AT91SAM9G45-EKES Atmel, AT91SAM9G45-EKES Datasheet - Page 294

• Manufacturer Part Number: AT91SAM9G45-EKES
• Description: KIT EVAL FOR AT91SAM9G45
• Manufacturer: Atmel
• Series: AT91SAM Smart ARMr
• Type: MCUr

Specifications of AT91SAM9G45-EKES

• Contents: Board
• Processor To Be Evaluated: SAM9G45
• Data Bus Width: 32 bit
• Interface Type: I2C, SPI, UART
• Maximum Operating Temperature: + 50 C
• Minimum Operating Temperature: - 10 C
• Operating Supply Voltage: 1.8 V to 3.3 V
• For Use With/related Products: AT91SAM9G45
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: Q4626953

24.4
24.5
294
Slow Clock RC Oscillator
Slow Clock Selection
AT91SAM9G45
Figure 24-2. Typical Slow Clock Crystal Oscillator Connection
The user has to take into account the possible drifts of the RC Oscillator. More details are given
in the section “DC Characteristics” of the product datasheet.
The AT91SAM9G45 slow clock can be generated either by an external 32,768 Hz crystal or by
the on-chip RC oscillator. The 32,768 Hz crystal oscillator can be bypassed by setting the bit
OSC32BYP to accept an external slow clock on XIN32.
The internal RC oscillator and the 32,768 Hz oscillator can be enabled by setting to 1, respec-
tively, RCEN bit and OSC32EN bit in the System Controller user interface. The OSCSEL
command selects the slow clock source.
Figure 24-3. Slow Clock Selection
RCEN, OSC32EN,OSCSEL and OSC32BYP bits are located in the Slow Clock Control Register
(SCKCR) located at address 0xFFFFFD50 in the backed up part of the System Controller and so
are preserved while VDDBU is present.
After a VDDBU power on reset, the default configuration is RCEN=1, OSC32EN=0 and OSC-
SEL=0, allowing the system to start on the internal RC oscillator.
The programmer controls the slow clock switching by software and so must take precautions
during the switching phase.
XOUT32
XIN32
XIN32
32,768 Hz
Crystal
Slow Clock
Clock Generator
Oscillator
On Chip
RC OSC
XOUT32
GNDPLL
Slow Clock
SLCK
OSCSEL
OSC32EN
OSC32BYP
RCEN
6438F–ATARM–21-Jun-10