Kristil – Smart House – Technical Notes

This page is just a place to put random technical notes relating to the system originally installed by Smart House and later re-branded as Kristil. Most of this information relates to the system as installed between 1998 and about 2005. Much of this information is still valid.

Smart Switch

Early version switches used a OTP (one time programmable) MC68HC11E9CFN2 micro. This required a new chip installed to update the firmware. Later versions used the MC68HC11F1 with external FLASH and RAM memory; allowing firmware upgrades over the network if you had the right gear.

The smart switch configuration is stored in EEPROM memory within the HC11. Active status and control variables are in RAM.

  • Hold all 4 buttons and apply power to restore EEPROM default settings

The Triac-Modules (dimmers) are triac based therefore leading edge dimmers.  The communications with the switch is a simple clock-data serial interface.  It cannot be directly connected or interfaced to a PC.


The network is a simple full duplex RS485 operating at a non-standard baud rate.

This example network message ( 00-07-10-C4-02-6C-0E-57-00 ) is smart-switch #10 sending a 7 byte broadcast message to all on the network, that writes data 57 to address 6C0E (or 0E6C).  This is the current outside light level being sent to all switches on the network and repeats about every minute.

  • Packets must have the following format: T B F D . . . . . D C C
  • T = to address (00 = broadcast, FF = master #1, FE = none yet)
  • B = byte count (inc. T, B, F & D, but not C C)
  • F = from address
  • D = data bytes (12 bytes maximum)
  • C = 16 bit Check Sum (calculated as packets are transmitted and received)

Messages – Commands

Command – Address – Rx/Tx – Data bytes – Action/Comments


  • B0    NODE    RX    3    request send data block
  • C1    NODE    RX    ??    accept data block (inc address etc)
  • C2    NODE    RX    3    bit set, address, mask
  • C3    NODE    RX    3    bit clear, address, mask
  • C4    NODE    RX    3    byte save, address, mask
  • C5    NODE    RX    2    run code from address ??
  • C6    NODE    RX    3    turn circuit on
  • C7    NODE    RX    3    turn circuit off


  • D0    NODE    RX    0    request status
  • D2    NODE    TX    4    accept data (reply to D0)
  • D3    NODE    TX    8    accept data (reply to D1)


  • E0    NODE    RX    8    accept this full address ??
  • E1    NODE    RX    1    accept this node address ??


  • F0    00/NODE    RX    2    go quiet for ???? cycles
  • F1    NODE    RX    0    take possession of network token
  • F2    NODE    RX    0    surrender token

Sample messages recorded

00-07-10-C4-02-6C-35-7E-00 : light level ??

Output Modules

Originally based on HC11 and HC05.  The early development was done before flash micros were common.

The output module link is not really SPI.  The clock frequency can vary to some degree.  The original triac module has a HC05 micro with 4MHz resonator, handling 3 channels of real-time dimming as well as the control link.  So it’s written in assembly and every instruction is counted.  We have example driver routines here somewhere in HC11 and PIC-micro assembler.

The hardware driver is a simple low-current 5V clock and data; just needs real-world protection from spikes-noise etc.  Clock is from the master controller to the slave module.  Data is bi-directional, but almost always master to slave.  More than one slave can be connect to one master at the same time.  The protocol includes an address.

Triac – Dimmer Module

The standard 3-circuit triac module can operate in “smart mode” where it is commanded and dimmable, or in “dumb mode” where each of the three outputs simply follows one of the 3 inputs.  In smart mode 2 of the inputs operate as clock and data for the control interface.

The rated load current rating depends mostly on heat and cooling.  Each output is good for about 10A but the module as a whole should not exceed 8-10A to be long term reliable and safe.  They are triac outputs, so leading-edge dimming, which is not the best for dimming electronic transformers and can generate RF noise.

Relay Modules

This is a lot like the triac module but has relay contact outputs.  There can be problems with relay reliability when switching inductive loads like older fluorescent lamps.

There is also a relay module with 8 low-current contacts.  This was mostly used to drive alarm sirens, connect monitoring, gate and door control.