43.7.4 ADC Control Register D
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: | CTRLD |
Offset: | 0x10 |
Reset: | 0x00000000 |
Property: | Write-Protected, Enable-Protected |
Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
VREFSEL[2:0] | WKUPCLKCNT[3:0] | ||||||||
Access | R/W | R/W | R/W | R/W | R/W | R/W | R/W | ||
Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
ANLEN | CHNEN | ||||||||
Access | R/W | R/W | |||||||
Reset | 0 | 0 |
Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
CTLCKDIV[5:0] | |||||||||
Access | R/W | R/W | R/W | R/W | R/W | R/W | |||
Reset | 0 | 0 | 0 | 0 | 0 | 0 |
Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
Access | |||||||||
Reset |
Bits 30:28 – VREFSEL[2:0] VREF Input Selection
VREFSEL[2:0] | ADREF+ | ADREF- |
---|---|---|
000 |
AVDD | AVSS |
001 |
External VREFH | AVSS |
010-111 |
Reserved | Reserved |
- This bit is Enabled Protected. Writes are ignored when CTRLA.ENABLE = 1 and return a bus error.
Bits 27:24 – WKUPCLKCNT[3:0] Wake-Up TAD Clock Count bits
These bits represent the number of ADC TAD clocks required to warm-up the ADC module before it can perform conversion. Although the clocks are specific to each ADC, the WKUPCLKCNT bit is common to all ADC modules.
1111 = 215 = 32,768 TAD clocks
* * *
* * *
0110 = 26 = 64 TAD clocks
0101 = 25 = 32 TAD clocks
0100 = 24 = 16 TAD clocks
0011 = 24 = 16 TAD clocks
0010 = 24 = 16 TAD clocks
0001 = 24 = 16 TAD clocks
0000 = 24 = 16 TAD clocks
- Minimum required ADC warm-up time, (i.e., WKUPCLKCNT), is 50 μs. (i.e., TAD * WKUPCLKCNT).
- TAD = [1 / ((GCLK_ADC
Freq / (CTRLD.CTLCKDIV+1)) / (2 * CORCTRL.ADCDIV)) ] or
(GCLK_ADC Period * (CTRLD.CTLCKDIV+1)) * (2 * ADCDIV).
- These bits are Enabled Protected. Writes are ignored when CTRLA.ENABLE = 1 and return a bus error.
Bit 20 – ANLEN Analog and Bias Circuitry Enable for the ADC Module
- The CALCTRL register must be initialized by the users software to the factory-provided values in the CAL OTP Register FCCFG65 before setting ANLEN=1.
- CTRLA.ANAEN=1 must be set prior to setting ANLEN=1.
- This bit is Enabled Protected. Writes are ignored when CTRLA.ENABLE = 1 and return a bus error.
Value | Description |
---|---|
0 | ADC Analog and bias circuitry powered down and clocks suspended. Analog logic power saving mode. |
1 | Analog and bias circuitry enabled. Once the analog and bias circuit is enabled CTRLA.ANLEN=1 and ANLEN, the ADC module needs a warm-up time, as defined by the WKUPCLKCNT<3:0> bits. |
Bit 16 – CHNEN ADC Module Digital Enable
- This bit is Enabled Protected. Writes are ignored when CTRLA.ENABLE = 1 and return a bus error.
- ANLEN qualifies CHNEN: If ANLEN =0, then digital logic is also disabled.
Value | Description |
---|---|
0 | ADC digital logic disabled. No trigger, sample or conversion events will be processed. (power-saving mode with fast 2 TAD clock wakeup provided ANLEN = 1). |
1 | ADC digital logic enabled (required for active operation). |
Bits 13:8 – CTLCKDIV[5:0] A/D Clock Source to Control Clock Divider
The CTLCKDIV bit field divides the GCLK_ADC input clock into the ADC Module control clock CTL_CLK scaled by CTRLD.CTLCKDIV with period TQ.
Value | Description |
---|---|
111111 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 64·TGCLK_ADCx = TQ |
111110 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 63·TGCLK_ADCx = TQ |
... | ... |
000100 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 5·TGCLK_ADCx = TQ |
000011 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 4·TGCLK_ADCx = TQ |
000010 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 3·TGCLK_ADCx = TQ |
000001 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 2·TGCLK_ADCx = TQ |
000000 | TGCLK_ADCx·(CTLCKDIV[5:0]+1) = 1·TGCLK_ADCx = TQ |