Core independent ultrasonic proximity sensing peripheral
View Patent ↗A proximity sensing function is implemented using a collection of core independent peripherals (CIPs) in a microcontroller without software overhead to the central processor during operation thereof. A pulse width modulation (PWM) peripheral generates a high frequency drive signal that is on for a short duration to an ultrasonic transmitting transducer. An ultrasonic receiving transducer receives reflected ultrasonic pulses during an integration time window. The received pulses are detected and integrated into a voltage value. The integrated voltage value is compared to a prior voltage value average, and if different, generates a proximity sense signal of an object. Direction, distance and speed of the object may also be determined from the voltage values.
1. A method for ultrasonic proximity sensing, comprising the steps of:
providing a microcontroller having a central processor and memory, and a plurality of core independent peripherals (CIPs) comprising;
an analog-to-digital converter (ADC),
a configurable logic cell (CLC),
a data signal modulator (DSM),
a hardware limit timer (HLT),
a fixed voltage reference (FVR),
an operational amplifier (OPA),
a pulse width modulation generator (PWM), and
a timer counter register (TMR);
coupling an ultrasonic transmitting transducer to the DSM; and
coupling an ultrasonic receiving transducer to a receive OPA;
generating signals from the DSM to be transmitted as ultrasonic pulses from the ultrasonic transmitting transducer;
receiving reflected ultrasonic pulses with the ultrasonic receiving transducer and generating receive signals to the receive OPA;
detecting the received signals with an amplitude modulation detector;
integrating the detected received signals to a voltage value;
comparing the voltage value to a prior voltage value; and
generating a proximity sensed signal when the voltage value is different than the prior voltage value.
2. The method according to claim 1 , further comprising the step of integrating only the detected signals within an integration time window, wherein the integration time window represents a distance range of an object.
3. The method according to 2 , wherein the start and stop times of the integration time window are programmable.
4. The method according to claim 1 , further comprising the steps of:
integrating the detected signals within a plurality of different integration time windows to produce a plurality of voltage values representative of each of the different integration time windows;
comparing the plurality of voltage values to a plurality of prior voltage values representative of each of the different integration time windows; and
generating proximity sensed signals when any one or more of the plurality of voltage values is different than the respective ones of the plurality of prior voltage values representative of each of the different integration time windows.
5. The method according to claim 4 , further comprising the steps of:
determining which of the integration time windows have a proximity sensed signal;
determining in time order which of the proximity sensed signals are generated and the corresponding integration time windows thereof; and
comparing in time a first proximity sensed signal associated with a first integration time window to a second proximity sensed signal associated with a second integration time window, the first integration time window represents a proximity detection of an object at a closer location and the second integration time window represents a proximity detection of the object at a farther away location;
wherein
if the first proximity sensed signal occurs before the second proximity sensed signal then the object is moving away, and
if the second proximity sensed signal occurs before the first proximity sensed signal then the object is moving closer.
6. The method according to claim 5 , further comprising the step of determining a speed of the object from the time between the first and second proximity sensed signals.
7. The method according to claim 5 , further comprising the step of determining an approximate distance of the object from a proximity sensed signal associated with an integration time window representing the approximate distance of the object.
8. The method according to claim 1 , wherein the voltage value is sampled with the ADC and stored as a digital representation thereof.
9. An ultrasonic proximity sensing device, comprising:
a microcontroller comprising
a central processor and memory, and
a plurality of core independent peripherals (CIPs) comprising
an analog-to-digital converter (ADC),
a configurable logic cell (CLC),
a data signal modulator (DSM),
a hardware limit timer (HLT),
a fixed voltage reference (FVR),
an operational amplifier (OPA),
a programmable ramp generator (PRG),
a pulse width modulation generator (PWM), and
a timer counter register (TMR);
an ultrasonic transmitting transducer coupled to the DSM; and
an ultrasonic receiving transducer coupled to a receive OPA;
wherein the selected CIPs are configured to
generate signals to be transmitted as ultrasonic pulses from the ultrasonic transmitting transducer,
receive signals representing reflected ultrasonic pulses with the ultrasonic receiving transducer,
detect the received signals,
integrate the detected signals to voltage value,
sample the voltage value,
store the sampled voltage value as a present voltage value,
compare the present voltage value to a prior stored voltage value average, and
generate a proximity sensed signal when the present voltage value is different than the prior stored voltage value average.
