I'm putting a new kit together called Ladybug. (yes my kits are named after critters)

On the drawing board is a kit designed for Home automation, HVAC / furnace / AC controller with Ethernet plus it's expandable.

Before it gets set in stone (PCB layout) I'd like your opinions on the feature set.

Standard peripherals (100% sure)
One Ethernet jack with magnetics
Four Panasonic JS1-5V Relays
Two opto isolated inputs HCPL-2630
SPI EEPROM / Flash upto 8Mb
At least one 8 pin I/O port EasyPIC compatable

Likely to be there (80%)
DE9-Male DCE RS232 with HW/SW UART (jumper selectable)
RS485 SW UART

On the fence (50% either way)
XBee / XBee Pro socket with HW/SW UART (jumper selectable)

Do we need them?
433MHz RF receiver (handy for digital thermometers)?
NO/C/NC or NO/C relay outputs?
32,768Hz watch crystal?

Gone
SD card socket.
iButton connector (just use an I/O port if you need it)
Temperature sensors (also can be added via DIY I/O expansion)

As always your opinions on this would be appreciated.

 

If it is for controlling a home temperature remotely, why do away with the temperature sensors?

Along the same lines with environment control, humidity is a nice measurement in winter time.

Add some sort of X10 interface, that will open a world of other (already existing) "add-ons".

 

Thanks for the feedback.

The reasons I'm holding off on an onboard temperature sensor are:

The Ladybug will probably be located in the deep dark recesses of your home IE: near the furnace, in the basement.
The Oregon Scientific THGR268 Temperature / Humidity sensor and transmitter (433Mhz)

(I suppose I could add a 1-wire (DS18B20) header)

A little history on me, several years ago I was working on a thermostat kit you could program yourself. Named it Cricket and have designed and built several prototypes.
Ultimately the Cricket kit may never exist because of inexpensive devices like the $30 THGR268

A THGR268
The Ladybug will have expansion connectors and possibly an 2x7 LCD header (no backlight)

X10 support would be possible via the RS232 connector using a CM11A (Personally I find the ancient X10 stuff very unreliable, your mileage may differ)

A 16F917 Cricket Thermostat prototype