Output signal protocol
A signal encoding and decoding protocol to convey discrete sets of information combined in a single carrier signal is disclosed. The protocol uses modulation of both amplitude and pulse width to carry multiple sets of information. A first signal is pulse width modulated to encode a first data and a second signal is pulse amplitude modulated to encode a second data. The two modulated signals are combined to generate a carrier signal encoded with both the first and second data.
1. An apparatus comprising:
a first processor configured to generate a first signal including a modulated pulse width and first encoded data;
a second processor configured to generate a second signal including a modulated amplitude and second encoded data; and
an output controller configured to combine the first signal and the second signal to generate an output signal, wherein the pulse width of the output signal is indicative of the first data and the amplitude is indicative of the second data.
2. The apparatus of claim 1 wherein the output controller includes a multiplier configured to multiply the first signal and the second signal to generate the output signal.
3. The apparatus of claim 1 further comprising a decoder operable to decode the output signal to determine the first data and the second data.
4. The apparatus of claim 3 wherein the decoder comprises an analog-to-digital converter adapted to measure an amplitude level of the output signal after a rising edge.
5. The apparatus of claim 3 wherein the decoder comprises:
a capacitor, wherein the capacitor is charged over a time, T, and the amplitude is determined by dividing the charge of the capacitor, Q, by a duty cycle of the output signal; and
an analog-to-digital converter adapted to decode the amplitude to determine the first data.
6. The apparatus of claim 1 further comprising at least one sensing element operable to generate at least one of the first signal and the second signal.
7. The apparatus of claim 6 wherein the at least one sensing element comprises one or more of a magnetic field sensing element, an inductive sensing element, a resistive sensing element, an optical sensing element, a pressure sensing element, a motor control element, or a temperature sensing element.
8. The apparatus of claim 7 wherein the at least one sensing element comprises a magnetic field sensing element operable to generate the first signal, wherein the first signal is indicative of a magnetic field associated with an object.
9. The apparatus of claim 8 wherein the first data is one or more of flux density, angle, position, speed, or current.
10. The apparatus of claim 8 wherein the second data includes a direction of rotation of the object.
11. The apparatus of claim 1 wherein the second signal includes a diagnostic signal.
12. The apparatus of claim 11 further comprising a diagnostic circuit configured to generate the diagnostic signal.
13. A method of communicating an output signal, the method comprising:
generating one or more signals;
processing the one or more signals to generate a pulse width modulated (PWM) signal having a pulse width encoded with first data;
processing the one or more signals to generate a pulse amplitude modulated (PAM) signal having an amplitude encoded with second data; and
generating an output signal by combining the pulse width modulated signal and the pulse amplitude modulated signal, wherein the pulse width of the output signal is indicative of the first data and the amplitude is indicative of the second data.
14. The method of claim 13 further comprising multiplying the first signal and the second signal to generate the output signal.
15. The method of claim 13 wherein the one or more signals are generated by at least one sensing element.
16. The method of claim 15 wherein the at least one sensing element comprises one or more of a magnetic field sensing element, an inductive sensing element, a resistive sensing element, an optical sensing element, a pressure sensing element, a motor control element, or a temperature sensing element.
17. The method of claim 16 wherein the at least one sensing element comprises a magnetic field sensing element operable to generate the first signal, wherein the first signal is indicative of a magnetic field associated with an object.
18. The method of claim 13 further comprising:
decoding by a microcontroller the pulse width of the output signal to determine the first data; and
decoding by the microcontroller the amplitude of the output signal to determine the second data.
19. The method of claim 18 wherein decoding of the amplitude comprises measuring the amplitude level of the output signal after a rising edge.
20. A method comprising:
generating one or more signals, wherein at least one of the one or more signals is generated by a magnetic field sensing element and is indicative of a magnetic field associated with an object;
processing the one or more signals to generate a pulse width modulated (PWM) signal having a pulse width encoded with first data;
processing the one or more signals to generate a pulse amplitude modulated (PAM) signal having an amplitude encoded with second data; and
generating an output signal by combining the pulse width modulated signal and the pulse amplitude modulated signal.