1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
// Example of blocking TSC (Touch Sensing Controller) that lights an LED when touch is detected.
//
// This example demonstrates:
// 1. Configuring a single TSC channel pin
// 2. Using the blocking TSC interface with polling
// 3. Waiting for acquisition completion using `poll_for_acquisition`
// 4. Reading touch values and controlling an LED based on the results
//
// Suggested physical setup on STM32F303ZE Nucleo board:
// - Connect a 1000pF capacitor between pin PA10 and GND. This is your sampling capacitor.
// - Connect one end of a 1K resistor to pin PA9 and leave the other end loose.
// The loose end will act as the touch sensor which will register your touch.
//
// The example uses two pins from Group 4 of the TSC:
// - PA10 as the sampling capacitor, TSC group 4 IO2 (D68 on the STM32F303ZE nucleo-board)
// - PA9 as the channel pin, TSC group 4 IO1 (D69 on the STM32F303ZE nucleo-board)
//
// The program continuously reads the touch sensor value:
// - It starts acquisition, waits for completion using `poll_for_acquisition`, and reads the value.
// - The LED is turned on when touch is detected (sensor value < 40).
// - Touch values are logged to the console.
//
// Troubleshooting:
// - If touch is not detected, try adjusting the SENSOR_THRESHOLD value.
// - Experiment with different values for ct_pulse_high_length, ct_pulse_low_length,
// pulse_generator_prescaler, max_count_value, and discharge_delay to optimize sensitivity.
//
// Note: Configuration values and sampling capacitor value have been determined experimentally.
// Optimal values may vary based on your specific hardware setup.
// Pins have been chosen for their convenient locations on the STM32F303ZE board. Refer to the
// official relevant STM32 datasheets and user nucleo-board user manuals to find suitable
// alternative pins.
#![no_std]
#![no_main]
use defmt::*;
use embassy_stm32::gpio::{Level, Output, Speed};
use embassy_stm32::tsc::{self, *};
use embassy_stm32::{mode, peripherals};
use embassy_time::Timer;
use {defmt_rtt as _, panic_probe as _};
const SENSOR_THRESHOLD: u16 = 25; // Adjust this value based on your setup
#[embassy_executor::main]
async fn main(_spawner: embassy_executor::Spawner) {
let device_config = embassy_stm32::Config::default();
let context = embassy_stm32::init(device_config);
let tsc_conf = Config {
ct_pulse_high_length: ChargeTransferPulseCycle::_4,
ct_pulse_low_length: ChargeTransferPulseCycle::_4,
spread_spectrum: false,
spread_spectrum_deviation: SSDeviation::new(2).unwrap(),
spread_spectrum_prescaler: false,
pulse_generator_prescaler: PGPrescalerDivider::_16,
max_count_value: MaxCount::_255,
io_default_mode: false,
synchro_pin_polarity: false,
acquisition_mode: false,
max_count_interrupt: false,
};
let mut g: PinGroupWithRoles<peripherals::TSC, G4> = PinGroupWithRoles::default();
// D68 on the STM32F303ZE nucleo-board
g.set_io2::<tsc::pin_roles::Sample>(context.PA10);
// D69 on the STM32F303ZE nucleo-board
let tsc_sensor = g.set_io1::<tsc::pin_roles::Channel>(context.PA9);
let pin_groups: PinGroups<peripherals::TSC> = PinGroups {
g4: Some(g.pin_group),
..Default::default()
};
let mut touch_controller = tsc::Tsc::new_blocking(context.TSC, pin_groups, tsc_conf).unwrap();
// Check if TSC is ready
if touch_controller.get_state() != State::Ready {
crate::panic!("TSC not ready!");
}
info!("TSC initialized successfully");
// LED2 on the STM32F303ZE nucleo-board
let mut led = Output::new(context.PB7, Level::High, Speed::Low);
// smaller sample capacitor discharge faster and can be used with shorter delay.
let discharge_delay = 5; // ms
// the interval at which the loop polls for new touch sensor values
let polling_interval = 100; // ms
info!("polling for touch");
loop {
touch_controller.set_active_channels_mask(tsc_sensor.pin.into());
touch_controller.start();
touch_controller.poll_for_acquisition();
touch_controller.discharge_io(true);
Timer::after_millis(discharge_delay).await;
match read_touch_value(&mut touch_controller, tsc_sensor.pin).await {
Some(v) => {
info!("sensor value {}", v);
if v < SENSOR_THRESHOLD {
led.set_high();
} else {
led.set_low();
}
}
None => led.set_low(),
}
Timer::after_millis(polling_interval).await;
}
}
const MAX_GROUP_STATUS_READ_ATTEMPTS: usize = 10;
// attempt to read group status and delay when still ongoing
async fn read_touch_value(
touch_controller: &mut tsc::Tsc<'_, peripherals::TSC, mode::Blocking>,
sensor_pin: tsc::IOPin,
) -> Option<u16> {
for _ in 0..MAX_GROUP_STATUS_READ_ATTEMPTS {
match touch_controller.group_get_status(sensor_pin.group()) {
GroupStatus::Complete => {
return Some(touch_controller.group_get_value(sensor_pin.group()));
}
GroupStatus::Ongoing => {
// if you end up here a lot, then you prob need to increase discharge_delay
// or consider changing the code to adjust the discharge_delay dynamically
info!("Acquisition still ongoing");
Timer::after_millis(1).await;
}
}
}
None
}
|
