DAC8 Driver

Table of Contents

• DAC8 HAL Module Introduction
  • DAC8 HAL Module Features
  • DAC8 Hardware support details
• DAC8 HAL Module APIs Overview
• DAC8 HAL Module Operational Overview
  • DAC8 HAL Module Important Operational Notes and Limitations
    • DAC8 HAL Module Operational Notes
    • DAC8 HAL Module Limitations
• Including the DAC8 HAL Module in an Application
• Configuring the DAC8 HAL Module
  • DAC8 HAL Module Clock Configuration
  • DAC8 HAL Module Pin Configuration
• Using the DAC8 HAL Module in an Application

DAC8 HAL Module Introduction

The DAC8 HAL module provides a high-level API for digital-to-analog conversion applications and supports an 8-bit D/A converter (DAC8) peripheral on Synergy MCUs.

DAC8 HAL Module Features

• 8-Bit D/A Converter
• Left-Justified or Right-Justified Input Data Format
• Synchronization with the Analog-to-Digital Converter (ADC) module
• Multiple Operation Modes
  • Normal
  • Real-Time (Event Link)
  • Charge Pump Control

DAC8 HAL Module Block Diagram

DAC8 Hardware support details

The following hardware features are, or are not, supported by SSP for the DAC8.

Legend:

Symbol	Meaning
✓	Available (Tested)
⌧	Not Available (Not tested/not functional or both)
N/A	Not supported by MCU

MCU Group	8-Bit	2 Channels Output	3-Channel Output	Module-Stop Function	Event link function through ELC HAL driver *
S124	N/A	N/A	N/A	N/A	N/A
S128	✓	✓	✓	✓	✓
S1JA	✓	✓	N/A	✓	✓
S3A1	⌧	⌧	N/A	⌧	⌧
S3A3	✓	✓	N/A	✓	✓
S3A6	⌧	⌧	N/A	⌧	⌧
S3A7	N/A	N/A	N/A	N/A	N/A
S5D3	N/A	N/A	N/A	N/A	N/A
S5D5	N/A	N/A	N/A	N/A	N/A
S5D9	N/A	N/A	N/A	N/A	N/A
S7G2	N/A	N/A	N/A	N/A	N/A

• Note: The ELC event could be used instead of calling the DAC start() interface. This would have to be programmed by the user by setting up the link rather than using the ELC API. 

DAC8 HAL Module APIs Overview

The DAC8 HAL module defines APIs for opening, closing, starting, stopping and writing to the DAC. A complete list of the available APIs, an example API call and a short description of each can be found in the following table. A table of status return values follows the API summary table.

DAC8 HAL Module API Summary

Function Name	Example API Call and Description
open	g_dac8.p_api->open(g_dac8.p_ctrl, g_dac8.p_cfg Initial Configuration.
close	g_dac8.p_api->close(g_dac8.p_ctrl) Close the D/A Converter.
write	g_dac8.p_api->write(g_dac8.p_ctrl, val) Write Sample value to the D/A Converter.
start	g_dac8.p_api->start(g_dac8.p_ctrl) Start the D/A Converter if it has not been started yet.
stop	g_dac8.p_api->stop(g_dac8.p_ctrl) Stop the D/A Converter if the converter is running.
versionGet	g_dac8.p_api->versionGet(&version) Retrieve the API version with the version pointer.

Note

For more complete descriptions of operation and definitions for the function data structures, typedefs, defines, API data, API structures, and function variables, review the SSP User's Manual API References for the associated module.

Status Return Values

Name	Description
SSP_SUCCESS	API Call Successful.
SSP_ERR_HW_LOCKED	DAC resource is locked.
SSP_ERR_NOT_OPEN	Unit is not open.
SSP_ERR_ASSERTION	Wrong parameter.
SSP_ERR_IP_CHANNEL_NOT_PRESENT	Wrong channel selected.

