Apparatus and method for controlling temperature on a cooking appliance
An apparatus and a method for measuring temperature in a cooking appliance, both of which utilize a circuit for reading an input from a thermal resistive device. By including a processor and an amplifier in the circuit, embodiments reduce the number of processor pins required to modify the amplified input arising from the amplifier. In one embodiment, the processor utilizes a single processor pin, through which is distributed a control output corresponding to the input and modifying the operating parameters of the amplifier.
1. A cooking appliance with a cavity heated by a heating element, said cooking appliance comprising:
a temperature sensor under constant voltage, the temperature sensor in communication with the cavity;
an amplification circuit coupled to the temperature sensor, the amplification circuit comprising an amplifier having a control input and for amplifying a first input from the temperature sensor to generate an amplifier output;
a voltage divider circuit coupled to the temperature sensor, the voltage divider circuit providing a course temperature output; and
a processor having a fine input pin connected to the amplifier output and a course input pin connected to the course temperature output, the processor having a control output pin coupled to the control input of the amplifier, wherein the first input is amplified by an amount corresponding to a control output conducted through the output pin from the processor.
2. A cooking appliance according to claim 1 , wherein the temperature sensor comprises a resistive thermal device.
3. A cooking appliance according to claim 1 , wherein the control output indicates a temperature band, and wherein the temperature band is selected from one of at least 8 temperature bands.
4. A cooking appliance according to claim 3 , wherein the temperature band is selected from an input respecting the course temperature output representing the temperature of the cavity.
5. A cooking appliance according to claim 1 , wherein the control output sets the gain and shift of the amplifier.
6. A cooking appliance according to claim 1 further comprising a digital-to-analog converter coupled to the output pin, wherein the control output is an analog.
7. A cooking appliance according to claim 6 , wherein the digital-to-analog converter is internal to the processor.
8. A cooking appliance according to claim 1 , wherein the number of output processor pins to generate the first input does not exceed three.
9. A method for monitoring temperature in a cavity of an oven, said method comprising:
generating, by an amplification circuit, a first input respecting the temperature of the cavity;
generating, by a voltage divider, a course input respecting a course temperature of the cavity;
selecting, by a processor, a temperature band by comparing the first input to the course input;
formulating a control output corresponding to the temperature band;
communicating, by the processor, the control output via a single output pin; and
generating, by the amplification circuit, a second input in response to the output.
10. A method according to claim 9 , further comprising converting the control output from digital to analog.
11. A method according to claim 9 , wherein the temperature band identifies a set of amplified parameters for the second input.
12. A method according to claim 11 , wherein the amplified parameters comprise one or more of gain and shift, and wherein the gain and shift are conveyed by the control output as an analog voltage.
13. A method according to claim 9 , wherein the temperature band selected from one of at least 8 temperature bands.
14. A method according to claim 9 , wherein the number of processor pins required to generate the second input does not exceed three pins.
15. A temperature control circuit, comprising:
a temperature sensor under constant voltage;
a voltage divider coupled to the temperature sensor;
an operational amplifier coupled to a first leg of the voltage divider; and
a processor coupled to a second leg of the voltage divider, wherein the processor has a fine input pin coupled to an output of the operational amplifier and a course input pin coupled to a second leg of the voltage divider and a control output pin coupled to the operational amplifier, and wherein the processor is operatively configured to generate a control output for input to the operational amplifier that identifies a temperature band respecting the operating parameters of the operational amplifier.
16. A temperature control circuit according to claim 15 , further comprising a digital-to-analog converter coupled to the control output pin.
17. A temperature control circuit according to claim 15 , wherein the operating parameters include gain and shift, and wherein the gain and shift are conveyed by the control output as an analog voltage.
18. A temperature control circuit according to claim 15 , wherein the number of processor pins required to generate an input from the operation amplifier does not exceed three.