SAM7L128 Atmel Corporation, SAM7L128 Datasheet - Page 215

• Manufacturer Part Number: SAM7L128
• Manufacturer: Atmel Corporation

Specifications of SAM7L128

• Flash (kbytes): 128 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 36 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 80
• Ext Interrupts: 80
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Segment Lcd: 40
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 4
• Adc Resolution (bits): 10
• Adc Speed (ksps): 460
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 6
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 1.8 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

24.5
24.5.1
6257A–ATARM–20-Feb-08
Main Clock
2 MHz Fast RC Oscillator
Figure 24-3
Figure 24-3. Main Clock Block Diagram
The Main Clock has two sources:
After reset, the 2 MHz Fast RC Oscillator is enabled and selected as MAINCK. MAINCK is the
default clock selected to start up the system.
Startup-up time specifications are provided in the “DC Characteristics” section of the product
datasheet.
The software can disable or enable the 2 MHz Fast RC Oscillator with the MAINCKON bit in the
Clock Generator Main Oscillator Register (CKGR_MOR).
When disabling the Main Clock by clearing the MAINCKON bit in CKGR_MOR, the MAINRDY
bit in the Power Management Controller Status Register (PMC_SR) is automatically cleared,
indicating the Main Clock is off.
Setting the MAINRDY bit in the Power Management Controller Interrupt Enable Register
(PMC_IER) can trigger an interrupt to the processor.
It is recommended to disable the Main Clock as soon as the processor no longer uses it and
runs out of SLCK or PLLCK.
Disabling the MAINCKON bit is also used to go into WAIT mode. The user sets the Main Clock
as Master clock and disables the Main Clock by clearing the MAINCKON bit.
To wake up from WAIT mode, a fast startup must be done. See
• 2 MHz Fast RC Oscillator which starts very quickly and is used at startup
• an external clock (CLKIN)
shows the Main Clock block diagram.
CLKIN
Slow Clock
SLCK
Embedded
2 MHz RC
Oscillator
MAINCKON
AT91SAM7L128/64 Preliminary
Main Clock
MAINCKON
Frequency
MCKSEL
Counter
1
0
MAINCKON
Section 25.6 ”The Fast
Main Clock
MAINCK
MAINRDY
MAINSELS
MAINFRDY
MAINF
Startup”.
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