blueroomelectronics
Well-Known Member
I've not announced a new kit since the Junebug (I do have a new kit ready called Wasp but the documentation is incomplete)
I've always had a desire to build my own thermostat as I think it would be a practical and useful device for both experimenting and actual use as an HVAC controller.
Although I've called the design Cricket from the start this is a much more modern design and here's what I have followed hopefully by feedback and suggestions by you.
Eight character 14 segment LCD display with decimal points
PIC18F6390 LCD controller or 18F8490 (I may need the extra pins)
I2C temperature IC LM75A or equ.
I2C RTCC with battery backup or trickle charger eg: DS1340
5V Simple Switcher supply eg: LM2675
RS485 communications
ICD debug support
Questions... (feel free to comment on anything in the post)
How many relays? 3 seems enough for 1 Heat & 1 Cool
Switching relays (very low power consumption) vs standard?
How many buttons would be the minimum to run a thermostat?
iButton support?
User expansion? Analog / I2C / digital?
Wall mounting options? Case?
Would you like to build your own thermostat?
**broken link removed**
The expensive ~$300 Aprilaire RS422 thermostat with 6 relays and info display on top. No battery backup whatsoever.
I've always had a desire to build my own thermostat as I think it would be a practical and useful device for both experimenting and actual use as an HVAC controller.
Although I've called the design Cricket from the start this is a much more modern design and here's what I have followed hopefully by feedback and suggestions by you.
Eight character 14 segment LCD display with decimal points
PIC18F6390 LCD controller or 18F8490 (I may need the extra pins)
I2C temperature IC LM75A or equ.
I2C RTCC with battery backup or trickle charger eg: DS1340
5V Simple Switcher supply eg: LM2675
RS485 communications
ICD debug support
Questions... (feel free to comment on anything in the post)
How many relays? 3 seems enough for 1 Heat & 1 Cool
Switching relays (very low power consumption) vs standard?
How many buttons would be the minimum to run a thermostat?
iButton support?
User expansion? Analog / I2C / digital?
Wall mounting options? Case?
Would you like to build your own thermostat?
**broken link removed**
The expensive ~$300 Aprilaire RS422 thermostat with 6 relays and info display on top. No battery backup whatsoever.