Device driver for Microchip MCP47xx DAC with I2C interface More...

Detailed Description

Device driver for Microchip MCP47xx DAC with I2C interface

Overview

The driver supports the different Microchip MCP47xx DAC variants.

Expander	Channels	Resolution
MCP4706	1	8-bit
MCP4716	1	10-bit
MCP4725	1	12-bit
MCP4726	1	12-bit
MCP4728	4	12-bit

Note

The following features of MCP47xx DAC devices are not supported at the moment:

configuring and reading address bits to/from EEPROM
writing DAC channel output values to the EEPROM
setting the UDAC bit and using the LDAC pin for MCP4728

Usage

Multiple MCP47xx DAC devices and different variants can be used at the same time.

The driver interface is kept as compatible as possible with the peripheral DAC interface. The only differences are that

functions have the prefix mcp47xx_ and
functions require an additional parameter, the pointer to the MCP47xx device of type mcp47xx_t.

Please refer the test application in tests/drivers/mcp47xx for an example on how to use the driver.

SAUL Capabilities

The driver provides SAUL capabilities that are compatible with SAUL actuators of type SAUL_ACT_DIMMER. Each MCP47xx channel can be mapped directly to SAUL by defining an according entry in MCP47XX_SAUL_DAC_PARAMS. Please refer file $RIOTBASE/drivers/mcp47xx/include/mcp47xx_params.h for an example.

 mcp47xx_saul_dac_params_t mcp47xx_saul_dac_params[] = {
     {
         .name = "DAC00",
         .dev = 0,
         .channel = 0,
         .initial = 32768,
     },
 };

For each DAC channel that should be used with SAUL, an entry with a name, the device, the channel, and the initial value has to be defined as shown above.

Using Multiple Devices

It is possible to used multiple devices and different variants of MCP47xx DAC devices at the same time. The application has to configure all devices by defining the configuration parameter set mcp47xx_params of type mcp47xx_params_t. As an example, the default configuration for one MCP4725 device is defined in drivers/mcp47xx/mcp47xx_params.h.

The application can override it by placing a file mcp47xx_params.h in the application directory $(APPDIR). For example, the definition of the configuration parameter set for the two devices (one MCP4725 and one MCP4728) could looks like:

 static const mcp47xx_params_t mcp47xx_params[] = {
     {
         .variant = MCP4725,
         .dev = I2C_DEV(0),
         .addr = MCP47XX_BASE_ADDR + 2,
         .gain = MCP47XX_GAIN_1X,
         .vref = MCP47XX_VDD,
         .pd_mode = MCP47XX_PD_LARGE,
     },
     {
         .variant = MCP4728,
         .dev = I2C_DEV(0),
         .addr = MCP47XX_BASE_ADDR + 3,
         .gain = MCP47XX_GAIN_2X,
         .vref = MCP47XX_VREF_INT,
         .pd_mode = MCP47XX_PD_LARGE,
     },
 };

Author: Gunar Schorcht gunar.nosp@m.@sch.nosp@m.orcht.nosp@m..net

Files
file	mcp47xx.h

file	mcp47xx_params.h
	Default configuration for Microchip MCP47xx DAC with I2C interface.

Data Structures
struct	mcp47xx_params_t
	MCP47xx device configuration parameters. More...

struct	mcp47xx_t
	MCP47xx device data structure type. More...

struct	mcp47xx_saul_dac_params_t
	MCP47xx configuration structure for mapping DAC channels to SAUL. More...

Enumerations
enum	mcp47xx_error_codes_t { MCP47XX_OK , MCP47XX_ERROR_I2C , MCP47XX_ERROR_NOT_AVAIL }
	MCP47xx driver error codes. More...

enum	mcp47xx_variant_t { MCP4706 , MCP4716 , MCP4725 , MCP4726 , MCP4728 }
	Supported MCP47xx variants. More...

enum	mcp47xx_gain_t { MCP47XX_GAIN_1X = 0 , MCP47XX_GAIN_2X = 1 }
	MCP47xx gain configuration type. More...

enum	mcp47xx_vref_t { MCP47XX_VREF_VDD = 0 , MCP47XX_VREF_INT = 1 , MCP47XX_VREF_PIN = 2 , MCP47XX_VREF_BUF = 3 }
	MCP47xx V_REF configuration type. More...

enum	mcp47xx_pd_mode_t { MCP47XX_NORMAL = 0 , MCP47XX_PD_SMALL = 1 , MCP47XX_PD_MEDIUM = 2 , MCP47XX_PD_LARGE = 3 }
	MCP47xx Power-down mode selection type. More...

