DALI Click

How does it work?

DALI Click is based on the two PS2701-1 small outline couplers from Renesas. The DALI interface represents an international standardized protocol for intelligent lighting control. It offers a very flexible network routing topology, as all nodes can be daisy-chained, connected in a star topology, or any combination of these. The master and the slave nodes are connected to the DALI bus, where a single DALI network can control up to 64 lighting devices. Data between the host MCU and the devices are transferred over a two-wire bi-directional bus through an asynchronous, half-duplex serial protocol, regardless of polarity.

After optoisolation, the transmit circuit on DALI Click uses a FET, the BSP3185, to sink the total DALI power supply current so that the line can be pulled LOW with its capacitors limiting the rise/fall rates. The pulses are produced by not pulling the line LOW so that it goes HIGH due to the power supply. On the other hand, the receiving circuit allows a constant current in the range of voltages used for the high logic state representation. It should be noted that this circuit does not represent a current supply to the DALI bus.

According to the DALI standard, this Click board™ also has a built-in Graetz bridge rectifier on its DALI bus, which can be connected to the built-in screw terminal, marked as DALI regardless of signal polarity. After it has been rectified, the DALI TX and RX signals go through the fast optocouplers and remain galvanically isolated from the rest of the circuit. The TX signal is routed to the RST pin of the mikroBUS™ socket, while the RX signal, with its respective LED indicator, is routed over an onboard INT ICP jumper to the interrupt INT or input capture ICP (PWM) pins, with the INT pin as the default. The PHY SEL button, connected to the CS pin of the mikroBUS™ socket, can be used for the physical layer selection method documented in the Ed-1 version of the standard.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via an onboard 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 containing 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 on DALI 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	ICP	DALI RX
DALI TX	TX	2	RST	INT	15	INT	DALI RX
SPI Chip Select	PHY	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	NC
	NC	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

DALI Click electrical specifications