Note

Lower-level drivers may return common error codes. Refer to the SSP User's Manual API References for the associated module for a definition of all relevant status return values.

DAC8 HAL Module Operational Overview

The DAC8 HAL module configures the 8-bit D/A converter (DAC8) to output one of 256 voltage levels between positive and negative reference voltages. The driver can be configured to accept the 8-bit output data in left‑or‑right‑justified format in a 16-bit input data. The driver supports two modes for the DAC.

• Normal mode – The D/A output is updated on writes to the data register.
• Real-Time (Event Link) – The D/A output is updated on an Event Link event. While in this mode the data register can be written at any time. An Event Link event triggers the start of conversion. Refer to the "ELC Interface" in the SSP User's Manual for more information.

To reduce the noise present in ADC readings the driver can configure synchronous anti-interference mode with the ADC module. This reduces conversion noise by disabling the DAC charge while the ADC is sampling. Check the hardware manual to determine if this feature is supported.

For operation at low AVCC voltage the driver can enable or disable the hardware charge pump.

Real-Time Mode

In real-time mode the output voltage is only changed on a signal from the ELC peripheral. Note when using real time mode the first call to dac_api_t::write() will set the initial output voltage.

As an illustration, the following code shows how to link the DAC8 output on channel 0 to the ELC software event and trigger the output to change.

/* Open DAC8 driver.  */
g_dac8_0.p_api->open(g_dac8_0.p_ctrl, &g_dac8_0.p_cfg);
/* Link DAC8 output 0 to software event 0.  
  In a real application, this feature would be used to link DAC8 output 
  to a hardware event. A software event is used here for simplicity. */
g_elc_on_elc.linkSet(ELC_PERIPHERAL_DA80, ELC_EVENT_ELC_SOFTWARE_EVENT_0);
/* Set initial output voltage, the output is immediately updated 
  because this is the first write since open. */
g_dac8_0.p_api->write(g_dac8_0.p_ctrl, initial_dac_value);
while (true) {
/* Set the next output value, the output voltage is not updated until 
      an ELC event occurs. */
g_dac8_0.p_api->write(g_dac8_0.p_ctrl, next_dac_value);
/* Generate software ELC event to update DAC output. */
g_elc_on_elc.softwareEventGenerate(ELC_SOFTWARE_EVENT_0);
R_BSP_SoftwareDelay(10, BSP_DELAY_UNITS_MILLISECONDS);
}

DAC8 HAL Module Important Operational Notes and Limitations

DAC8 HAL Module Operational Notes

• The DAC8 channel output is enabled during dac_api_t::start() and dac_api_t::write() and disabled during dac_api_t::stop() and dac_api_t::close().

DAC8 HAL Module Limitations

• The DAC8 driver does not configure the ELC peripheral for real-time mode. The user will need to configure the Event Link Controller in addition to enabling real-time mode in the DAC8 module.
• Refer to the most recent SSP Release Notes for any additional operational limitations for this module.

Including the DAC8 HAL Module in an Application

This section describes how to include the DAC8 HAL Module in an application using the SSP configurator.

Note

This section assumes you are familiar with creating a project, adding threads, adding a stack to a thread and configuring a block within the stack. If you are unfamiliar with any of these items, refer to the first few chapters of the SSP User's Manual to learn how to manage each of these important steps in creating SSP-based applications.

To add the DAC8 Driver to an application, simply add it to a thread using the stacks selection sequence given in the following table. (The default name for the DAC8 Driver is g_dac8_0. This name can be changed in the associated Properties window.)

DAC8 HAL Module Selection Sequence

Resource	ISDE Tab	Stacks Selection Sequence
g_dac8_0 DAC Driver on r_dac8	Threads	New Stack> Driver> Analog> DAC Driver on r_dac8

When the DAC8 Driver on r_dac8 is added to the thread stack as shown in the following figure, the configurator automatically adds any needed lower‑level modules. Any modules needing additional configuration information have the box text highlighted in Red. Modules with a Gray band are individual modules that stand alone. Modules with a Blue band are shared or common; they need only be added once and can be used by multiple stacks. Modules with a Pink band can require the selection of lower-level modules; these are either optional or recommended. (This is indicated in the block with the inclusion of this text.) If the addition of lower-level modules is required, the module description include Add in the text. Clicking on any Pink banded modules brings up the New icon and displays possible choices.

