31.5.4 Control D
| Name: | CTRLD |
| Offset: | 0x03 |
| Reset: | 0x00 |
| Property: | - |
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| INITDLY[2:0] | ASDV | SAMPDLY[3:0] | |||||||
| Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | R/W | |
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Bits 7:5 – INITDLY[2:0] Initialization Delay
These bits define the initialization/start-up delay before the first sample when enabling the ADC or changing to an internal reference voltage. Setting this delay will ensure that the reference, MUXes, etc. are ready before starting the first conversion. The initialization delay will also take place when waking up from deep sleep to do a measurement.
The delay is expressed as a number of CLK_ADC cycles.
| Value | Name | Description |
|---|---|---|
| 0x0 | DLY0 | Delay 0 CLK_ADC cycles. |
| 0x1 | DLY16 | Delay 16 CLK_ADC cycles. |
| 0x2 | DLY32 | Delay 32 CLK_ADC cycles. |
| 0x3 | DLY64 | Delay 64 CLK_ADC cycles. |
| 0x4 | DLY128 | Delay 128 CLK_ADC cycles. |
| 0x5 | DLY256 | Delay 256 CLK_ADC cycles. |
| Other | - | Reserved |
Bit 4 – ASDV Automatic Sampling Delay Variation
Writing this bit to ’1’ enables automatic sampling delay variation between ADC conversions. The purpose of varying sampling instant is to randomize the sampling instant and thus avoid standing frequency components in the frequency spectrum. The value of the SAMPDLY bits is automatically incremented by one after each sample.
When the Automatic Sampling Delay Variation is enabled and the SAMPDLY value reaches 0xF, it wraps around to 0x0.| Value | Name | Description |
|---|---|---|
| 0 | ASVOFF | The Automatic Sampling Delay Variation is disabled. |
| 1 | ASVON | The Automatic Sampling Delay Variation is enabled. |
Bits 3:0 – SAMPDLY[3:0] Sampling Delay Selection
These bits define the delay between consecutive ADC samples. The programmable Sampling Delay allows modifying the sampling frequency during hardware accumulation, to suppress periodic noise sources that may otherwise disturb the sampling. The SAMPDLY field can be also modified automatically from one sampling cycle to another, by setting the ASDV bit. The delay is expressed as CLK_ADC cycles and is given directly by the bitfield setting. The sampling cap is kept open during the delay.