Functions
int	mcp47xx_init (mcp47xx_t dev, const mcp47xx_params_t params)
	Initialize the MCP47xx DAC.

int	mcp47xx_dac_init (mcp47xx_t *dev, uint8_t chn)
	Initialize a MCP47xx DAC channel.

void	mcp47xx_dac_set (mcp47xx_t *dev, uint8_t chn, uint16_t value)
	Write a value to a MCP47xx DAC channel.

void	mcp47xx_dac_get (mcp47xx_t dev, uint8_t chn, uint16_t value)
	Get the current value of a MCP47xx DAC channel.

void	mcp47xx_dac_poweron (mcp47xx_t *dev, uint8_t chn)
	Enables the MCP47xx DAC device.

void	mcp47xx_dac_poweroff (mcp47xx_t *dev, uint8_t chn)
	Disables the MCP47xx DAC device.

uint8_t	mcp47xx_dac_channels (mcp47xx_t *dev)
	Returns the number of channels of MCP47xx DAC device.

MCP47xx I2C slave addresses
MCP47xx I2C slave addresses are defined as an offset to a base address, which depends on the expander used. The address offset is in the range of 0 to 7.
#define	MCP47XX_BASE_ADDR (0x60)
	MCP47xx I2C slave base address.

MCP47xx Channel number
#define	MCP4706_CHN_NUM (1)
	MCP4706 has 1 channel.

#define	MCP4716_CHN_NUM (1)
	MCP4716 has 1 channel.

#define	MCP4725_CHN_NUM (1)
	MCP4725 has 1 channel.

#define	MCP4726_CHN_NUM (1)
	MCP4726 has 1 channel.

#define	MCP4728_CHN_NUM (4)
	MCP4728 has 4 channels.

#define	MCP47XX_CHN_NUM_MAX (4)
	maximum number of channels

Macro Definition Documentation

◆ MCP4706_CHN_NUM

#define MCP4706_CHN_NUM (1)

MCP4706 has 1 channel.

Definition at line 140 of file mcp47xx.h.

◆ MCP4716_CHN_NUM

#define MCP4716_CHN_NUM (1)

MCP4716 has 1 channel.

Definition at line 141 of file mcp47xx.h.

◆ MCP4725_CHN_NUM

#define MCP4725_CHN_NUM (1)

MCP4725 has 1 channel.

Definition at line 142 of file mcp47xx.h.

◆ MCP4726_CHN_NUM

#define MCP4726_CHN_NUM (1)

MCP4726 has 1 channel.

Definition at line 143 of file mcp47xx.h.

◆ MCP4728_CHN_NUM

#define MCP4728_CHN_NUM (4)

MCP4728 has 4 channels.

Definition at line 144 of file mcp47xx.h.

◆ MCP47XX_BASE_ADDR

#define MCP47XX_BASE_ADDR (0x60)

MCP47xx I2C slave base address.

Addresses are then in the range from 0x60 to 0x67

Definition at line 131 of file mcp47xx.h.

◆ MCP47XX_CHN_NUM_MAX

#define MCP47XX_CHN_NUM_MAX (4)

maximum number of channels

Definition at line 145 of file mcp47xx.h.

Enumeration Type Documentation

◆ mcp47xx_error_codes_t

enum mcp47xx_error_codes_t

MCP47xx driver error codes.

Enumerator
MCP47XX_OK	success
MCP47XX_ERROR_I2C	I2C communication error.
MCP47XX_ERROR_NOT_AVAIL	device not available

Definition at line 150 of file mcp47xx.h.

◆ mcp47xx_gain_t

enum mcp47xx_gain_t

MCP47xx gain configuration type.

Note: Gains are not supported by MCP4725.

Enumerator
MCP47XX_GAIN_1X	Gain is 1.0, supported by all MCP47xx variants.
MCP47XX_GAIN_2X	Gain is 2.0, not supported by MCP4725.

Definition at line 175 of file mcp47xx.h.

◆ mcp47xx_pd_mode_t

enum mcp47xx_pd_mode_t

MCP47xx Power-down mode selection type.

Defines the possible power-down modes used for MCP47xx device configuration. The mode is used by function mcp47xx_dac_poweroff to set the DAC into the configured power-down mode.

Note: MCP47XX_NORMAL cannot be configured as power-down mode.

Enumerator
MCP47XX_NORMAL	Normal mode.
MCP47XX_PD_SMALL	Power down, small resistor 1 kOhm.
MCP47XX_PD_MEDIUM	Power down, medium resistor, 125 kOhm for MCP47x6, 100 kOhm otherwise.
MCP47XX_PD_LARGE	Power down, large resistor, 640 kOhm for MCP47x6, 125 kOhm otherwise.

Definition at line 201 of file mcp47xx.h.

◆ mcp47xx_variant_t

enum mcp47xx_variant_t

Supported MCP47xx variants.

It is used in configuration parameters to specify the MCP47xx expander used by device.

Enumerator
MCP4706	1 channel 8-bit DAC
MCP4716	1 channel 10-bit DAC
MCP4725	1 channel 12-bit DAC
MCP4726	1 channel 12-bit DAC
MCP4728	4 channel 12-bit DAC

Definition at line 162 of file mcp47xx.h.

◆ mcp47xx_vref_t

enum mcp47xx_vref_t

MCP47xx V_REF configuration type.

