#include <cfg/cs_Boards.h>
#include <cfg/cs_DeviceTypes.h>

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Functions
void	asACR01B10D (boards_config_t *config)
	The ACR01B10D is also known as the Crownstone Built-in One. More...

Function Documentation

◆ asACR01B10D()

void asACR01B10D ( boards_config_t * config )

The ACR01B10D is also known as the Crownstone Built-in One.

It comes with version v20 or the v25, but they are similar from a board configuration perspective.

The PWM enable pin might not be connected on the v20, but it is fine to be set nevertheless.

Reference voltage

The reference voltage can be measured on pin P0.02 or (AIN0).
It is created by a ADR280-1V2, which provides a stable 1.2V.

Measure current

There are three possible gains to measure current. Mainly the lowest gain is used.
There is a zero reference for the current (and voltage) and measures therefore differential.

Measure voltage

This built-in has an offset as additional input for the ADC. It can do differential measurements.
The ADC is configured with a range of -1.8V to 1.8V.
Said otherwise, the ADC is configured with 1/3 gain.
The voltage divider (R12/R13) centers at 3.3V/2 through two identical 68k resistors.
The equivalent parallel resistor is 34k.
The opamp gain becomes 34k/10.3M = 0.00330 (or 302.94x when inverted).
If we divide 3.6V over 4096-1 we have 0.87912 mV per interval.
The voltage multiplier of 0.00087912 * 302.94 = 0.26632.
The difference between 3.3V/2=1.65V and 1.2V = 0.45V.
That means there will be an offset of 450 / 0.87912 = 512. The voltageZero value. See: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fsaadc.html&cp=4_0_0_5_22_2&anchor=saadc_digital_output

TODO: Explain how it relates to: RESULT = (V(P) – V(N)) * (GAIN/REFERENCE) * 2^(RESOLUTION - m)

Temperature is set according to T_0 = 25 (room temperature) R_0 = 10000 (from datasheet, 10k at 25 degrees Celcius) B_ntc = 3434 K (from datasheet of NCP15XH103J03RC at 25-85 degrees Celcius) B_ntc = 3380 K (if we assume it to stay cold at for 25-50 degrees Celcius) B_ntc = 3455 K (if we assume it to become hot at 25-100 degrees Celcius) R_18 = 18000 R_ntc = R_0 * exp(B_ntc * (1/(T+273.15) - 1/(T_0+273.15))) V_temp = 3.3 * R_ntc/(R_22+R_ntc) See https://en.wikipedia.org/wiki/Thermistor#B_or_%CE%B2_parameter_equation.

We want to trigger between 76 < T < 82 degrees Celcius.

T	R_ntc	V_temp	B_ntc
25	10000	1.32

| 76 | 1859 | 0.3090 | 3434 | <- TODO: should be the used value | 82 | 1575 | 0.2655 | 3434 | <- TODO: should be the used value | 90 | 1256 | 0.2153 | 3455 |

Hence, 0.3135 < V_temp < 0.3639 in an inverted fashion (higher voltage means cooler).

Extras

There's a pin which can be used to measure the 15V supply. It has a 324/80.6 voltage divider.
It should be visible as a steady 15V * 80.6/(80.6+324) = 2.99V input on P0.05.
The TX power is with -20 higher for the built-ins than for the plugs.

Functions

Function Documentation

◆ asACR01B10D()