DIGI POT 9 Click Board

Product Description

How Does The DIGI POT 9 Click Board™ Work?

The DIGI POT 9 Click Board™ is based on the AD5235, a digital potentiometer that operates as a proper variable resistor from Analog Devices. The resistor wiper position is determined by the RDAC register contents, that act as a scratchpad register, allowing unlimited changes of resistance settings. The scratchpad register can be programmed with any position setting using the standard SPI serial interface by loading the 24-bit data-word. The nominal resistance of the RDAC between terminal A and terminal B (RAB) is 250kΩ with 1024 positions (10-bit resolution).

The DIGI POT 9 Click Board™ communicates with MCU through a standard SPI interface and operates at clock rates up to 10MHz, supporting the two most common SPI modes, SPI Mode 0 and 3. In the format of the data-word, the first four bits are commands, the following four bits are addresses, and the last 16 bits are data. When a specified value is set, this value can be stored in a corresponding EEMEM register for user-defined information such as memory data for other components, look-up table, or system identification information. During subsequent power-ups, the wiper setting is automatically loaded to that value. The device performs the same electronic adjustment function as a mechanical potentiometer with enhanced resolution, solid-state reliability, and superior low-temperature coefficient performance.

An additional feature of this board represents optional write-protect and hardware override preset signals, routed to the PWM and RST pins of the mikroBUS™ socket, and labelled as WP and PR. Hardware override preset feature refreshes the scratchpad register with the current contents of the EEMEM register. Factory default loads midscale until EEMEM is loaded with a new user-set value. On the other hand, the write-protect signal disables any changes to the scratchpad register contents, except for the EEMEM setting. Therefore, write-protect can be used to provide a hardware EEMEM protection feature. Also, it uses a ready RDY pin, routed to the INT pin of the mikroBUS™ socket, used for EEMEM instruction completion indication.

The DIGI POT 9 Click Board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library that contains easy-to-use functions and an example code that can be used, as a reference, for further development.

SPECIFICATIONS

PINOUT DIAGRAM

This table shows how the pinout of the DIGI POT 9 Click Board™ 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	WP	Write Protect
Hardware Override Preset	PR	2	RST	INT	15	RDY	Data Ready
SPI Chip Select	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
SPI Data OUT	SDO	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

DIGI POT 9 CLICK ELECTRICAL SPECIFICATIONS

Software Support

 void application_task ( void )
 {
 for ( uint16_t cnt = DIGIPOT9_WIPER_ZERO_SCALE; cnt <= DIGIPOT9_WIPER_FULL_SCALE; cnt += 50 )
 {
 digipot9_set_wiper_1 ( &digipot9, cnt ); 
 digipot9_set_wiper_2 ( &digipot9, cnt ); 
 log_printf( &logger, " * Wipers position set to %u *rn", cnt ); 
 Delay_ms( 1000 ); 
 }
 }

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