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The Amphenol ChipCap 2 is a capacitive polymer humidity and temperature sensor with an integrated EEPROM and minimum/maximum humidity alarms. All device variants offer an I2C interface and depending on the part number, two different output modes: - CC2D: digital output - CC2A: analog (PDM) output This driver adds support for the digital variant (CC2D part numbers), which includes the following part numbers: - non-sleep measurement mode (CC2D23, CC2D25, CC2D33, CC2D35) - sleep measurement mode (CC2D23S, CC2D25S, CC2D33S, CC2D35S) The Chipcap 2 EEPROM can be accessed to configure a series of parameters like the minimum/maximum humidity alarm threshold and hysteresis. The EEPROM is only accessible in the command window after a power-on reset. The default window lasts 10 ms if no Start_CM command is sent. After the command window is finished (either after the mentioned timeout of after a Start_NOM command is sent), the device enters the normal operation mode and makes a first measurement automatically. Unfortunately, the device does not provide any hardware or software reset and therefore the driver must trigger power cycles to enter the command mode. A dedicated, external regulator is required for that. This driver keeps the device off until a measurement or access to the EEPROM is required, making use of the first automatic measurement to avoid different code paths for sleep and non-sleep devices. The minimum and maximum humidity alarms are configured with two registers per alarm: one stores the alarm threshold and the other one keeps the value that turns off the alarm. The alarm signals are only updated when a measurement is carried out. Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com> Link: https://lore.kernel.org/r/20240130-topic-chipcap2-v6-5-260bea05cf9b@gmail.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Linux kernel
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