Fiona Lin / Mbed OS cap_sense

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capsense.h@1:40e5ac1119a6, 2022-07-12 (annotated)

Committer:
fionalin
Date:
Tue Jul 12 13:02:25 2022 -0400
Revision:
1:40e5ac1119a6
Parent:
0:4e3ad938564e
Child:
2:d9745be6c253
updated to macro format

Who changed what in which revision?

UserRevisionLine numberNew contents of line
fionalin 0:4e3ad938564e 1 #pragma once
fionalin 0:4e3ad938564e 2
fionalin 0:4e3ad938564e 3 #include <mbed.h>
fionalin 0:4e3ad938564e 4
fionalin 1:40e5ac1119a6 5 /**
fionalin 1:40e5ac1119a6 6 * Capacitive-sensing module.
fionalin 1:40e5ac1119a6 7 *
fionalin 1:40e5ac1119a6 8 * A capacitive sensor needs to be enabled and disabled periodically.
fionalin 1:40e5ac1119a6 9 * When the capacitive sensor is enabled, the capacitor charges.
fionalin 1:40e5ac1119a6 10 * During this period, try_measure should be called as often as
fionalin 1:40e5ac1119a6 11 * possible. When try_measure returns true, the measurement is ready
fionalin 1:40e5ac1119a6 12 * to be read.
fionalin 1:40e5ac1119a6 13 *
fionalin 1:40e5ac1119a6 14 * At some point, toggle needs to be called again to disable the
fionalin 1:40e5ac1119a6 15 * capacitive sensor. This gives the capacitor time to discharge.
fionalin 1:40e5ac1119a6 16 * Make sure to wait a bit before toggling the sensor back on;
fionalin 1:40e5ac1119a6 17 * otherwise, the capacitor might have leftover charge.
fionalin 1:40e5ac1119a6 18 */
fionalin 0:4e3ad938564e 19 class CapSense {
fionalin 0:4e3ad938564e 20 public:
fionalin 0:4e3ad938564e 21 CapSense(PinName measure_pin, PinName square_pin);
fionalin 0:4e3ad938564e 22
fionalin 0:4e3ad938564e 23 bool toggle();
fionalin 0:4e3ad938564e 24 bool try_measure();
fionalin 0:4e3ad938564e 25 long read_measurement();
fionalin 0:4e3ad938564e 26
fionalin 0:4e3ad938564e 27 private:
fionalin 0:4e3ad938564e 28 DigitalOut square_wave;
fionalin 0:4e3ad938564e 29 DigitalIn cap_sense_measure;
fionalin 0:4e3ad938564e 30 Timer timer;
fionalin 0:4e3ad938564e 31 long last_measurement;
fionalin 0:4e3ad938564e 32 bool measured_this_cycle;
fionalin 0:4e3ad938564e 33 };