38.7.14 Filter Control
| Symbol | Description | Symbol | Description | Symbol | Description |
|---|---|---|---|---|---|
| R | Readable bit | HC | Cleared by Hardware | (Grey cell) | Unimplemented |
| W | Writable bit | HS | Set by Hardware | X | Bit is unknown at Reset |
| K | Write to clear | S | Software settable bit | — | — |
| Name: | FLTCTRL |
| Offset: | 0x0C0 |
| Reset: | 0x00000000 |
| Property: | RW |
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| Access | |||||||||
| Reset |
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| Access | |||||||||
| Reset |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| FLTCHNID[3:0] | FLTEN | ||||||||
| Access | R/W | R/W | R/W | R/W | R/W | ||||
| Reset | 0 | 0 | 0 | 0 | 0 | ||||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| DATA16EN | FMODE | OVRSAM[2:0] | |||||||
| Access | R/W | R/W | R/W | R/W | R/W | ||||
| Reset | 0 | 0 | 0 | 0 | 0 | ||||
Bits 13:10 – FLTCHNID[3:0] Channel ID
Identifies which input channel, k , is to be filtered by the Digital Filter.
Note:
- This bit is Enabled Protected. (Writes are ignored when CTRLA.ENABLE = 1) returns a bus error.
Bit 8 – FLTEN Filter Enable
When set, this bit enables the Digital Filter to filter the output data generated by the ADC. The input channel to be filtered is determined by FLTCHNID.
Note:
- This bit is Enabled Protected: (Writes are ignored when CTRLA.ENABLE = 1) returns a bus error.
Bit 4 – DATA16EN 16bit Averaging Mode
Note:
- This bit is Enabled Protected: (Writes are ignored when CTRLA.ENABLE = 1) returns a bus error.
This bit is significant only if FMODE = 1 (Averaging Mode) and CHNCFG2.FRACTk= 1 (Fractional Output Mode, where k = FLTCHNID[3:0] is the chosen input for filtering) as follows:
| Value | Description |
|---|---|
| 0 | Only the first 12 bits are significant, followed by 4 zeros. |
| 1 | All 16 bits of the filter output data are significant |
Bit 3 – FMODE Filter Mode
Note:
- This bit is Enabled Protected: (Writes are ignored when CTRLA.ENABLE = 1) returns a bus error.
| Value | Description |
|---|---|
| 0 | Filtering in Oversampling Mode (power-up default) |
| 1 | Filtering in Averaging Mode |
Bits 2:0 – OVRSAM[2:0] Oversampling Ratio
Note:
- This bit is Enabled Protected: (Writes are ignored when CTRLA.ENABLE = 1) returns a bus error.
Determines the number of samples generated in the burst mode used for computing one single filter output value.
The OVRSAM encoding depends on the FMODE setting as follows:
If FMODE = 1 (Oversampling Mode) then OVRSAM is encoded as follows:
| Value | Descripton |
|---|---|
| 000 | 4 samples, shift sum 1-bit to right, output data is 13-bits |
| 001 | 16 samples, shift sum 2-bits to right, output data is 14-bits |
| 010 | 64 samples, shift sum 3-bits to right, output data is 15-bits |
| 011 | 256 samples, shift sum 4-bits to right, output data is 16-bits |
| 100 | 2 samples, shift sum 0-bits to right, output data is in 12.1 format |
| 101 | 8 samples, shift sum 1-bit to right, output data is in 13.1 format |
| 110 | 32 samples, shift sum 2-bits to right, output data is in 14.1 format |
| 111 | 128 samples, shift sum 3-bits to right, output data is in 15.1 format |
If FMODE=0 (Averaging Mode), then OVRSAM is encoded as follows:
| Value | Descripton |
|---|---|
| 000 | 2 samples to be averaged |
| 001 | 4 samples to be averaged |
| 010 | 8 samples to be averaged |
| 011 | 16 samples to be averaged |
| 100 | 32 samples to be averaged |
| 101 | 64 samples to be averaged |
| 110 | 128 samples to be averaged |
| 111 | 256 samples to be averaged |
| Value | Name | Description |
|---|---|---|
| 0 | 4_SAMPLES | (If FMODE is 0) 4 samples (shift sum 1 bit to right, output data is 13-bits) / (If FMODE is 1) 2 samples to be averaged |
| 1 | 16_SAMPLES | (If FMODE is 0) 16 samples (shift sum 2 bits to right, output data is 14-bits) / (If FMODE is 1) 4 samples to be averaged |
| 2 | 64_SAMPLES | (If FMODE is 0) 64 samples (shift sum 3 bits to right, output data is 15-bits) / (If FMODE is 1) 8 samples to be averaged |
| 3 | 256_SAMPLES | (If FMODE is 0) 256 samples (shift sum 4 bits to right, output data is 16-bits) / (If FMODE is 1) 16 samples to be averaged |
| 4 | 2_SAMPLES | (If FMODE is 0) 2 samples (shift sum 0 bits to right, output data is 12.1 format) / (If FMODE is 1) 32 samples to be averaged |
| 5 | 8_SAMPLES | (If FMODE is 0) 8 samples (shift sum 1 bit to right, output data is 13.1 format) / (If FMODE is 1) 64 samples to be averaged |
| 6 | 32_SAMPLES | (If FMODE is 0) 32 samples (shift sum 2 bits to right, output data is 14.1 format) / (If FMODE is 1) 128 samples to be averaged |
| 7 | 128_SAMPLES | (If FMODE is 0) 128 samples (shift sum 3 bits to right, output data is 15.1 format) / (If FMODE is 1) 256 samples to be averaged |