10. The ultrasonic proximity sensing device according to claim 9 , wherein the CIPs generate the ultrasonic pulse signals, receive and detect the reflected ultrasonic pulse signals and stores the present voltage value without intervention from the central processor of the microcontroller.
11. The ultrasonic proximity sensing device according to claim 9 , wherein logic functions of the CLC are selected from the group consisting of a flip-flop, a NOR gate, an NAND gate, a XNOR gate, an AND gate, an OR gate, and a XOR gate.
12. The ultrasonic proximity sensing device according to claim 11 , wherein the CLC comprises at least two of the logic functions.
13. The ultrasonic proximity sensing device according to claim 12 , wherein:
an output from the DSM is coupled to the ultrasonic transmitting transducer;
the PWM is coupled to a first input of the DSM;
a first CLC is configured as a RS flip-flop and has an output coupled to a second input of the DSM; and
a first TMR has an input coupled to the output of the DSM, and an output coupled to a reset input of the first CLC;
wherein a start signal is coupled to a set input of the first CLC, whereby an ultrasonic pulse is generated each time the start signal is asserted and the ultrasonic pulse has a pulse duration determined by the first TMR.
14. The ultrasonic proximity sensing device according to claim 13 , further comprising:
a peak voltage detector coupled to an output of the receive OPA; and
a voltage integrator having a first input coupled to an output of the peak voltage detector and a second input coupled to a FVR, wherein when a voltage from the peak voltage detector is greater than a reference voltage from the FVR the voltage value increases.
15. The ultrasonic proximity sensing device according to claim 9 , wherein the ultrasonic pulses have a pulse duration of from about 40 to about 200 cycles at 40 kHz.
16. The ultrasonic proximity sensing device according to claim 9 , wherein the microcontroller is in a single integrated circuit package.
17. The ultrasonic proximity sensing device according to claim 9 , wherein the ultrasonic transmitting transducer is at least one ultrasonic transmitting transducer and the ultrasonic receiving transducer is a plurality of ultrasonic receiving transducers.
18. The ultrasonic proximity sensing device according to claim 17 , wherein the at least one ultrasonic transmitting transducer and the plurality of ultrasonic receiving transducers are arranged in an area for best ultrasonic proximity sensing operation.
19. The ultrasonic proximity sensing device according to claim 9 , wherein the microcontroller is reconfigured into an ultrasonic ranging device after sensing proximity of the at least one object.
20. The ultrasonic proximity sensing device according to claim 9 , wherein certain ones of the detected reflected ultrasonic pulses are integrated when occurring within an integration time window.
21. The ultrasonic proximity sensing device according to claim 20 , wherein start and stop times of the integration time window are programmable.
22. A microcontroller, comprising
a central processing unit and memory; and
configurable logic cell modules configured to provide
first and second RS-flip flops,
a first and second timer,
a data signal modulator (DSM),
an analog-to-digital converter (ADC),
a first operational amplifier,
a voltage reference module, and
a pulse width modulation (PWM) unit;
wherein the microcontroller is configured such that a PWM signal is fed to the DSM which generates an output PWM signal fed to an external pin and a clock input of the first timer whose output is fed to a reset input of the first SR-flip flop which receives a start signal at its set input and provides an output signal which is fed back to the DSM;
wherein the start signal is further fed to a reset input of the second SR-flip-flop whose output triggers the second timer controlling the ADC; and
wherein the first operational amplifier is configured as an integrator receiving an output signal from the ultrasonic receiver and a voltage reference from the voltage reference module.
23. The microcontroller according to claim 22 , wherein the output signal of the first SR-flip-flop is fed to a one-shot timer which sets the second SR flip-flop and holds and releases operation of the integrator.
24. The microcontroller according to claim 9 , further comprising a second operational amplifier configured to amplify an output signal from the ultrasonic receiver.