HAL OPAMP How to Use

group OPAMP_How_To_Use

OPAMP peripheral main features

OPAMP instances

The C5 device integrates one operational amplifiers: OPAMP1

OPAMP configuration mode

The OPAMP provide(s) several exclusive configuration modes.

• Standalone mode

• Programmable Gain Amplifier (PGA) mode, with or without external filtering (A capacitor can be connected between OPAMP output and inverting input for filtering purpose, refer to reference manual)

• Follower mode

OPAMP power mode

Each OPAMP instance can be configured in normal-power or low-power mode.

OPAMP speed mode

Each OPAMP instance can be configured in normal speed or high speed.

OPAMP calibration feature

The OPAMP provide(s) calibration capabilities.

• Calibration aims at improving voltage offset accuracy

• The OPAMP uses either factory calibration settings or user defined calibration settings (i.e. trimming mode).

• The user trimming values can be figured out by calling calibration handled by HAL_OPAMP_Calibrate().

• HAL_OPAMP_Calibrate()

  • Run automatically the calibration.

  • Enables the user trimming mode.

  • Updates the trimming registers values with fresh calibration results. The user might store the calibration results for latter usage (for example, monitoring the trimming based on temperature).

• HAL_OPAMP_CalibrateParallel()

  • Run calibration in parallel for linked HAL OPAMP handles to speed up calibration processing time.

OPAMP configuration mode:

Standalone mode

• OPAMP input and output are not internally connected. User can implement any circuitry using external components.

Follower mode

• Inverting Input is connected internally, no external connection on inverting input.

Programmable Gain Amplifier (PGA) mode (Resistor feedback output)

• The OPAMP output(s) is internally connected to resistor feedback.

• OPAMP internal programmable gain is either x2, x4, x8 or x16. Two usages:

  • inverting output not used, only programmable gain.

  • inverting input used for external filtering coupled with programmable gain (ex: connected capacitor for low-pass filtering).

The OPAMPs inverting input

The OPAMPs inverting input can be selected according to the Reference Manual “OPAMP functional description” chapter.

The OPAMPs non-inverting input

The OPAMPs non-inverting input can be selected according to the Reference Manual “OPAMP functional description” chapter.

How to use HAL OPAMP module driver

The OPAMP HAL driver can be used as follows:

How to initialize the OPAMP low level resources:

• OPAMP bus clock must be enabled to get read and write access to OPAMP registers.

• Configure the OPAMP input pins and output pin in analog mode using HAL_GPIO_Init() to map the OPAMP output to the GPIO pin.

• Declare a hal_opamp_handle_t handle structure.

• Initialize OPAMP instance using HAL_OPAMP_Init().

• Configure the OPAMP instance with HAL_OPAMP_SetConfig() function.

• Select the inverting input and the non-inverting input using HAL_OPAMP_SetConfigInputConnection()

• By default factory trimming is set, else, call HAL_OPAMP_Calibrate() or HAL_OPAMP_SetConfigTrimming() functions to use “user trimming” mode with the user PMOS and NMOS trimming values.

How to start and stop the OPAMP instances:

• Start the OPAMP instance using HAL_OPAMP_Start() function.

• Stop the OPAMP instance using HAL_OPAMP_Stop() function.

Operational amplifier possible pin connections:

• Cf Reference Manual

Note

clock is enabled inside HAL_OPAMP_Init() whenever USE_HAL_OPAMP_CLK_ENABLE_MODEL is not set to HAL_CLK_ENABLE_NO.