver.GenericResponse response. See also ReadFlashDataUSBManufacturerDescriptorStringCommand.

Fields

• string::String

Write USB product descriptor string into Flash memory.

MCP2221Driver.WriteFlashDataUSBProductDescriptorStringCommand expects a MCP2221Driver.GenericResponse response. See also ReadFlashDataUSBProductDescriptorStringCommand.

Fields

• string::String

Write USB serial number descriptor string into Flash memory.

MCP2221Driver.WriteFlashDataUSBSerialNumberDescriptorStringCommand expects a MCP2221Driver.GenericResponse response. See also ReadFlashDataUSBSerialNumberDescriptorStringCommand.

Fields

• string::String

Send user-supplied password that will be compared to the one stored in the device's Flash when Flash updates are required and the Flash data are password-protected.

The password must be at most 8 bytes long. If your string contains characters more than one byte long, their LSB will be written first.

MCP2221Driver.SendFlashAccessPasswordCommand expects a MCP2221Driver.GenericResponse response.

Fields

• password::AbstractString: 8-bytes of password.

This command is used to al,er various run-time Chip settings. The altered settings reside in SRAM me,ory and they will not affect the Chip’s power-up/Reset default settings. These altered settings will be active until the next chip power-up/Reset.

MCP2221Driver.SetSRAMSettingsCommand expects a MCP2221Driver.GenericResponse response.

Fields

• clockoutputsettings::Union{Nothing, @NamedTuple{duty::MCP2221Driver.ClockOutputDutyCycle, dividervalue::MCP2221Driver.ClockOutputFrequency}}: If the GP pin is enabled for clock output operations, these are the duty cycle and the output frequency.

• dacsettings::Union{Nothing, @NamedTuple{referencevoltage::MCP2221Driver.ReferenceVoltageOption, referenceoption::MCP2221Driver.SourceReferenceOption}}: DAC settings.

• dacoutputvalue::Union{Nothing, UInt8}: DAC output value, only the 5 LSB are taken into account.

• adcsettings::Union{Nothing, @NamedTuple{referencevoltage::MCP2221Driver.ReferenceVoltageOption, referenceoption::MCP2221Driver.SourceReferenceOption}}: ADC settings.

• interruptdetectionpositiveedge::Union{Nothing, Bool}: If set to a boolean value, control wether interrupt detection will trigger on positive edges.

• interruptdetectionnegativeedge::Union{Nothing, Bool}: If set to a boolean value, control wether interrupt detection will trigger on negative edges.

• clearinterrupt::Bool: If set to true, clear the interrupt flag. Default is false.

• gpiosettings::Union{Nothing, @NamedTuple{gpio0::MCP2221Driver.GPIOStatus, gpio1::MCP2221Driver.GPIOStatus, gpio2::MCP2221Driver.GPIOStatus, gpio3::MCP2221Driver.GPIOStatus}}: If set, change GPIO settings. For more fine-grained control, see SetGPIOOutputValuesCommand.

This command is used to retrieve the run-time Chip and GP settings.

MCP2221Driver.GetSRAMSettingsCommand expects a MCP2221Driver.GetSRAMSettingsResponse response.

Response to a GetSRAMSettingsCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• lengthchipsettings::UInt8: Length in bytes of the SRAM Chip settings area.

• lengthgpsettings::UInt8: Length in bytes of the SRAM GP settings area.

• cdcserialnumberenumerationenable::Bool: If true, the USB serial number will be used during the USB enumeration of the CDC interface.

• chipconfigurationsecurityoption::MCP2221Driver.ChipConfigurationSecurityOption: Chip configuration security option.

• clockoutputduty::MCP2221Driver.ClockOutputDutyCycle: If the GP pin is enabled for clock output operations, this is the duty cycle of the output.

• clockoutputdividervalue::MCP2221Driver.ClockOutputFrequency: If the GP pin is enabled for clock output operations, the divider value will be used on the 48MHz US internal clock and the divider output will be sent to this pin.

• dacreferencevoltage::MCP2221Driver.ReferenceVoltageOption: DAC reference voltage option.

• dacreferenceoption::MCP2221Driver.SourceReferenceOption: DAC reference option.

• powerupdacvalue::UInt8: Power-up DAC value.

• interruptdetectionnegativeedge::Bool: If true, the interrupt detection flag will be set when a negative edge occurs.

• interruptdetectionpositiveedge::Bool: If true, the interrupt detection flag will be set when a positive edge occurs.

• adcreferencevoltage::MCP2221Driver.ReferenceVoltageOption: ADC reference voltage.

• adcreferenceoption::MCP2221Driver.SourceReferenceOption: ADC reference option.

• vid::UInt16: USB VID value.

• pid::UInt16: USB PID value.

• usbpowerattributes::UInt8: USB power attribute as per USB 2.0 specification.

• usbrequestednumberofma::UInt8: USB requested number of mA(s) as per USB 2.0 specification.

• password::String: Current Supplied Password (8 bytes).

