DAC 6 Click

How does it work?

DAC 6 Click is based on the DAC104S085, 10-bit resolution micro-power QUAD digital-to-analog converter with rail-to-rail output, from Texas Instruments. The DAC104S085 is manufactured on a CMOS process with an architecture that consists of switches and resistor strings that are followed by an output buffer. The reference voltage is applied at the VREFIN pin and is shared by all four DAC outputs (A, B, C, and D). This string consists of 1024 equal valued resistors with a switch at each junction of two resistors, plus a switch to the ground. The code loaded into the DAC register determines which switch is closed, connecting the proper node to the amplifier.

The voltage reference pin of the DAC104S085 is not buffered, and because of that, it is recommended to drive the VREFIN pin by a voltage source with a low output impedance. This is accomplished using the MCP1501, a low drift bandgap-based voltage reference from Microchip capable of sinking and sourcing 20mA of current. The bandgap uses chopper-based amplifiers, effectively reducing the drift to zero. The reference voltage range which can be applied to the VREFIN pin is 1V to VCC (in this case 2.048V), providing the widest possible output dynamic range with a maximum output current of 11mA per channel.

The DAC 6 Click communicates with MCU using the 3-Wire SPI serial interface that is compatible with standard SPI, QSPI™, MICROWIRE™ and operates at clock rates up to 40 MHz. To use the full dynamic range of the DAC104S085, it is possible to connect the VREFIN pin to the supply voltage VCC. Because of its low power consumption, a reference source may be used as the reference input or the supply voltage which results in accuracy and stability. The reference voltage level can be selected by positioning the SMD jumper labeled as VREF SEL to an appropriate position, selecting between a value of 2.048V and the supply voltage VCC.

This Click Board™ uses the SPI communication interface with both 3.3V and 5V. The onboard SMD jumper labeled as VCC SEL allows voltage selection for interfacing with both 3.3V and 5V MCUs. More information about the DAC104S085’s functionality, electrical specifications, and typical performance can be found in the attached datasheet. However, the Click board™ comes equipped with a library that contains easy to use functions and a usage example that may be used as a reference for the development.

Specifications

Pinout diagram

This table shows how the pinout on DAC 6 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
	NC	2	RST	INT	15	NC
SPI Chip Select	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

DAC 6 Click electrical specifications

Software Support

We provide a library for the DAC 6 Click on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Library Description

This library holds functions that can be used to write data to the device’s input shift register, or to set operation mode output channel and level.

Key functions:

• void dac6_write_data ( uint16_t wr_data ) – Sends 16-bit data to the device’s input shift register.
• void dac6_set_output ( uint8_t chan, uint8_t op_mod, uint16_t set_out ) – Function is used to set operation mode output channel and level.

Examples description

The application is composed of three sections :

• System Initialization – Initializes GPIO, SPI and LOG structures.
• Application Initialization – Initalizes SPI driver.
• Application Task – (code snippet) This example shows capabilities of DAC 6 click by changeing output values from 0 to the maximum output range on all four channels. Output voltage is calculated by using the equation : Vout = Vrefin * (set_out / 4095).

void application_task ( )
{
    for ( n_cnt = 0; n_cnt < 4096; n_cnt += 315 )
    {
        v_out = dac6_set_output ( DAC6_CHANNEL_A, 
                                  DAC6_WRITE_ALL_AND_UPDATE, 
                                  DAC6_V_REF_2048, 
                                  n_cnt );
        
        FloatToStr( v_out, log_text );
        mikrobus_logWrite( " VOUT ~ ", _LOG_TEXT );
        mikrobus_logWrite( log_text, _LOG_TEXT );
        mikrobus_logWrite( " mV", _LOG_LINE );
        mikrobus_logWrite( "--------------------", _LOG_LINE );
        Delay_ms( 5000 );
    }
    
    Delay_ms( 5000 );
}

The full application code, and ready to use projects can be found on our LibStock page.

Other mikroE Libraries used in the example:

• SPI
• UART
• Conversions

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 click or RS232 click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

mikroSDK

This Click board™ is supported with mikroSDK – MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.