Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet
Product codes
ATSAMD21-XPRO
172
Atmel | SMART SAM D21 [DATASHEET]
Atmel-42181C–SAM-D21_Datasheet–07/2014
Notes: 1. Number of cycles for the start-up counter
2. Number of cycles for the synchronization delay, before PCLKSR.XOSCRDY is set.
3. Actual start-up time is n OSCULP32K cycles + 3 XOSC cycles, but given the time neglects the 3 XOSC
3. Actual start-up time is n OSCULP32K cycles + 3 XOSC cycles, but given the time neglects the 3 XOSC
cycles.
z
Bit 11 – AMPGC: Automatic Amplitude Gain Control
0: The automatic amplitude gain control is disabled.
1: The automatic amplitude gain control is enabled. Amplitude gain will be automatically adjusted during Crystal
Oscillator operation.
0: The automatic amplitude gain control is disabled.
1: The automatic amplitude gain control is enabled. Amplitude gain will be automatically adjusted during Crystal
Oscillator operation.
z
Bits 10:8 – GAIN[2:0]: Oscillator Gain
These bits select the gain for the oscillator. The listed maximum frequencies are recommendations, and might vary
based on capacitive load and crystal characteristics. Setting this bit group has no effect when the Automatic Ampli-
tude Gain Control is active.
These bits select the gain for the oscillator. The listed maximum frequencies are recommendations, and might vary
based on capacitive load and crystal characteristics. Setting this bit group has no effect when the Automatic Ampli-
tude Gain Control is active.
Table 16-8. Oscillator Gain
z
Bit 7 – ONDEMAND: On Demand Control
The On Demand operation mode allows an oscillator to be enabled or disabled, depending on peripheral clock
requests.
The On Demand operation mode allows an oscillator to be enabled or disabled, depending on peripheral clock
requests.
0x6
64
3
1953µs
0x7
128
3
3906µs
0x8
256
3
7813µs
0x9
512
3
15625µs
0xA
1024
3
31250µs
0xB
2048
3
62500µs
0xC
4096
3
125000µs
0xD
8192
3
250000µs
0xE
16384
3
500000µs
0xF
32768
3
1000000µs
GAIN[2:0]
Recommended Max Frequency
0x0
2MHz
0x1
4MHz
0x2
8MHz
0x3
16MHz
0x4
30MHz
0x5-0x7
Reserved
Table 16-7. Start-UpTime for External Multipurpose Crystal Oscillator (Continued)
STARTUP[3:0]
Number of
OSCULP32K Clock
Cycles
OSCULP32K Clock
Cycles
Number of XOSC
Clock Cycles
Clock Cycles
Approximate Equivalent Time
(1)(2)(3)