DAC8 HAL Module Stack

Configuring the DAC8 HAL Module

The DAC8 HAL Module must be configured by the user for the desired operation. The available configuration settings and defaults for all the user-accessible properties are given in the properties tab within the SSP configurator and are shown in the following tables for easy reference. Only properties that can be changed without causing conflicts are available for modification. Other properties are locked and not available for changes and are identified with a lock icon for the locked property in the Properties window in the ISDE. This approach simplifies the configuration process and makes it much less error-prone than previous manual approaches to configuration. The available configuration settings and defaults for all the user-accessible properties are given in the Properties tab within the SSP Configurator and are shown in the following tables for easy reference.

Note

You may want to open your ISDE, create the module and explore the property settings in parallel with looking over the following configuration table settings. This will help orient you and can be a useful 'hands-on' approach to learning the ins and outs of developing with SSP.

Configuration Settings for the DAC8 HAL Module on r_dac8

ISDE Property	Value	Description
Parameter Checking	BSP, Enabled, Disabled Default: BSP	Enable or disable the parameter error checking.
Name	g_dac8_0	Module name.
Channel	0	Channel selection.
Synchronize with ADC	Enabled, Disabled Default: Disabled	Choose whether to sync with the ADC module.
Data Format	Right Justified, Left Justified Default: Right Justified	Data format selection.
DAC Mode	Normal Mode, Real-time (Event Link) Mode Default: Normal Mode	DAC mode selection.
Charge Pump Enabled (Requires MOCO active)	Enabled, Disabled Default: Enabled	Enable or disable the charge pump.

Note

The example settings and defaults are for a project using the Synergy S7G2 MCU Group. Other MCUs may have different default values and available configuration settings.

DAC8 HAL Module Clock Configuration

The DAC8 HAL module does not require a specific clock configuration.

DAC8 HAL Module Pin Configuration

To use the DAC8 HAL module, the port pins for the channels receiving the analog input must be set as analog pins in the pin configurator. The following table illustrates the method for selecting the pins within the SSP configuration window and the subsequent table illustrates an example selection for the DAC pins:

Pin Selection for the DAC8 HAL Module on r_dac8

Resource	ISDE Tab	Pin selection Sequence
DAC8	Pins	Select Peripherals> Analog:DAC8> DAC80.

Note

The selection sequence assumes DAC80 is the desired hardware target for the driver.

Pin Configuration Settings for the DAC8 HAL Module on r_dac8

Property	Value	Description
Module Name	DAC80	DAC Peripheral Module.
Operation Mode	Enabled, Disabled Default: Enabled	DAC Peripheral operation mode.
DA0	None, DA0 Default: None	DAC Output Pin.
DA1	None, DA1 Default: None	DAC Output Pin.

Note

The example settings are for a project using the Synergy S7G2 MCU Group and the SK-S7G2 Kit. Other Synergy MCUs and Synergy Kits may have different available pin configuration settings.

Using the DAC8 HAL Module in an Application

The typical steps in using the DAC8 HAL module in an application are:

1. Initialize the DAC8 HAL module using the dac_api_t::open API.
2. Write a value using the dac_api_t::write API.
3. Start a conversion using the dac_api_t::start API.
4. Continue writing values as needed using the dac_api_t::write API.
5. Stop conversion using the dac_api_t::stop API.
6. Use the dac_api_t::close call to power down the peripheral.

These common steps are illustrated in a typical operational flow diagram in the following figure:

Flow Diagram of a Typical DAC8 HAL Module Application