Note: Different MCP47xx variants allow different V_REF configurations

Enumerator
MCP47XX_VREF_VDD	V_REF = V_DD, supported by all MCP47xx.
MCP47XX_VREF_INT	V_REF = internal (2.048 V), MCP4728 only
MCP47XX_VREF_PIN	V_REF = VREF pin not buffered, MCP47x6 only.
MCP47XX_VREF_BUF	V_REF = VREF pin buffered, MCP47x6 only.

Definition at line 185 of file mcp47xx.h.

Function Documentation

◆ mcp47xx_dac_channels()

uint8_t mcp47xx_dac_channels ( mcp47xx_t * dev )

Returns the number of channels of MCP47xx DAC device.

This function returns the number of channels of the device MCP47xx DAC device.

Parameters

[in] dev descriptor of the MCP47xx DAC device

Return values

number of channels on success or 0 on error

◆ mcp47xx_dac_get()

void mcp47xx_dac_get	(	mcp47xx_t *	dev,
		uint8_t	chn,
		uint16_t *	value )

Get the current value of a MCP47xx DAC channel.

The value is always given as 16-bit value and is internally scaled to the actual resolution that the DAC unit provides, e.g., 12-bit.

Parameters

[in]	dev	descriptor of the MCP47xx DAC device
[in]	chn	channel to set
[out]	value	value to set line to

◆ mcp47xx_dac_init()

int mcp47xx_dac_init	(	mcp47xx_t *	dev,
		uint8_t	chn )

Initialize a MCP47xx DAC channel.

After the initialization, the DAC channel is active and its output is set to 0.

Parameters

[in]	dev	descriptor of the MCP47xx DAC device
[in]	chn	channel to initialize

Return values

MCP47XX_OK	on success
MCP47XX_ERROR_*	a negative error code on error, see mcp47xx_error_codes_t

◆ mcp47xx_dac_poweroff()

void mcp47xx_dac_poweroff	(	mcp47xx_t *	dev,
		uint8_t	chn )

Disables the MCP47xx DAC device.

MCP47xx is switched to the power-down mode configured by the configuration parameter mcp47xx_params_t::pd_mode. V_OUT is loaded with the configured resistor to ground. Most of the channel circuits are powered off.

Note: If MCP47XX_NORMAL is used as power-down mode, the DAC can't be powerd off.

Parameters

[in]	dev	descriptor of the MCP47xx DAC device
[in]	chn	channel to power on

◆ mcp47xx_dac_poweron()

void mcp47xx_dac_poweron	(	mcp47xx_t *	dev,
		uint8_t	chn )

Enables the MCP47xx DAC device.

MCP47xx is enabled and the output is set to the last set value.

Parameters

[in]	dev	descriptor of the MCP47xx DAC device
[in]	chn	channel to power on

◆ mcp47xx_dac_set()

void mcp47xx_dac_set	(	mcp47xx_t *	dev,
		uint8_t	chn,
		uint16_t	value )

Write a value to a MCP47xx DAC channel.

The value is always given as 16-bit value and is internally scaled to the actual resolution that the DAC unit provides, e.g., 12-bit. So to get the maximum output voltage, this function has to be called with value set to 65535 (UINT16_MAX).

Parameters

[in]	dev	descriptor of the MCP47xx DAC device
[in]	chn	channel to set
[in]	value	value to set line to

◆ mcp47xx_init()

int mcp47xx_init	(	mcp47xx_t *	dev,
		const mcp47xx_params_t *	params )

Initialize the MCP47xx DAC.

All expander pins are set to be input and are pulled up.

Parameters

[in]	dev	descriptor of the MCP47xx DAC device
[in]	params	configuration parameters, see mcp47xx_params_t

Return values

MCP47XX_OK	on success
MCP47XX_ERROR_*	a negative error code on error, see mcp47xx_error_codes_t

Detailed Description

Overview

Usage

SAUL Capabilities

Using Multiple Devices

Files

Data Structures

Enumerations

Functions

MCP47xx I2C slave addresses

MCP47xx Channel number

Macro Definition Documentation

◆ MCP4706_CHN_NUM

◆ MCP4716_CHN_NUM

◆ MCP4725_CHN_NUM

◆ MCP4726_CHN_NUM

◆ MCP4728_CHN_NUM

◆ MCP47XX_BASE_ADDR

◆ MCP47XX_CHN_NUM_MAX

Enumeration Type Documentation

◆ mcp47xx_error_codes_t

◆ mcp47xx_gain_t

◆ mcp47xx_pd_mode_t

◆ mcp47xx_variant_t

◆ mcp47xx_vref_t

Function Documentation

◆ mcp47xx_dac_channels()

◆ mcp47xx_dac_get()

◆ mcp47xx_dac_init()

◆ mcp47xx_dac_poweroff()

◆ mcp47xx_dac_poweron()

◆ mcp47xx_dac_set()

◆ mcp47xx_init()