Use Continuous Read Mode for ADC

[SodaWithoutSparkles]

Component name

adc

Link to component documentation on our website

https://esphome.io/components/sensor/adc/

Describe the enhancement

The ADC component only works by doing one-shot reads as shown here:

https://github.com/esphome/esphome/blob/12ba4b142e8dd2950e9406de2f8d378631772688/esphome/components/adc/adc_sensor.h#L9-L14

and here:

https://github.com/esphome/esphome/blob/12ba4b142e8dd2950e9406de2f8d378631772688/esphome/components/adc/adc_sensor_esp32.cpp#L146-L169

It is inefficient to keep calling one-shot reads again and again, especially when the attenuation is known, or we are sampling very frequently (>= 1 sample / second)

Use cases

This would make Analog Threshold Binary Sensor responds more quickly, and be more efficient.

For example, a resistor divider network can aggregate multiple 5V pins into 1 adc sensor.

D0 -> 4K7 -> C
D1 -> 5K6 -> C
D2 -> 6K8 -> C
D3 -> 10K -> C
C -> ADC
C-> 220-> GND

Table of possible voltages

D0	D1	D2	D3	Rc	delta v	V
0	0	0	1	10000	0	0.107632094
0	0	1	0	6800	0.049063	0.156695157
0	1	0	0	5600	0.032308	0.189003436
1	0	0	0	4700	0.034574	0.223577236
0	0	1	1	4047.619	0.034178	0.257754965
0	1	0	1	3589.744	0.030978	0.288733342
1	0	0	1	3197.279	0.03316	0.321893538
0	1	1	0	3070.968	0.012355	0.334248187
1	0	1	0	2779.13	0.032525	0.366772978
1	1	0	0	2555.34	0.029575	0.396347863
0	1	1	1	2349.457	0.031758	0.428106006
1	0	1	1	2174.741	0.031234	0.45933978
1	1	0	1	2035.261	0.028409	0.487748345
1	1	1	0	1857.368	0.041768	0.529516144
1	1	1	1	1566.425	0.086239	0.615754812

Anything else?

https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/adc_continuous.html

[github-actions[bot]]

🏷️ I've automatically added the component: adc label to help categorize this feature request.