• gpio0status::MCP2221Driver.GPIOStatus: GPIO0 status.

• gpio1status::MCP2221Driver.GPIOStatus: GPIO1 status.

• gpio2status::MCP2221Driver.GPIOStatus: GPIO2 status.

• gpio3status::MCP2221Driver.GPIOStatus: GPIO3 status.

Write data on the I²C bus. Depending on the chosen I2CFrameMode, the behavior will vary. The command has the following effects:

• Send the "Start" (I2CSingle, I2CNoStop) or "RepeatedStart" (I2CRepeatedStart) condition.
• Send the I²C client address and wait for the client to send an Acknowledge bit.
• The user data follow next. The I²C engine waits for the Acknowledge bit from the client.
• If the requested length is more than 60 bytes, subsequent user bytes will be sent on the bus.
• When the user data length reaches the requested length, the I²C engine will send the "Stop" condition on the bus, except when the mode is I2CNoStop.

Note that you can send data longer than 60 bytes by repeating the command, but this layer will not take care of that for you and will error if your data is longer than 60 bytes.

MCP2221Driver.I2CWriteDataCommand expects a MCP2221Driver.GenericResponse response.

Fields

• address::MCP2221Driver.I2CAddress

• writemode::MCP2221Driver.I2CFrameMode

• data::Vector{UInt8}

Read data from the I²C bus. Depending on the chosen I2CFrameMode, the behavior will vary. Note that the I2CNoStop mode is not supported. The command has the following effects:

• Send the "Start" (I2CSingle) or "RepeatedStart" (I2CRepeatedStart) condition.
• Send the I²C client address and wait for the client to send an Acknowledge bit.
• The user data follow next. The I²C engine sends the Acknowledge bit to the client.
• If the requested length is more than 60 bytes, subsequent user bytes will be read from the bus.
• When the user data length reaches the requested length, the I²C engine will send the "Stop" condition on the bus.

MCP2221Driver.I2CReadDataCommand expects a MCP2221Driver.GenericResponse response.

Fields

• address::MCP2221Driver.I2CAddress

• readmode::MCP2221Driver.I2CFrameMode

• length::UInt16

This command is used to read back the data from the I2C client device.

MCP2221Driver.GetI2CDataCommand expects a MCP2221Driver.GetI2CDataResponse response.

Response to a GetI2CDataCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• data::Vector{UInt8}

This command is used to change the GPIO output value for those GP pins assigned for GPIO operation (GPIO outputs).

MCP2221Driver.SetGPIOOutputValuesCommand expects a MCP2221Driver.GenericResponse response.

Fields

• gp0outputvalue::Union{Nothing, Bool}: GP0 output value, set to nothing to leave unchanged.

• gp0pindirection::Union{Nothing, Bool}: GP0 pin direction, set to nothing to leave unchanged, false for output, true for input.

• gp1outputvalue::Union{Nothing, Bool}: GP1 output value, set to nothing to leave unchanged.

• gp1pindirection::Union{Nothing, Bool}: GP1 pin direction, set to nothing to leave unchanged, false for output, true for input.

• gp2outputvalue::Union{Nothing, Bool}: GP2 output value, set to nothing to leave unchanged.

• gp2pindirection::Union{Nothing, Bool}: GP2 pin direction, set to nothing to leave unchanged, false for output, true for input.

• gp3outputvalue::Union{Nothing, Bool}: GP3 output value, set to nothing to leave unchanged.

• gp3pindirection::Union{Nothing, Bool}: GP3 pin direction, set to nothing to leave unchanged, false for output, true for input.

This command is used to retrieve the GPIO direction and pin value for those GP pins assigned for GPIO operation (GPIO inputs or outputs).

MCP2221Driver.GetGPIOValuesCommand expects a MCP2221Driver.GetGPIOValuesResponse response.

Response to a GetGPIOValuesCommand.

Fields

• status::MCP2221Driver.ResponseStatus: See ResponseStatus.

• gp0pinvalue::Union{Nothing, Bool}: GP0 logic pin value, or nothing if not set for GPIO operations.

• gp0directionvalue::Union{Nothing, Bool}: GP0 pin designation (false for output true for input), or nothing if not set for GPIO operations.

• gp1pinvalue::Union{Nothing, Bool}: GP1 logic pin value, or nothing if not set for GPIO operations.

• gp1directionvalue::Union{Nothing, Bool}: GP1 pin designation (false for output true for input), or nothing if not set for GPIO operations.

• gp2pinvalue::Union{Nothing, Bool}: GP2 logic pin value, or nothing if not set for GPIO operations.

• gp2directionvalue::Union{Nothing, Bool}: GP2 pin designation (false for output true for input), or nothing if not set for GPIO operations.

• gp3pinvalue::Union{Nothing, Bool}: GP3 logic pin value, or nothing if not set for GPIO operations.

• gp3directionvalue::Union{Nothing, Bool}: GP3 pin designation (false for output true for input), or nothing if not set for GPIO operations.