7.2.1 Sensor Node Group

qtm_acquisition_control_t

A top-level container for an acquisition group
Contains pointers to group and node memory containing configurations and run-time data


Structure	Contents
`qtm_acquisition_control_t`	`qtm_acq_node_group_config_t (*qtm_acq_node_group_config);`
	`qtm_acq_4p_saml10_config_t (*qtm_acq_node_config);`
	`qtm_acq_node_data_t (*qtm_acq_node_data);`

qtm_acq_node_group_config_t

Common parameters, applied to all sensor nodes in the group


Parameter	Size	Range/Options	Usage
`num_sensor_nodes`	16-bit	4 to 65532	The total number of sensor nodes configured in the group, for example, a number of 4P sets X4.
`acq_sensor_type`	8-bit	`NODE_MUTUAL_4P`	Parallel sets of 4 mutual capacitance sensor nodes. Each set contains 4x PTC X masks and 1x PTC Y masks for the measurement of XY capacitance.
`calib_option_select`	1 byte	Bits 3:0 Calibration type	Selects which parameter is auto-tuned for charge transfer.
		`CAL_AUTO_TUNE_NONE`	No auto-tune for charge transfer
		`CAL_AUTO_TUNE_RSEL`	Series resistor tuned to the largest value that allows full charge transfer
		`CAL_AUTO_TUNE_PRSC`	Prescaler tuned to the lowest (fastest) value that allows full charge transfer
		`CAL_AUTO_TUNE_CSD`	Charge share delay tuned to the lowest value that allows full charge transfer
		Bits 7:4 Calibration target	Target charge time for sensor capacitance.
		`CAL_CHRG_2TAU`	Sensor charged for 2 x Time constant
		`CAL_CHRG_3TAU`	Sensor charged for 3 x Time constant
		`CAL_CHRG_4TAU`	Sensor charged for 4 x Time constant
		`CAL_CHRG_5TAU`	Sensor charged for 5 x Time constant
`freq_option_select`	1 byte	`FREQ_SEL_0` to `FREQ_SEL_15`	`FREQ_SEL_0` to `FREQ_SEL_15` inserts a delay cycle between measurements during oversampling, where 0 is the shortest delay, 15 the longest
`freq_option_select`	1 byte	`FREQ_SEL_SPREAD`	`FREQ_SEL_SPREAD` varies this delay from 0 to 15 in a sawtooth manner during the oversampling set
`ptc_interrupt_priority`	1 byte	1 to 3	Arm® NVIC Interrupt priority
`wakeup_exp`*	1 byte	0 to 15	The Wake-up Exponent is the exponent for the power of two, representing the wake-up count in PTC core clocks
Note: * - Not available on all devices.

qtm_acq_saml10_node_config_t

Note: This data structure is the specific configuration for SAM L10 PTC hardware.


Parameter	Size	Range/Options	Usage
`node_xmask[4]`	4x4 bytes (16 bytes) 4x8* bytes (32 bytes) *AVR-DA	Array/bit field	Select X pin masks for `NODE_MUTUAL_4P`. Set the bit(s) at location(s) corresponding to X line number(s). For example: X0 only = `0b00000001` = `0x01` X0 and X2 = `0b00000101` = `0x05`
`node_ymask`	4 bytes 8* bytes *AVR-DA	(bit field)	Select Y pin mask. Set the bit(s) at location(s) corresponding to Y line number(s). For example: Y5 only = `0b00100000` = `0x20` Y1, Y2 and Y7 = `0b10000110` = `0x86`
`node_csd`	1 byte	For SAM L1x: 0 to 255 For ATtiny81x,161x,321x: 0 to 31	The number of delay cycles to ensure the charging of the sensor node capacitances Note: If auto-tune is enabled, this value is used for initial compensation capacitor calibration. Ensure it allows sufficient time to charge the sensor.
`node_rsel_prsc`	1 byte	Bits 7:4 = RSEL `RSEL_VAL_0` `RSEL_VAL_20` `RSEL_VAL_50` `RSEL_VAL_70`* `RSEL_VAL_80`* `RSEL_VAL_100` `RSEL_VAL_120`* `RSEL_VAL_200`	Internal Y line series resistor selection * May not be available for all devices AVR-DA: 70 kΩ, 80 kΩ, 120 kΩ, 200 kΩ
`node_rsel_prsc`	1 byte	Bits 3:0 = PRSC `PRSC_DIV_SEL_1` `PRSC_DIV_SEL_2` `PRSC_DIV_SEL_4` `PRSC_DIV_SEL_6`* `PRSC_DIV_SEL_8` `PRSC_DIV_SEL_12`* `PRSC_DIV_SEL_14`* `PRSC_DIV_SEL_16`	Clock Prescaler Acquisition clock is derived and scaled from CPU clock for AVR® devices. * May not be available for all devices. AVR-DA: 6 , 12, 14 The numbers correspond to the prescaler value.
`node_gain`	1 byte	Bits 7:4 = Analog Gain `GAIN_1` `GAIN_2` `GAIN_4` `GAIN_8` `GAIN_16`	Analog Gain Setting Integration capacitor adjusted to control integrator gain.
`node_gain`	1 byte	Bits 3:0 = Digital Gain `GAIN_1` `GAIN_2` `GAIN_4` `GAIN_8` `GAIN_16`	Digital Gain Setting The accumulated sum is scaled to Digital Gain.
`node_oversampling`	1 byte	`FILTER_LEVEL_1` `FILTER_LEVEL_2` `FILTER_LEVEL_4` `FILTER_LEVEL_8` `FILTER_LEVEL_16` `FILTER_LEVEL_32` `FILTER_LEVEL_64`	The number of samples to accumulate for each measurement. Note: Oversampling must be configured to be greater than or equal to Digital Gain for correct operation.

qtm_acq_node_data_t

Individual node run-time data (array)


Parameter	Size	Range/Options	Usage
`node_acq_status`	1 byte	Bit 7	`1` = `NODE_CAL_ERROR` The sensor node capacitance exceeds the maximum compensation capacitance supported.
		Bit 6	`1` = Charge transfer tuning complete
		Bit 5	`1` = Calibration state set
		Bit 4: Bit 2 (3 Bits) Node calibration state `NODE_MEASURE` `NODE_CC_CAL` `NODE_PRSC_CAL` `NODE_RSEL_CAL` `NODE_CSD_CAL`	Indicates whether calibration is ongoing and its current stage
		Bit 1: Calibration Request	Write a ‘`1`’ to trigger calibration sequence on this node. (Reset to ‘`0`’ by module once actioned.)
		Bit 0: Enabled	Write a ‘`1`’ to enable this node for measurement.
`node_acq_signals`	2 bytes	Most recent measurement for this sensor node.	This is a 16-bit unsigned value. Accumulated and scaled as per `node_oversampling` and `node_gain_digital` settings.
`node_comp_caps`	2 bytes	Hardware calibration data	Indicates tuning of the compensation circuit for this node

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