AVR wireless dimmer Project circuit schematic with explanation

AVR wireless dimmer Project
At first we have to modify the layout of the old Avr dimmer. I don't think the RS232 interface will be used much when we have the wireless option available, so all the parts for the RS232 will have to go, the other thing that we don't really need anymore is the crystal with the 2 capacitors, because the ATtiny2313 has a build in RC clock of 4 and 8 Mhz which is more than sufficient. One more thing that could go is the infrared receiver, but this doesn't take much room on the circuit board so I will leave it on for the moment. The last thing we need to change is the power supply. The iDwaRF module needs between 2.7 to 3.6 Volts. The ATTiny2313 will run on a voltage between 2.7 to 5.5 volts and the infrared receiver needs 2,7 to 5,5 Volts if we use the TSOP 31236. So if we decide on a power supply of 3.3 Volts all the components will be happy.

Changing the voltage from 5 to 3.3 Volts sounds easier then it turned out to be. Negative regulators of -3.3 Volt are rare and if that is not all the Wireless module seems to have a peak current of more than 60 mA. Our old design could only supply an average of 20 mA. Also I want the dimmer to be power efficient, since I might end up with 10 or more dimmers, regulating everything in the house. So I am thinking of a switching regulator. This way we have a very efficient power supply that can temperarely supply higher currents. More will follow. This will need some testing.

At first we have to modify the layout of the old Avr dimmer. I don't think the RS232 interface will be used much when we have the wireless option available, so all the parts for the RS232 will have to go, the other thing that we don't really need anymore is the crystal with the 2 capacitors, because the ATtiny2313 has a build in RC clock of 4 and 8 Mhz which is more than sufficient. One more thing that could go is the infrared receiver, but this doesn't take much room on the circuit board so I will leave it on for the moment. The last thing we need to change is the power supply. The iDwaRF module needs between 2.7 to 3.6 Volts. The ATTiny2313 will run on a voltage between 2.7 to 5.5 volts and the infrared receiver needs 2,7 to 5,5 Volts if we use the TSOP 31236. So if we decide on a power supply of 3.3 Volts all the components will be happy.

Changing the voltage from 5 to 3.3 Volts sounds easier then it turned out to be. Negative regulators of -3.3 Volt are rare and if that is not all the Wireless module seems to have a peak current of more than 60 mA. Our old design could only supply an average of 20 mA. Also I want the dimmer to be power efficient, since I might end up with 10 or more dimmers, regulating everything in the house. So I am thinking of a switching regulator. This way we have a very efficient power supply that can temperarely supply higher currents. More will follow. This will need some testing.




http://domotica.homeip.net/dimmer3.html