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RocNetNode Pi08 LEDs


The Pi08 is based on the PCA9622 16 bit I2C LED driver.

I2C Addressing

The final Pi08 will be addressable in the range from 0x60 to 0x6F for driving 256 separate LED outputs connected to one RocNetNode/Raspberry Pi.

Chip Mode

The PCA9622 must be programmed after every system power on.
RocNetNode will scan this I2C range at startup or after using the RocNetNode Dialog and will setup the found chips.

The following registers will be set automatically:

  • In MODE1 the SLEEP register must be set to normal mode. (To activate the PWM oscillator)
  • Register LEDOUT0…LEDOUT3 must be set to enable the LED driver outputs.

Connecting LEDs

The LED common is the anode(+)(long leg) on +5V J1 and J2 pin 1.

Output support

Parameter Description
Port type LED
Addressing FLAT from 1 to 256
Value The on PWM from 0 to 255
Parameter Off The off PWM from 0 to 255
Blink Supported with regarding the delay value.
Delay(Dimming) Used as increment. A value of zero will switch directly to on/off PWM.
A value of one ist the slowest dim, app. 10ms * (on-off) PWM. (Increasing the delay value every 10ms.)

Note: The dimming speed could be influenced by the number of LEDs which have to be set at the same time.

Signal support

This is both for simple and medium complex signals up to 8 LED and max. 10 aspects. For more complex signals the macro type should be used.
Only the RED address will be used as offset for all LEDs.

Parameter Description
Control Aspect numbers
Port type LED
Addressing FLAT from 1 to 256 - number of aspects
Delay(Dimming) Is set automatically set to 10 so the LEDs will slow dim on and off.
This value is fixed and cannot be changed in the signal properties.

Aspect Values

See: Aspect Values
The number of controlled LEDs will be calculated from the aspect values.



  • Bus 2: Node ID 2
  • Base address 5
  • Control: Aspect numbers
  • Port type: LED


  • Aspects: 3

Aspect values:

Aspect Value Hex LED address
0 1 0x0001 5
1 2 0x0002 6
2 1285 0x0505 5 + 7 (blink)

Aspect value examples

Value LEDs
0x0001 LED 1 on
0x0002 LED 2 on
0x0004 LED 3 on
0x0008 LED 4 on
0x0101 LED 1 blinking
0x0505 LED 1 and 3 blinking
0x0003 LED 2 and LED 1 on
0x0103 LED 2 on and LED 1 blinking
0xFFFF All LED's Off


There are 3 brightness modes available:

Mode Description Activation
Weather The brightness reported with the clock update events is used. Default. With a LED output on address 1001.
Day The brightness is set by output command. With a LED output on address 1002, the output value is used. (If zero: 255)
Night The brightness is set by output command. With a LED output on address 1003, the output value is used. (If zero: 100)

Macro support

The LED Type is also supported in the macro setup.

rocnet/rocnetnode-led-en.txt · Last modified: 2023/11/04 10:53 by rjversluis